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Neurological Physiotherapy
For Churchill Livingstone:
Editorial Director (Health Professions): Mary Law Project Development Manager: Dinah Thorn Project Manager: Derek Robertson Design Direction: George Ajayi
Edited by
Consultant in Neurological Physiotherapy, London, UK
CHURCHILL LIVINGSTONE An imprint of Harcourt Publishers Limited
© Harcourt Publishers Limited 2002
is a registered trademark of Harcourt Publishers Limited
The right of Susan Edwards to be identified as editor of this work has been asserted by her in accordance with the Copyright, Designs and Patents Act 1988
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without either the prior permission of the publishers (Harcourt Publishers Limited, Robert Stevenson House, 1-3 Baxter's Place, Leith Walk, Edinburgh EH1 3AF), or a licence permitting restricted copying in the United Kingdom issued by the Copyright Licensing Agency, 90 Tottenham Court Road, London W1P OLP.
First edition 1996 Second edition 2002
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging in Publication Data
A catalog record for this book is available from the Library of Congress
Medical knowledge is constantly changing. As new information becomes available, changes in treatment, procedures, equipment and the use of drugs become necessary. The editor, contributors and the publishers have taken care to ensure that the information given in this text is accurate and up to date. However, readers are strongly advised to confirm that the information, especially with regard to drug usage, complies with the latest legislation and standards of practice.
Printed in China
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6. General principles of treatment 121
7. Drug treatment of neurological
Philippa Carter, Susan Edwards
disability 155
Alan J. Thompson
1. Problem solving in neurological
8. Case histories
physiotherapy - setting the scene 3 Margaret J. Mayston
2. Assessment, outcome measurement and goal setting in physiotherapy practice 21 Jennifer A. Freeman
3. An analysis of normal movement as the basis for the development of treatment techniques 35 Susan Edwards
4. Neuropsychological problems and
9. Posture management and special seating 189 Pauline M. Pope
10. Splinting and the use of orthoses in the management of patients with neurological disorders 219 Susan Edwards, Paul T. Charlton
11. Longer-term management for patients with residual or progressive disability 255 Susan Edwards
solutions 69
12. The way forward
Dawn Wendy Langdon
Cecily Partridge
5. Abnormal tone and movement as a result of neurological impairment: considerations for treatment 89 Susan Edwards
Philippa Carter MCSP Superintendent Physiotherapist, King's College Hospital, London, UK
Paul T. Charlton DipOrthotics DipOTC Senior Orthotist specialising in Neurology, J.C. Peacock & Son Ltd, Orthotic Services, Newcastle upon Tyne
Susan Edwards FCSP Consultant in Neurological Physiotherapy, London, UK
Jennifer A. Freeman PhD BAppSc MCSP Research Fellow, Institute of Neurology, London, UK; Lecturer, University of Plymouth, Plymouth, UK
Dawn Wendy Langdon MA MPhil PhD CClinPsychol AFBS Department of Psychology, Royal Holloway, University of London, Egham, UK
Margaret J. Mayston PhD MSc BAppSc MCSP Director, The Bobath Centre for Children with Cerebral Palsy and Adults with Neurological Disability; Lecturer, Department of Physiology, University College London, London, UK
Cecily Partridge PhD BA(Hons) FCSP Reader in Physiotherapy, Centre for Health Services Studies, The University of Kent, Canterbury, UK
Pauline M. Pope MSc BA FCSP Consultant in Disability Therapy, Mary Marlborough Centre, Nuffield Orthopaedic Centre NHS Trust, Oxford, UK
Alan J. Thompson MD FRCP FRCPI Garfield Weston Professor of Clinical Neurology and Neurorehabilitation, Institute of Neurology, London, UK
This book aims to provide both undergraduate and qualified therapists with an improved understanding of problems commonly encoun- tered in their work with people with neurological disability. It is a daunting process, particularly in the light of the ever-increasing availability of knowledge and information related to the control of human movement.
It must be emphasised that the perspective of this book is clinical and arises from clinical experi- ence. This approach to management is based on using the analysis of movement as a means to eval- uate disability resulting from a wide variety of neurological conditions. The need for evidence- based practice is recognised and, wherever possi- ble, references are given to support the text. However, I have not been constrained by lack of publications in making assertions about treatment approaches. There is a continuing challenge to sub- stantiate the constructive and functional changes demonstrated by patients treated in this manner.
There are many people who have provided invaluable support and assistance to me in com- piling this second edition. Jon Marsden, senior physiotherapist at the Human Movement and Balance Unit, Queen's Square, London provided a constant supply of articles and books that enabled me to produce the first edition. For this second edition, in spite of his PhD commitments, he again found time to provide constructive comment and must take full credit for the revised section on ataxia in Chapter 5.
Numerous colleagues have read and critically appraised many of the chapters, for which I am
most grateful. I hesitate to name them all for fear of inadvertently omitting one from such a large number of individuals. My thanks also go to the other authors in this book: Margaret Mayston for 'setting the scene'; Jenny Freeman for her chapter on assessment and outcome measures; Dawn Langdon and Pauline Pope for updating their previous contributions; Alan Thompson for his chapter on drug management; and Cecily Partridge for proposing 'the way forward'.
I would like to acknowledge the therapy staff in the Directorate of Neurorehabilitation and Therapy Services at the National Hospital for their continued support, despite the fact that I no longer work there, and for taking part in the orig- inal, and some of the new, photographic sessions. I also wish to thank George Kaim, head of the Audio-visual Department at the National Hospital who was responsible for many of the original photographs which, some readers may note, are unchanged from the first edition and David Waldman for the new photographs in the splinting section.
And finally my thanks to family and friends who, in spite of questioning my reasoning for embarking on a second edition, have continued to provide invaluable support and appropriate distraction. The regular bridge and sports events have gone some way to preserving some degree of sanity in an otherwise frenzied 2 years of my life.
Susan Edwards
The purpose of this book is to describe aspects of posture and movement and difficulties which may arise as a result of neurological damage. The emphasis is on the analysis of the abnormal pathology which prevails and determining appropriate treatment interventions. The ability to solve problems has been described as an integral part of physiotherapy practice (Newman Henry 1985). 'Problem solving' is a term often used in the management and treatment of patients with a variety of disabilities and particularly for those with neurological dys- function. Patients with neurological disability may present with complex and extensive move- ment disorders in addition to cognitive and sensory impairments. Analysing these deficits and determining the most appropriate course of treatment is the aim of all staff working in this field.
Problem solving may be considered in the context of both the physiotherapist identifying the patient's problems and adopting an appro- priate treatment approach and the patient himself learning to contend with the movement deficit through compensatory strategies. Much has been written with respect to the former, the terms 'clinical reasoning' and 'problem solving' often being used synonymously (Higgs 1992). The concept of the patient being a problem solver is perhaps less well recognised.
The physiotherapist as a problem solver is dependent upon an accurate and extensive knowledge of movement, taking into considera- tion all aspects of the impairment which may contribute to the movement deficit. The patient,
unable to function in the same way as before the onset of his neurological deficit, must determine the most efficient way to contend with his dis- ability. Function is the ultimate goal for both parties but the means by which this is attained raises several issues. The current clinical environment requires that the therapist makes judgements that weigh the advantages and disadvantages of each inter- vention (Shewchuk & Francis 1988). While quality of movement is imperative for optimal function, it
must be recognised that, for the majority of patients with neurological disability, restoration of normal movement is often an unattainable goal. There must be a balance between re-education of more normal movement patterns and acceptance, and indeed promotion, of necessary and desirable compensation. Patients, therefore, must be involved in the decision-making process. 'In essence, they have a PhD in their own uniqueness that is very powerful in solving complex problems' (Weed & Zimny 1989).
Higgs J 1992 Developing clinical reasoning competencies. Physiotherapy 78: 575-581 Newman Henry J 1985 Identifying problems in clinical problem solving. Perceptions and interventions with nonproblem-solving behaviors. Physical Therapy 65(7):
Shewchuk R M, Francis K T 1988 Principles of clinical decision making - an introduction to decision analysis. Physical Therapy 68(3): 357-359 Weed L L, Zimny N J 1989 The problem-orientated system, problem knowledge coupling and clinical decision making. Physical Therapy 69(7): 565-568
Margaret J.
A therapist using a problem-solving approach to the management of neurological patients prior to the 1940s may have asked: How can I train the person to use their unaffected body parts to com- pensate for the affected parts, and how can I prevent deformity? The result was a strong emphasis on orthopaedic intervention with various types of splints, strengthening exercises and surgical intervention. However, in the 1940s several other ideas emerged, the most popular being the Bobath approach. Bobath (1985) with others, such as Peto (Forrai 1999), Kabat & Knott (1954), Voss (1967) and Rood (1954), pioneered the neurological approach to these disorders, recognising that patients with neurological impairment, in particular stroke patients, had potential for functional recovery of their affected body parts. For the child with a neurodevelop- mental disorder, the approach was based on the idea that each child's development could be guided by the therapist, to maximise their poten- tial for functional independence and minimise contractures and deformities. While the Bobath approach is one of the most used and accepted in the UK, little has been written about it in recent years, and there is no robust evidence for its efficacy (Davidson & Waters 2000).
In the last few years there has been a further progression in the neurorehabilitation field, with increasing interest in different models of central nervous system (CNS) function, skill acquisition and training. For example, for some therapists, the emphasis for retraining of the neurologically
impaired person now is on the biomechanical requirements of a task (Carr & Shepherd 1998), accepting that the patient has to compensate for their damaged nervous system. Carr and Shepherd are to be applauded for their well- researched approach; however, it should be recognised that their actual ideas for manage- ment largely arose from the work of Bobath. The emphasis on patient participation and practice is helpful for the cognitively and physically able person, but it is unclear how the approach can be used with people who have significant neurological impairments.
It must be realised that the nervous and mus- culoskeletal systems cannot be separated; they interact with each other to meet the demands of both the internal and external environment. Thus it is important to approach the person with movement disorder with a balanced view of the neural control of movement, the biomechanical requirements for a task and the limitations of CNS damage on both of these systems.
In order to use a problem-solving approach for the treatment of people with neurological dis- ability, it is necessary to have an understanding of the control of movement, the result of damage to different areas of the CNS, neuroplasticity and ways to promote skill learning.
There are many models of motor control. Some examples are neurophysiological, systems/dis- tributed model, neurobehavioural, engineering model, information processing and biomechani- cal. All have value, but individually do not provide the therapist with complete information on which to base their practice. Therefore an understanding of different approaches is help- ful for the therapist working in the neuro- rehabilitation field. The most relevant of these are discussed below.
there is an interaction
between central and peripheral components of
the CNS (see Dietz 1992 for a review). Dietz (1992) points out that neuronal mechanisms are a part of biomechanical strategies but are them- selves constrained by biomechanics. This view is supported by Martenuik et al (1987) who make the following comment: 'While there are biome- chanical factors which constrain movement control processes, there are also brain mechan- isms which are potentially complementary to the biomechanical factors that take part in the plan- ning and control processes. We cannot neglect
one at the expense of the other ...
What then do
we need to know about the neurophysiological
control of movement?
Early ideas suggested that the CNS controlled movement primarily by reacting to sensory input (Foster 1985, Sherrington 1906). Roland et al (1980) demonstrated the presence of brain activ- ity when simply imagining a movement by studying changes in regional cerebral blood flow. This work alongside other studies of CNS activ- ity during function (Deecke et al 1969, Shibasaki & Nagae 1984, Kristeva et al 1994) has demon- strated activity of the brain before a movement begins, and has shown that the nervous system is largely proactive and not simply reactive, in response to sensory feedback. Central (feedfor- ward) mechanisms are based on innate and ongoing experiences of the individual and can take place in the absence of any kind of sensory feedback. Keele (1968) suggested that the CNS organises a general plan in advance of the task to be executed, referred to as the motor programme, on the basis of prior experience. Schmidt (1991) has taken up this idea of programme-based motor control, describing the comparative nature of how the brain organises the preparation and execution of movements. Much debate has taken place about the role of the motor programme and sensory feedback from the periphery in motor control (Morris et al 1994). However, it is clear that both central and peripheral factors are important in the efficient execution of motor tasks.
Central programming requires the integration of many neural structures, both supraspinal and in the periphery, to produce the required output to achieve the task goal. It is helpful to consider
Figure 1.1
Knowledge of how different parts of the CNS
connected to each other can be helpful in understanding the control of movement. (From Kandel et al 1991, p. 539.)
the wiring-type diagram which gives an idea of how different parts of the CNS interact (Fig. 1.1), but this gives little insight into the contribution of different systems to the control of movement. The advent of imaging techniques such as positron emission tomography (PET) and func- tional magnetic resonance imaging (fMRI) have enabled a window into the CNS to provide greater insight into how tasks are organised. For example, a recent PET study by Jueptner & Weiller (1998) shows that the cerebellum is mostly concerned with processing of sensory information during an ongoing task whereas the basal ganglia are more concerned with organisa- tion of well-learned tasks. Neurophysiologists suggest that the CNS organises the required neural activity to perform a task on the basis of past experience, but, if prior knowledge is lacking, feedback systems will play a greater role. These of necessity take longer to effect a response. Information needs to be transmitted from the periphery to supraspinal structures for processing and the result sent via efferent path- ways to the spinal cord and muscles acted on.
Feedback systems are therefore less efficient and inadequate to effect fast action. For example, take the task of drinking from a cup. There are several stages in this process. First, there needs to be a stimulus generated, either internally or externally; for example, thirst or a social situation. On the basis of past experience, the CNS organises the required strategy to achieve the goal. Perceptual aspects such as the weight, shape and texture of the cup are essential in order for the correct grip and load forces to be computed by the CNS. Spatial concepts are important for the grading and timing of postural adjustments and the actual limb movements required to take the cup to the mouth. Oral and swallowing musculature need to be coordinated with breathing in order to have the drink without choking. A decision also needs to be made when sufficient liquid has been ingested.
Although sensory information is not necessary for tasks to occur, it is important for the fine- tuning and learning of any motor/postural task. Studies on the 'deafferented man' (neuropathy of the large-diameter pathways), have shown that tasks previously experienced by the individual can be performed in the same way, but the need for repetition results in a deterioration in the per- formance of the task, and an inability to learn new skills (Rothwell et al 1982). This is clearly demonstrated by the inability of the 'deaffer- ented man' to drive a new car because the gears were organised differently from the car he had driven previously (Rothwell, personal communi- cation). This highlights the importance of the perception and processing of sensory informa- tion not only for learning but also for the efficient execution of a required task. This is important when considering training neurologically impaired patients who may have difficulties of sensory perception or sensory processing.
It seems that the CNS operates in a task- or goal-directed way, an idea embraced by thera- pists using a motor learning approach (Carr & Shepherd 1998). Studies using transcranial mag- netic stimulation (TMS) have shown that a muscle can be activated the same amount in two tasks, e.g. power and pincer grip, but that the task is organised in a different way by the cortex;
i.e. depending on the complexity of the task, or the prior experience of the task, the CNS will select only the necessary information for its exe- cution (Datta et al 1989, Flament et al 1993, Harrison et al 1994). These experiments have shown that the cortex plays a lesser role in simple well-practised movements such as power grip.
Cross-correlation analysis is a useful technique to study the interactions between muscles and to learn more of the neural organisation of their activity. This computer-driven analysis pro- gramme analyses the times of occurrence of motor-unit spikes and determines the probability of two motoneurones firing at or around the same time more than expected by chance alone. This technique developed by Moore et al (1970) in their study of the simple CNS of the slug (aplysia), has been successfully applied to the study of respiratory muscles and the control of human muscle activity (Sears & Stagg 1976, Bremner et al 1991, Mayston et al 1997, Farmer et al 1998). Figure 1.2 indicates the three possible
probability histograms that can be computed. The histogram in Figure 1.2a has a short duration peak around time zero, indicating that the motoneurone pools which innervate this muscle pair receive shared synaptic input either due to branched synaptic inputs or from branched common presynaptic inputs. Figure 1.2c shows a flat histogram. From this it can be inferred that the probability of firing of motoneurone A & B is always the same and if the two motoneurones do fire simultaneously such activity occurs purely by chance alone. Figure 1.2b shows a histogram with a short duration central trough, indicating shared synaptic inputs which in this case are reciprocal, i.e. excitatory to one and inhibitory to the other. In this way the reciprocal innervation circuit described by Sherrington (1906) can easily be demonstrated using simple surface electro- myographic (EMG) recordings and the appro- priate computer-generated software. Using this simple technique applied to surface EMG record- ings, changes in motor-unit synchronisation fol-
Figure 1.2
Cross-correlation analysis provides a way of examining the synaptic inputs to motoneurone pools which inner-
vate muscle pairs.
lowing stroke have been demonstrated (Farmer et al 1993, Nadler et al 1999a). Similarly, a lack of reciprocal inhibition between antagonistic muscle pairs in healthy children younger than 5 years of age has been demonstrated and found to persist in children with spastic cerebral palsy (Mayston et al 1996, Gibbs et al 1999). Early ideas underlying the Bobath concept emphasised the importance of reciprocal inner- vation circuits in the control of antagonistic muscle pairs and thus smooth coordination of movement (Bobath 1990). Bobath (1990) sug- gested that one of the problems for the patient with increased tone was excessive co-contraction which resulted in stiffness and slow, difficult movements for function. However, reports of abnormal co-contraction in adults with spasticity provide conflicting evidence for the presence of such co-contraction following stroke with muscle changes seemingly the primary problem in the inability to produce adequate force in the agonist, rather than antagonist restraint (Bourbonnais & Van den Noven 1989, Davies et al 1996). In contrast, for children with hypertonic
cerebral palsy, abnormal co-contraction is more common and is likely to contribute to the limb stiffness and associated difficulties in performing postural and voluntary tasks (Berger et al 1982, Leonard et al 1988, Woollacott & Burtner 1996). It is thought that for ataxia pure reciprocal inhibi- tion without the usual overlap period of co- contraction at the reversal of movement direction results in jerky uncoordinated movement (Bobath (1997) course notes).
It is important to understand reciprocal inner- vation in order to appreciate how a disturbance of this mechanism may contribute to the move- ment problems encountered by the neurologi- cally impaired client. Reciprocal inhibition is brought about by the reciprocal innervation circuit described by Sherrington (1906). This is shown in the simple diagrammatic representa- tion in Figure 1.3a (Mayston 1996). It is important to note that the inhibitory interneurone which produces the inhibition of activity in the antag- onistic muscle is facilitated by descending tracts, in particular the corticospinal tract. The efficiency of this reciprocal inhibition circuit
Figure 1.3
The Ia inhibitory interneurone receives input from spinal and supraspinal sources: muscle afferent (spinal) and
the corticospinal tract (supraspinal).
increases with maturation of the nervous system and can be altered as a result of a cortical lesion. Reciprocal inhibition allows for the reciprocal activity of agonist and antagonist as required. For example, biceps activity is required to bend the elbow, usually occurring with the triceps relaxed (i.e. reciprocal "inhibition). However, in order to produce smooth changes in the direction of the movement, the triceps co-contracts for a short time and then becomes the prime mover and the biceps is reciprocally inhibited. To explain the interaction between the agonist and antagonist when both are actively contracting, Sherrington introduced the term double recipro- cal innervation, to explain how the circuits from each muscle will act simultaneously (Sherrington 1906). This is probably why Bobath (1990) emphasised the need for the healthy individual to have all degrees of reciprocal innervation in order to have well coordinated muscle activity for function. In retrospect, it is clear that Bobath placed too much emphasis on abnormalities of co-contraction in his explanation of adult neuro- logical dysfunction, although it seems to be sig- nificant in children with spastic cerebral palsy. This is most likely because these children retain characteristics of the immature CNS, including co-contraction of the limb muscles (Forssberg 1985, Woollacott & Burtner 1996).
In summary, the neurophysiological model helps us to understand the interactions between various neural mechanisms, both central and peripheral, and indicates in particular the impor- tance of supraspinal mechanisms for the modu- lation of spinal systems to produce the required control of movement.
Systems/distributed model
A therapist using a systems-based model on which to base therapy intervention helps the neurologically impaired person to problem-solve the achievement of a task goal, rather than to learn movement patterns (Shumway-Cook & Woollacott 1995). The systems approach has its origin in the work of Bernstein (1967), who sug- gested that an understanding of the characteris- tics of the system being moved (in this case the
human body), and the internal and external forces acting on it, were necessary in order to understand the neural control of movement. He suggested that the control of movements was most likely distributed throughout several coop- erative and interactive systems. This has been described as the distributed model of motor control. Bernstein suggested that we have many degrees of freedom: that is, we have many joints which make several types of movement such as flexion, extension and rotation. In order for co- ordinated movement to occur, muscles are activ- ated together in synergies such as locomotor, postural and respiratory synergies.
To use this approach as a basis for therapy, several assumptions are made (Horak 1992). The major assumption is that movements are organ- ised around a functional goal and achieved by the interaction of multiple systems such as the sensorimotor and the musculoskeletal systems. In addition, this organisation is also determined by environmental aspects, and emphasises the importance of the interaction between the indi- vidual and the environment. The model further hypothesises that the role of sensation is import- ant not only for adaptive control of movement but also to the predictive control of movement. Accordingly, for the neurologically impaired person, abnormal motor control results from impairments in one or more of the systems con- trolling movement and their resultant attempts at achieving functional goals are produced by activ- ity of the remaining systems, which are doing the best they can. It is the therapist's task to improve the efficiency of the person's compensatory strategies to effectively perform functional tasks. While this model may be useful, some difficulty is encountered when the contribution of each system needs to be identified and evaluated.
Engineering model
This is well described by Miall (1995), who explains that the motor system has to solve prob- lems in response to changing sensory inputs, internal goals or errors in performance. He sug- gests that the motor system needs to select an appropriate action, transform control signals
from sensory to motor frameworks, coordinate the selected movement with other ongoing behaviours and postural activity, and then monitor the move- ment to ensure its accuracy and efficacy. In this model, the motor command is sent out to the controlled object (Fig. 1.4). In this example, the arm is the controlled object and the intended position of the arm is the reference. If the con- troller bases its actions on signals which are not affected by plant output (that is the sensory con- sequences of the action) it is said to be a feedfor- ward controller; however, if comparisons are required - for example, between a reference signal or changing signal due to interactions with the environment - then it is a feedback controller.
This is useful for understanding how the nervous system can be both proactive and reac- tive, as already described in the neurophysiolog- ical model: proactive to produce activity on the basis of past performance and knowledge of out- come; and reactive to ensure that the task is executed as required in the context of the chang- ing internal and external environments. How- ever, there is usually a need for error correction before the command is executed and during the task performance. As Miall (1995) suggests, there are many examples of feedback control in physi-
ology, such as changes in muscle length which are detected by muscle spindles relayed to both spinal and supraspinal neural structures. Motor systems also use this information in a feedforward way. For example, the motor com- mand is sent to both alpha and gamma systems to ensure co-contraction of the extrafusal and intra- fusal muscle fibres to enable the sensitivity of the muscle spindle to respond to unexpected load. It must be recognised that feedback systems, although necessary for skill learning and up- dating of motor performance, are slow. It takes a minimum of approximately 50-100 ms for sensory information to be processed by the CNS, which for efficient postural adjustment and fine motor control is a long time. While this is a useful model, because it assumes that the CNS acts in a linear way, there are some limitations when it is applied to brain lesions or neurophysiological recordings (Miall 1995, Loeb et al 1999).
Biomechanical model
It is possible that an overemphasis on the neural
control of movement has led
to a neglect of the
importance of muscle strength, force production
Figure 1.4
Feedforward control in the ideal situation can give perfect performance: i.e. there is no error between the
reference signal and the output of the system (upper panel). A feedback system can correct performance by comparing the
expected and actual outcome of a movement strategy. (Adapted from Miall 1995.)
and movement velocity. Carr & Shepherd (1998) primarily base their therapy of neurological move- ment disorder on principles of motor learning and biomechanics, stressing the importance of muscle length, muscle strength and activation of appropri- ate muscle synergies in a task-specific context. There is good evidence to support this view. Davies et al (1996) showed that a lack of force generation by paretic agonists was the major cause of reduced torque generation in a group of ambu- lant stroke patients. Biomechanical properties of muscle are also an important aspect of force pro- duction and changes in the distribution of muscle fibre types may also contribute to problems of force generation (Edstrom 1970, Dietz et al 1986, Ito et al 1996). It is well known that a muscle will produce optimal force at mid-range where maximal overlap of cross-bridges can occur (Roth- well 1994). Most people with neurological move- ment disorder demonstrate changes in muscle length which no doubt affects their ability to produce adequate force to achieve an efficient movement strategy. These changes in muscle length also alter joint alignment, which affects the ability to generate sufficient torque and efficient muscle activation patterns. It is possible that the inappropriate co-contraction of agonist and antag- onist muscles results from altered biomechanical alignment in addition to abnormal neural control of the reciprocal inhibitory circuits between the muscle pair (Woollacott & Burtner 1996). Neuro- physiotherapists must therefore consider bio- mechanical principles in the assessment and management of the neurologically impaired individual.
Hierarchical model
Although this model is considered outdated, it has some value when one considers the effect of the cortex on the control of movement (Lemon 1993). While it is not thought to be useful to think of higher centres controlling lower centres, the cortex is known to exert considerable control over the spinal cord and acts with subcortical areas such as the cerebellum and basal ganglia in the selection, planning and execution of motor commands (Shibasaki et al 1993, Winstein et al 1997). The
cortex though traditionally associated with the control of skilled voluntary movements, has been shown to be active during more automatic activi- ties such as swallowing (Hamdy et al 1998) and locomotion (Schubert et al 1997, Capaday et al 1999). Another departure from the traditional view of motor control is that the spinal cord is capable of producing motor activity without any input from supraspinal centres, just as the cortex can generate commands without feedback from the periphery. This has been well described in the work on central pattern generators (Grillner 1985, Rossignol et al 1988). The central pattern generator is defined as a
'network of neurones tive, rhythmic output
able to produce a repeti- that is independent of
... necessary sensory feedback' (Delcomyn 1980). In this way, the spinal cord via its networks of interneurones and motoneurones, can produce rhythmical, alternating lower limb movements which are the basis of locomotor activity (walking). On the other hand, fractionated finger movements necessary for fine hand control rely on the integrity of the corticospinal tract for their efficiency and are largely under cortical control (Lemon 1993, Olivier et al 1997). It is well known that a lesion affecting the corticospinal tract results in deficits of inde- pendent finger movements (Kuypers 1978, Galea & Darian-Smith 1997, Farmer et al 1993).
The view that the cortex has an important influence on control of the spinal cord's organ- isation of movement is also reflected in reflex studies. Matthews (1991) presents a comprehen- sive review of the human stretch reflex which consists of a short latency component (M1) and a long latency component (M2). This paper reviews the evidence from studies of latencies of reflex components, lesions and stimulation techniques which show that the simple stretch reflex is more complex than originally proposed by Liddell & Sherrington (1924, as cited in Matthews 1991). Matthews (1991) presents robust evidence for a transcortical route for the transmission of the long latency M2 component.
Successful performance of a sensorimotor task requires the integrated action of the CNS.
Descending commands from the brain interact with spinal neuronal circuits, and incorporate the dynamic properties of muscles and activity of somatosensory receptors (Loeb et al 1999). From the previous discussion it can be concluded that no one model is sufficient for the therapist to apply a problem-solving approach to the man- agement of the neurologically impaired person. The musculoskeletal system is critical to the exe- cution of the motor command, in addition to the various cortical and subcortical areas involved in the organisation of the task. Therapists must understand the nature of the movement disorder to employ effective treatment strategies and to set appropriate goals for those individuals to maximise the potential for functional independ- ence.
Which therapy approach?
It is thought that approximately 88% of thera- pists in the UK base their intervention on the Bobath concept (Sackley & Lincoln 1996, Davidson & Waters 2000). Although there have been changes to the underlying basis of the concept (Mayston 1992), the lack of relevant liter- ature has resulted in many misconceptions and continuation of outdated ideas, such as an emphasis on reflex activity as a basis of tone and postural activity, a correspondingly misplaced emphasis on the inhibition of spasticity and an overemphasis on the significance of righting and equilibrium reactions. The following discussion attempts to clarify some of the basic ideas under- lying the Bobath approach to the management of people with neurological movement disorder.
Normal and abnormal tone
It is clear from the neurophysiological and bio- mechanical models of motor control that the muscles themselves are important contributors to the concept of tone. The original idea proposed by Sherrington (1906) and adopted by Bobath (1990) that tone is the result of tonic reflex activ- ity is now outdated. Tone comprises both neural and non-neural components (Basmajan et al 1985). Various definitions lead the therapist to
realise that this is the case. Basmajan et al (1985) states 'at rest a muscle has not lost its tone although there is no electrical activity in it'. Ghez (1991) describes tone as 'a slight constant tension of healthy muscles'. The definition by Bernstein (1967) that describes tone as a state of readiness seems a useful explanation. Different individuals can have differing states of readiness, as do patients with movement disorder: for example, the person with hypotonia has a reduced state of readiness, whereas the person with spasticity/ hypertonia may be said to have an increased state of readiness. If tone is an important aspect of the control of movement, all factors contribut- ing to it must be taken into account. Tone is not simply produced by tonic reflex activity - vis- coelastic properties of muscle are equally impor- tant. This has significance for the movement problems of the patient with abnormal tone. It is now known that muscles which are thought to be hypertonic are in fact not usually overactive but cannot generate sufficient electrical activity to exert a force about a joint or to produce a movement (Davies et al 1996).
The controversy regarding the use of the terms 'spasticity' and 'hypertonia' is discussed in Chapter 5, but the therapist must ask this ques- tion: Am I managing spasticity, hypertonia or both?
An example of clinical practice may help to clarify the dilemma. Recently a 12-year-old child was referred for physiotherapy because of increasing 'spasticity' for which baclofen (an antispastic agent; see Chapter 7) had not been helpful. This girl presented with increasing stiff- ness shown by an increased flexion posture of the lower limbs and resistance to extension. Is the increased stiffness due to:
muscles and associated changes in viscoelastic muscle properties which has resulted in con- tractures and apparently increased tone over time, or • is the increased stiffness due to a velocity- dependent increase in hyperreflexia?
After assessment it was clear that the major factor causing increased stiffness was muscle
weakness and contracture. Therefore it was not surprising that baclofen had no effect in this case. Careful assessment of what is true spasticity as opposed to weakness, loss of dexterity and con- tracture (stiffness) is thus essential and may require specific testing, for example using EMG recordings, in order to be accurately determined.
Are inhibitory techniques relevant?
This altered view of tone must influence the way the therapist manages the person with abnor- mally increased tone. The EMG traces in Figure 1.5a show the activity recorded from the quadri- ceps and hamstrings of a 10-year-old child during free standing, only possible with some flexion of the hips and knees. When the child is aligned so that the hips and knees are extended, the hamstrings are no longer active and the quadriceps generate larger spike EMG, thus acti- vating larger motor units which results in more dynamic postural activity (Fig. 1.5b). Has this child's hypertonia been 'inhibited', or rather does he now have more appropriate alignment to allow more efficient activation of the quadriceps muscle and hip extensors?
The word 'inhibition' poses many problems. Tone may be influenced (reduced) by elongating and mobilising stiff, tight joints and muscles to enable optimal activation from the required
muscles, but this is not inhibition as understood by physiologists. Inhibition in neurophysiologi- cal terms means that synapses are weakened due to reduced transmitter release or that activity in a synapse is dampened down. There are many examples of inhibition in the CNS: for example reciprocal la inhibition, lateral inhibition, Renshaw cell inhibition, pre- and post-synaptic inhibition. The term 'inhibition' was introduced by Bobath to explain tone reduction commensu- rate with the idea that hypertonia was produced by abnormal tonic reflex activity (Bobath 1990). This view can no longer be supported. Bobath therapists achieve tone reduction in various ways: mobilisation of tight joints and muscles, muscle stretch, practice of more normal move- ments (whole or part practice) and functional tasks.
The changes in explanations of tone and tech- niques of handling as viewed by paediatric Bobath therapists are summarised in Table 1.1 which shows how the understanding of abnor- mally increased tone has changed over several decades. Accordingly, the explanation underly- ing the treatment technique has also changed. It has been suggested that therapists do not so much need to change what they do, but to rethink the explanations for what they do (Gentile, personal communication). Another mis- leading term related to 'inhibition' is the tech-
Figure 1.5
The electromyographic (EMG) activity recorded from a 10-year-old child with spastic diplegia standing without
support in a typically flexed posture (a) and when held with the hips and knees extended (b). TIP = tone influencing pattern.
nique of specific inhibitory mobilisations (SIMs) introduced by adult Bobath therapists. SIMs apparently stretch tight ligaments and tendons, and are therefore not inhibitory in the physiolog- ical sense. The activity of every motoneurone pool depends on the sum of the inhibitory and excitatory inputs at any moment in time. It is by altering sensory feedback due to altered task per- formance that the CNS, if it has the capacity to adapt, will then provide the neurologically impaired person with the possibility to move more efficiently or to regain lost skills. This neural approach to client management needs to be integrated with a biomechanical approach which takes into account the importance of muscle length, strength and joint alignment.
Postural control
The early work of the Bobaths placed a great emphasis on postural reactions, namely the right- ing, equilibrium and protective reactions (Bobath & Bobath 1964,1975). They proposed that postural adjustment took place before, during and after an action, an idea shown by researchers in the pos- tural control field (Massion 1994, Gatev et al 1999).
Unfortunately some users of the Bobath approach are still dominated by an overemphasis on these reactions, and even these are not always clearly understood. Bobath therapy is not facilitation of balance reactions, although this is the perception of some workers (Palmer et al 1988). It is perhaps important to review these reactions before a broader discussion of balance. The righting reac- tions are a discrete group of reactions which are only seen in the developing infant and in specific animal preparations. In the mature adult these righting reactions cannot be separated from the more complex equilibrium reactions (Bryce 1972). It is therefore incorrect to look for head righting or trunk righting in the mature adult, but rather one should determine whether an individual has the appropriate activity of the head and trunk within the equilibrium response. The equilibrium reac- tions are either:
• invisible changes in muscle tone which enable the maintenance of the desired posture, • or, when greater perturbation necessitates visible activity, the response of the body being to extend/elongate the weight-bearing side with flexion of the non-weight-bearing side with some rotation within the body axis. The degree of rotation depends on the direction of the perturbation. When the perturbation is too large or too fast then the protective reactions come in to protect the individual from injury and to assist in restoration of the centre of gravity to lie within the base of support.
In summary, balance in the mature adult is achieved by equilibrium and protective reac- tions; righting reactions cannot be observed. In the developing infant the various righting reac- tions can be observed, but early in development become a part of the equilibrium reactions which commence in prone at approximately 3 months of age when the infant can maintain the prone position with head lifting and weight on elbows.
For several years, balance has been viewed in a functional way by the Bobath Centre, London, recognising that the central command for an action includes both the postural and task- related components (Rothwell 1994). Balance reactions are complex responses based on prior
experience in addition to the CNS response to unexpected perturbations occurring during task execution (Horak & Nashner 1986). There seems to be much controversy about how balance should be trained in people with neurological movement disorder. Should balance be trained separately or as part of the task goal? For the developing infant the experience of a posture precedes the attainment of postural control in that posture. For example, an infant is propped in sitting to practise using their hands before inde- pendent sitting is possible. Thus, for some patients, it could be reasonable to assume that it is necessary to give them the idea of the postural activity required for a task and then to add in the task component. Both components need to be practised simultaneously for the training to be effective. Similarly, testing of sitting balance is not achieved by testing righting and equilibrium reactions, but rather by assessing the person's possibilities to reach in all directions for objects or to carry out activities as in the performance of tasks of daily life. This ability relies not only on sensorimotor activity but also on the perceptual ability of the individual (Massion 1994), which should be considered as part of the postural mechanism to be taken into account during therapy and the goals adjusted accordingly. If a person's instability is primarily caused by a per- ceptual deficit, simply training balance reactions will not address the main problem.
It would be preferable to view balance as an adaptable background to skill performance and to train it in the appropriate functional context, rather than emphasising the different groups of reactions (righting, equilibrium and protective) as being responsible for postural control.
How the patient moves in response to their neu- rological reorganisation is another question. Shepherd & Carr (1991) suggest that the way in which the neurologically impaired person attempts to achieve a goal represents the best that can be done given the state of the neural and musculoskeletal systems. The questions we might ask are: How much does the person need to compensate? Can they function more effi- ciently and compensate less? For example, a stroke patient will prefer to use the unaffected side, only using the stroke-affected side when absolutely necessary and only if physically possi- ble. However, the work of Bobath (1990) and evi- dence provided by Taub & Wolf (1997) has shown that by training of the stroke-affected side it is possible that, for some patients, fewer com- pensatory movements will be required because more effective movement is possible on the stroke side. No therapist should try and stop a patient moving in a certain way unless they can replace it with an alternative strategy which achieves the same goal. Concern for quality of movement needs to be realistic.
Associated reactions
Associated reactions (see Chapter 5) are another example of confusion in neurophysiotherapy and represent one of the greatest controversies and possibly mysteries in the neurological therapeu- tic world in the UK (Stephenson et al 1998). Early positioning and the avoidance of effort were advocated by Bobath (1990) to reduce the effect of associated reactions which in the long- term might lead to contracture and reduce the potential for functional recovery. The main fea- tures of the management of these reactions in the more able client were:
Compensation is another term which has differ-
ent meaning for therapists, neurologists and movement scientists. If the nervous system is damaged in some way, then there will necessar-
reduce them when they occurred. For exam- ple, using the sound arm to stretch out the affected side.
ily be compensation by the system for the damage sustained. This can take many forms, which may include plastic changes such as muscle adaptation and cortical reorganisation.
To train more normal activity of the affected side to reduce effort and therefore the severity of the associated reactions. It was suggested that improving balance on the stroke-affected
side could lead
tenance of balance and less increase of tone in
the upper limb associated with the need balance.
However, there is no evidence to suggest that preventing a person who has had a stroke from moving in the early stages of recovery will influ- ence spasticity and associated reactions; in fact, it may be detrimental to the client's potential for CNS recovery and thus functional recovery.
co-contraction of antagonistic muscle pairs (Leonard et al 1991, Woollacott & Burtner 1996, Gibbs et al 1999). There are varying reports of co- contraction of antagonistic muscle pairs in adults with hypertonia, but the phenomenon seems less common. It is likely that weakness and altered viscoelastic properties of muscle are a more likely explanation of the stiffness experienced and felt in adult patients with increased tone (Gowland et al 1992, Davies et al 1996).
It would seem that therapists have become so enthusiastic in the control of tone that other factors, such as weakness and dexterity, have assumed less importance. But a purely biome- chanical view cannot be supported either. Neural damage that results in dysfunction of cortical and subcortical areas, particularly the descend- ing tracts, reduces neural drive onto the motoneurone pool and results in reduced force generation which will not necessarily be regained. Thus there will always be a degree of weakness and loss of power. Muscle imbalance will be accompanied by muscle shortening, another contributor to lost ability to generate force - for example in walking (Ada et al 1998).
It has been shown in children with cerebral palsy (CP) that the inability selectively to activate muscles is in part due to a lack of synchronisa- tion of muscles (Gibbs et al 1999). Axons usually branch to innervate several motoneurone pools to bring about the cooperative action of the muscles for a required task (Bremner et al 1991), or are activated synchronously if flexible strate- gies are required by the task (Gibbs et al 1995). This is one aspect of function of the corticospinal tract known to be disrupted when there is brain injury. Abnormal synchronisation of motor unit activity has been demonstrated in people with dystonia (Farmer et al 1998) and those with hemiplegic stroke (Farmer et al 1993, Nadler et al 1999), although the functional significance of this is unclear Another aspect of the movement disorder associated with spasticity in children is
THE WAY FORWARD Neuroplasticity
Plasticity underlies all skill learning and is a part of CNS function in healthy and brain-damaged individuals at any age (Leonard 1998). The advent of imaging techniques such as PET and fMRI in conjunction with neurophysiological recordings in primates and humans has provided evidence of the plasticity of the CNS. In a study of monkeys following amputation of digit 3, it was shown that adjacent areas of the sensory cortex expanded to take over the representation of the lost digit (Merzenich et al 1984). Plasticity of the sensory cortex has also been induced through behavioural training. The tips of the second and third fingers were stimulated with a rotating disk, which resulted in an expansion of the sensory representation of those digits (Jenkins et al 1990). This suggests that sensory stimulation, if given effectively and often enough, can expand sensory areas of the cortex and may have implications for therapy.
Plastic changes have also been demonstrated in the motor system as a result of motor training. Recent work by Nudo and his group (Nudo et al 1992) has shown that training a hand expanded the cortical areas represented by the muscles executing that task. A later study by his group has shown that lesioning the motor cortex of a monkey and then training motor activity during recovery resulted in greater recovery of skill than the untrained group, and reduced loss of cortical tissue in the area surrounding the infarct (Nudo et al 1996). The effect of training of a novel motor skill in healthy human adults has also
demonstrated changes in sensorimotor function (Nadler et al 1998). In this study subjects were trained to simultaneously flex the index finger (first dorsal interosseous; 1DI) and abduct the fifth finger (abductor digiti minimi; ADM). Before, during and after the training period, cuta- neomuscular reflexes in response to stimulation of the digital nerves of the index finger were recorded. After a short period of training (2-3 days), the long-latency components of the reflex were significantly larger. This indicates that the sensory fields of the two muscles had expanded and come to lie closer together in the sensory cortex, so that the sensory input now reached the two muscles rather than just the 1DI. This corre- late of Nudo's work in training motor skill in monkeys (Nudo et al 1992) suggests that motor training and skill learning can be detected using simple reflex testing and may be useful as a means of monitoring the effects of therapy in clients with neurological disability.
patient wants to achieve. To do this requires
realistic goal setting.
Bobath (personal communication) suggested that it is what the neurologically impaired person can do with some assistance that is their potential. However, it is of little use to the person if these potentially achievable skills can only be practised with the therapist's help. When required, it is appropriate and important to enlist the help of others to enable the person to practise activities which are possible, with a little help, to achieve independently. Equally it is of no use to the person to be prevented from trying to practise activities because there is a danger of increasing spasticity through the occurrence of associated reactions. Indications are that early training will enable less secondary loss of cortical tissue and thus enable greater possibilities for recovery (Nudo et al 1996).
Skill learning
Practice is fundamental for motor learning and improving skill in both healthy and movement- impaired individuals (Taub et al 1993, Winstein et al 1997). Two other principles of equal signifi- cance are active participation and working to achieve meaningful goals. Therapy programmes should be based on these three principles and can be enhanced by 'preparation'.
The Bobath approach has been much criticised for its use of preparation for function (Shepherd 1995, Carr & Shepherd 1998), but this has been misunderstood. Preparation given as a treatment is of no value on its own, and must be incorpo- rated into useful activity (Bobath 1965, unpub- lished notes). It includes the following:
• mobilisation of tight connective tissue and/or joints • elongating muscles to enable activity from a better biomechanical advantage, to achieve better body alignment for more efficient balance and muscle activation practice of task-component parts to enable the patient to get the idea of the movement required
Can we predict outcomes?
Part of the realistic setting of goals (see Chapter 2) depends on having realistic expectations of the individual's optimal potential based on the ther- apist's expertise. However, neurophysiological tests such as TMS and reflex testing may also be used to predict recovery. Turton et al (1996) in their study were able to identify two patient groups (A = rapid recovery; B = slow and incom- plete recovery) and further categorised them on the basis of EMG recordings and responses to TMS. While responses to TMS could be elicited from all muscles in group A from the outset, in the slow recovery group, the ability to elicit TMS responses was commensurate with the subse- quent activation of hand muscles. In this way TMS provided a prognostic test for the return of muscle activity.
Nadler et al (1999b) studied the cutaneomus- cular reflexes (see Jenner & Stephens 1982) of a small cohort of people who had a stroke. Their results suggest that those subjects in whom a large short-latency reflex response is recorded are unlikely to make a good recovery. Similarly, stroke patients who present with transient mirror
movements early in recovery usually regain good function of that side (clinical observation). However, not all therapy departments have access to these diagnostic and prognostic tools; therefore, for the moment, the clinical experience
and the problem-solving ability of the therapist in the context of a knowledge and understanding of current research literature remains the main way to determine realistic goals for each client's management.
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Introduction 21
Key elements of the assessment process
The importance of reassessment
Measuring outcome
A framework for measurement 26 General principles of outcome measurement 26 Available measures 29
Goal setting
General principles of goal setting
Jennifer A.
In the past decade there has been an increasing demand on all health care professionals to provide evidence to support the effectiveness of their interventions and 'to make conscientious, explicit and judicious use of current best evi- dence to make decisions about the care of indi- vidual patients' (Sackett et al 1996). This concept of evidence-based practice is now widely con- sidered to be best practice. Comprehensive assessment and outcome measurement are inte- gral to this process. There are two main aims of this chapter. The first is to describe the general principles of assessment, outcome measurement and goal setting. The second is to stress the importance of incorporating these principles in daily clinical practice. This chapter provides some guidelines on how to achieve this. For this purpose the chapter has been divided into three distinct sec- tions. In reality, however, the three concepts are closely interrelated.
Assessment is considered to be the first step in the process of rehabilitation (Wade 1998a). It is a continuous process by which information is gathered from a variety of sources, and then interpreted with the aim of identifying key prob- lems and formulating a treatment plan relevant to the needs of the individual. In neurological physiotherapy its primary purpose is to describe the patient, and to objectively record and com-
municate findings about patients' movement dis- orders and activity levels (Bowers & Ashburn
Johnson & Thompson (1996) emphasise the importance of good quality assessment by stating that the 'quality of care given can only be as good as the assessment on which it is based. Effective physiotherapy management of disordered move- ment and function is therefore reliant upon accu- rate measurement and analysis of movement, posture and function (refer to Chapter 3). In neu- rological conditions, where the problems are often multiple, complex and interrelated, this not only requires considerable knowledge and skill about movement but also a willingness to consider a wide range of additional factors which may con- tribute to the problem. It requires the ability of therapists to recognise their own areas of expertise and limitations, and to refer to other professionals when indicated. There are many examples within clinical practice where an initial assessment may trigger referral to another professional to seek essential additional information to inform the planning of intervention. For example, referring for assessment of vision or blood pressure in the case of a person who is repeatedly falling but who has no apparent difficulties with movement; or to a psychologist when low mood appears to be impacting upon the patient's ability to participate in treatment. Just as we may depend upon other people for information, so too may our findings be beneficial in guiding the intervention of others. For example information about the ability of a patient to maintain a sitting posture will guide wheelchair and seating provision; assessment of tone and its response to pharmacological interventions (such as botulinum toxin or intrathecal baclofen) will guide optimal drug dosage. These examples high- light the necessity for collaborative multidiscipli- nary team working, an approach which is now widely considered fundamental to optimal patient management (Wood 1993).
While there is little evidence to guide one on the most appropriate or efficient methods of assess-
ment (Wade 1998a), there appears to be general agreement with regard to the essential steps in the assessment process. These are outlined in the following sections.
Background information from other relevant sources such as medical notes, investigations and psychology assessments informs the initial assessment process and minimises duplication of questioning and assessment.
clinical interview
Interviewing the patient is an important aspect of the physiotherapy assessment. Table 2.1 provides a brief overview of important data to collect during the interview. It is not usually feasible to gather all of this information at a single session, and hence this process will be ongoing through- out treatment. Froelich & Bishop (1977) consider that there are a number of aims of the interview:
to establish a relationship with the patient; gather information about their needs; and help them to understand their condition and the movement difficulties that arise from it. Croft (1980) believes that the ability of the therapist to create an open and communicative atmosphere, whereby infor- mation can be readily offered and received, is fundamental to achieving this aim.
The purpose of the clinical examination is to gain information about the patient's movement disor- der and functional status by observation and examination. An essential prerequisite for this is the ability of the therapist to analyse movement based on a knowledge of normal movement (refer to Chapter 3). Information collected by observation may be subjective and therefore open to error and bias since the descriptions and interpretations can differ widely according to the experience and expectations of the assessor and those who read the records (Bowers & Ashburn 1998). Such information can be made more reli- able if it is structured, in some way, by techniques
such as the use of checklists (for an example see Table 2.1), or standardised and objective assess- ment scales (such as the Motor Assessment Scale, Carr et al 1985). Although standardised quantitative assess- ments provide valuable information the vast majority do not address the quality of perfor- mance of movement. Partridge & Edwards (1996) suggest that this is partly because of the difficulty in measuring quality in an objective manner. As a consequence, however, assessment of the quality of movement generally remains unstructured in format and subjective in content, relying upon the skill and experience of the therapist to detect and document key issues. This is unsatisfactory since evaluation of the quality of movement is
considered by many physiotherapists to be central in guiding their input, and evaluating their effectiveness in terms of outcome. Attempts have been made to improve this in areas such as gait analysis (for example Lord et al 1998); it is hoped that continued efforts such as these will help to resolve this problem.
Another area of the clinical examination which remains particularly problematic is the objective assessment and description of muscle tone. This is partly due to the paucity of standardised and objective assessment scales that are available for use within the clinical setting. Take for example the Modified Ashworth Scale, a subjective ordinal scale, based upon the assessment of the resistance to stretch imposed passively to the
limb by the examiner (Bohannon & Smith 1987). Despite the fact that this is the most commonly used measure to assess 'spasticity' within the clinical setting, it lacks validity, since it fails to differentiate between the neural and non-neural elements of altered tone (Carr & Shepherd 1998) and to reflect the dynamic nature of tone which is felt by many to be critical to the impact it has on movement and function. Another method that has been used within clinical practice to grade 'spasticity' is the Associated Reactions Scale (Stephenson et al 1998). Unfortunately, despite reasonably widespread use (Haas 1994), this scale has not been evaluated in terms of its relia-
Figure 2.1
Key point diagram describing the severity and
distribution of abnormal tone.
bility, validity, or responsiveness and therefore it is impossible to know whether the information provided is reliable and meaningful. Describing the distribution of abnormal tone has also proven difficult. One method used to achieve this is by means of a 'key point' diagram in which the severity and distribution of abnormal tone, and alignment, is broadly indicated (Fig. 2.1). A search of the literature, however, failed to reveal any evidence to determine the reliability or validity of this method.
findings and formulating a
The power of assessment lies in the ability of the therapist to identify the key problems using a clinical reasoning process. In this process thera- pists must use their theoretical knowledge and clinical experience to analyse and interpret the assessment findings in the context of a wide range of factors, including the patient's diagno- sis, age and co-morbidities. Such an analysis should enable the formulation of a problem list and treatment plan relevant to the patient's indi- vidual needs at the time of the assessment.
findings and developing a
Following assessment there should be a discus- sion of the assessment findings and an explana- tion of the resultant movement difficulties with patients, as well as with others involved in their care. This is a key point at which patients' per- ceptions of their problems, and their expectations with regard to intervention, can be clarified to ensure that the therapist, other members of the team and the patient are all working together towards a common goal. Discussing the findings with other team members is particularly impor- tant with regard to safe and effective methods of handling and moving the patient, and facilitating functional independence.
When developing the treatment plan it is essential to recognise that many issues relating to management impact directly, not only on the lifestyle of the patient but also on that of their
family. From the patients' perspective their needs are always set in the context of their personal life objectives - and thus are intrinsically based on very different views to those of the professional staff concerned with them (Robinson et al 1996). Decisions may therefore become much more than simply a health issue; personal wishes and expectations, as well as social and environmental factors must be taken into account. In some cases this may indicate that no further intervention is required, whereas in others it may result in the development of an extensive and complex pro- gramme of care, involving a number of profes- sionals from within and outside the health care system. This type of discussion begins to set the stage for involving the patient as an active learner and is likely to be beneficial in increasing their adherence to any treatment recommenda- tions (Partridge 1997). The importance of taking the patient's perspective seriously is further emphasised by French (1997), who considers that it is only possible for rehabilitation to proceed successfully if some kind of a consensus between patient and therapist is reached.
Documenting the findings
Written evidence of the assessment findings in a clear, accurate and logical manner is fundamental to the assessment process. It 'is an essential and integral part of care and not a distraction from its provision' (UK Central Council for Nursing, Midwifery and Health Visiting 1993). Effective records not only provide a concrete history of the assessment and intervention programme, but also demonstrate the chronology of events, the factors observed, the response to treatment and the process of clinical reasoning related to the patient's care. This is necessary for a range of reasons that include communication between professionals; monitoring of standards; audit and quality assur- ance; and for medicolegal purposes.
The SOAP format is a widely used system of record keeping (Robertson 1991). SOAP stands for:
they tell the therapist
• Objective - the objective examination under- taken by the therapist, and the treatment provided • Assessment - the therapist's assessment of her findings and of the effectiveness of the treat- ment undertaken; and • Plan - what the therapist plans to do; whether the treatment will continue or will be changed.
It has been suggested that if this system is used effectively, it is extremely beneficial to the clinical reasoning process (Harris 1993) and enables the therapist to provide an adequate explanation of the nature of her contact with the patient for medicolegal purposes (Diamond 1999). Unfortunately there is no simple formula for deciding what to write or how much to write in the records; each individual must use their professional judgement to determine the most significant issues to document. It is likely that the provision of professional guidelines, toge- ther with regular auditing of records within departments, will help to ensure that records are clinically useful and meet the necessary professional standards for legal purposes. Increasingly, health and social services are using 'shared records' in which all health profes- sionals involved in the care of the patient make entries in a single record. In some situations this record may be held by the patient. This reflects the 'patient-centred team approach' that is now generally accepted as best practice. It presents a challenge to the physiotherapist to use non- jargon language that is easily understood by all those who read the record, be they professionals or lay people.
It is easy to describe the need for an initial assess- ment, where the main purpose is to establish a set of baseline data and measurements against which improvement or deterioration may be judged at regular intervals, such as on discharge and follow- up. Less easy to translate is the notion of assess- ment being continually incorporated throughout intervention, a process wherein the therapist mon- itors and responds to the patient in a dynamic
manner from moment to moment. In this approach the therapist is sensitive to both the physical and psychological needs of the patient at any point in time. The specifics of intervention may be altered throughout the session(s) in a variety of ways, such as the method of handling, the level of encouragement or reassurance given or the physi- cal demands placed on the patient. This ongoing and continuous assessment, which enables effect- iveness to be constantly evaluated, is fundamental to skilled intervention.
Health outcomes are the results, or effects, that can be attributed to health care interventions (Ware et al 1993). Measurement refers to the quantification of data, either in absolute or rela- tive terms. It is now widely accepted that deter- mining the effectiveness of an intervention by measuring its effect on outcome provides a basis for evidence-based clinical decision making (Sackett et al 1996). Hobart (1999) emphasises the importance of measuring outcome, stating that 'standardised methods of outcome mea- surement take the guesswork out of evaluation by offering objectivity, quantification, and a means of universal communication. In their absence we are left with only subjective appraisals and personal judgements upon which to base our decisions'.
There has been an increasing interest in the measurement of health outcomes since the 1980s. This was initially precipitated by extensive - technological developments that expanded all aspects of disease management, giving rise to an increase in the variations of clinical practice and escalating costs. As a direct consequence, there has been an ever-increasing demand on clini- cians to demonstrate the benefits of their inter- vention. More recently, the need for evaluation has regained renewed momentum as an empha- sis has been placed on actively involving patients in making decisions about their own health care provision (Hatch 1997). This process requires information to be available to an even wider group of people to enable informed decision making about the relative benefits of different health care interventions.
A framework for measurement
The World Health Organization's model of ill-
ness provides a useful framework and a common terminology for describing and measuring the consequences of diseases and the impact that rehabilitation interventions may have on them (WHO 1980). The original framework, termed
The International Classification of Impairments,
Disabilities and Handicaps (ICIDH), is now widely used as a basis for evaluation within both clinical and research practice. Recently it has been exten- sively reviewed in order to avoid a purely medical interpretation of disablements and to take into account the role of the environment in the disablement process (Ustam & Leonardi
1998). The new terminology of The International Classification of Impairments, Activities and Participations (ICIDH-2, WHO 1997) is:
Impairment describes a loss or abnormality of body structure or of a psychological or physi- ological function. • Activities describe the nature and extent of actual performance in functional activities, at the level of the person. • Participations describe the nature and extent of a person's involvement in life situations in the actual context in which they live, at a societal level. It recognizes the complex relationship between a person's health condition, their impairments and activity restrictions.
Figure 2.2 illustrates how this framework may be applied to physiotherapy practice.
General principles of outcome measurement
The validity of outcome measurement is depend- ent upon the rigour of the measurement process and the validity of its measures (Rudick et al 1996). It is therefore necessary when undertaking an evaluation to consider a number of important factors. These are discussed in detail in the fol- lowing sections.
Determining the purpose of the evaluation
When initially deciding
what to
measure it is
important to be clear about the purpose of the
evaluation and the information you wish to gain. This might be for a number of reasons. You might wish, for example, to routinely gather baseline and discharge data on all patients attending the service, regardless of their dis- order, for the purpose of identifying key infor- mation about the individual, and for service evaluation and audit. Generic disability assess- ment scales such as the Barthel Index (Mahoney & Barthel 1965) or the Functional Independence Measure (Granger et al 1993) are commonly used for this purpose. On the other hand, you may wish to evaluate the impact of a specific intervention on an individual's specific prob- lems. In this case the choice of measure (or combination of measures) may be quite differ- ent. For example, if the purpose was to evaluate the effectiveness of a splinting programme in a patient who presented with loss of joint range due to soft tissue shortening, the most relevant measure might be the measurement of a joint angle using a goniometer (Norkin & White 1975). It is likely that this would be combined with a measure of function relevant to the patient's particular problems, such as the ability
to stand up or to walk. These two examples illustrate how the outcomes chosen may differ according to the purpose of the evaluation. Although a combination of outcomes is often necessary to comprehensively evaluate your intervention, it is important to be selective, remembering that neither yourself nor the patient should be overburdened by excessive measurement. Research studies are better able, in most circumstances, to investigate the effective- ness of interventions in more detail and, where necessary, with more sophisticated equipment.
Selecting relevant outcomes to measure
In many neurological conditions long-term dis- ability is the norm. For this reason outcome mea- surement can be broadly viewed in two ways:
first, the extent to which stated aims of inter- vention are achieved; and, secondly, the extent to which adverse events might occur if the treat- ment is not given. The range of possible out- comes is presented schematically in Figure 2.3. Death is an easy outcome to measure, but this rarely has direct relevance to physiotherapy
Figure 2.2
The ICIDH: a conceptual and operational model for measuring outcome.
Figure 2.3
Range of possible outcomes following brain
trauma (reproduced from Pope by kind permission).
management. More difficult to measure is the success or failure of the longer-term con- sequences of the disease with regard to mor- bidity. Pope (1992) refers to these in terms of 'dynamic success' (for instance the ability to walk again, to regain function, to get back to work); 'static success' (where the patient's condition is well maintained and where secondary complications do not occur); and 'failure' (for instance the development of pressure sores, con- tractures or pain). Bax et al (1988) illustrated the importance of static success in their study exam- ining the health problems of a population of physically disabled young people in the com- munity. Of the 104 subjects studied the secondary complications experienced included contractures of lower joints (59%), deformed feet (25%), urinary incontinence (59%) and pressure sores (33%). Many of these complications are avoid- able and, hence, a successful outcome in terms of static success would have been attained if they had not occurred.
In the majority of cases, however, the aims of therapy are not simply to achieve static success but also to improve function and well-being. For this purpose it is important that the measure- ment of outcome is focussed at the level at which the intervention is intended to effect change. For example, interventions aimed to impact on impairments such as muscle weakness should measure strength; interventions aimed predomi- nantly at improving function should measure function. To be successful, this requires the ther-
apist to have a thorough understanding of the intervention, and to be specific in identifying in advance what the intervention aims to achieve.
Selecting appropriate measures
In selecting which measure to use, a number of factors must be considered. It is not the purpose of this chapter to describe these in detail, but rather to provide an outline of the more important issues. Several textbooks (McDowell & Newell 1996, Wilkin et al 1992, Streiner & Norman 1995) and articles (Medical Outcomes Trust 1995, McDowell & Jenkinson 1996, Fitzpatrick et al 1998) address these issues comprehensively in a more detailed and technical manner.
In brief, in choosing an outcome measure, four key factors should be reviewed.
1. The purpose of the measure.
The instrument
should be relevant to the purpose of your evalu- ation. 2. Clinical utility. To be useful within the clinical setting the measure should be simple, easy to use, accessible and acceptable to the patient. A manual should be available, describing clearly and in detail the standardised procedure in which the measure should be used. Importantly, the measure should not take up more resources than are avail- able, either in terms of its cost or the time taken.
3. Scientific
properties. The
possess three scientific properties:
accurate, consistent, reliable over time, and
reproducible within and between raters
• validity: it should measure what it purports to measure, in the population and within the setting in which it is being used
clinically important change.
4. Standardisation. It is advantageous to choose a measure that is widely known (for example the Medical Research Council muscle strength grading system). Provided that the measure is used correctly, meaningful informa- tion can then be communicated within and between different professionals and different areas of service delivery. This enables uniform
monitoring of the patient's condition over the longer term. This is particularly relevant to many neurological conditions where the person fre- quently accesses a wide variety of services over many years, and hence is reassessed by a number of different people in a diversity of settings. Ideally, the outcome measure chosen should have been comprehensively evaluated and possess all of these attributes. Unfortunately, however, this is often not the case. To date, relatively few of the clinical measures available for measuring move- ment and function in neurological patients have been extensively and rigorously evaluated. It is the responsibility of clinicians and researchers to review critically the outcome measure chosen to determine how well it meets these criteria. This must be considered in the context of the population and the setting in which it will be used. This knowl- edge is essential to enable accurate interpretation of the information gained from the measure.
the process
of measurement is
The process of measurement must be rigorous if the results are to be credible. Measurement at the time of the initial assessment, before a treatment programme has commenced, is essential. The timing of subsequent measurements will vary according to the length of time that it is expected to take for a change to occur. To ensure reliability the assessments should be undertaken in accordance with operational guidelines and the measurement process should be clearly documented. It is im- portant that the measurements are undertaken in similar circumstances if the comparisons made between evaluations are to be valid. For example, the assessment should be consistently undertaken prior to treatment rather than post-treatment when the patient's performance may be negatively affected by fatigue, or perhaps positively affected by the treatment which has just been given.
The primary reason for using outcome measures is to evaluate the success or failure of interven- tion, in a standardised and objective manner. It is
essential that the information generated is used to inform practice. This requires the clinician to be clear about whether the outcome is attribut- able to the intervention given (Sackett et al 1996), and to reflect on and critically appraise the care given. Accurate and meaningful interpretation of the results must be based on a sound under- standing of both the clinical context (e.g. the severity of the condition, the purpose of the intervention) and the measurement process (e.g. psychometric properties of the measures used, timing of the measurement).
Available measures
A large number of outcome measures are avail- able for use in evaluating the outcome of physio- therapy and rehabilitation interventions. Table 2.2 lists some of the measures currently used within the clinical setting. For further informa- tion about these the reader is referred to the orig- inal articles and to a number of textbooks (for example Wade 1992, Bowling 1995) and reviews (for example McCulloch 1998, Sharrack et al 1999) which describe the measures in more detail.
A goal is the object or aim of an action (Locke et al 1981). Goal setting is now widely accepted as a basic principle of rehabilitation practice, and is generally acknowledged as helping to focus the rehabilitation team on the needs of each individual patient (Duff et al 1999). It provides a structured and objective way of planning and documenting progress, and can aid multi- disciplinary collaboration and communication (Schut & Stam 1994). It may be useful in involv- ing and motivating the patient and carers to be active participants in the rehabilitation process. Furthermore, it is increasingly being recognised as a useful means of improving treatment effec- tiveness and as a method for measuring the effectiveness of interventions and for overall programme evaluation (Cott & Finch 1990).
Evidence to demonstrate the benefits of goal setting with regard to improved performance has
been demonstrated in a number of studies (Locke et al 1981, Williams & Stieg 1987, Malec et al 1991). Importantly, Duff et al (1999) showed that the majority of patients in their study considered that goal setting helped them to plan their rehabilitation.
A number of factors have been identified in the literature as being important for effective goal setting. These are outlined in the following sections.
the patient and family
In aiming to address the needs identified by
patients it is key that patients are encouraged,
participate actively in the
goal-setting process (Haas 1993). This is essential to ensure that the goals set are relevant and motivating for the individual. Initially this may be a new and somewhat daunting prospect. The patient may, for example, lack knowledge about their condition, how it may be expected to change, and what physiotherapy has to offer. This may make it difficult for them to be specific about their goals of treatment. Other factors such as pain, depression or cognitive impairment may also make this process more challenging. In general, however, with experience patients usually develop a sense of how relevant their goals are to their needs and how they can become more actively involved in the process. It is the therapist's role to facilitate this by periodically reviewing, negotiating and adjusting the goals to assure their appropriateness throughout the rehabilitation process.
Formulating objective and measurable goals
The process of goal setting starts with a thorough understanding of the problems identified by the initial assessment. Based on this information, goals may generally be broken down into short- and long-term goals. Short-term goals indicate the first objectives to be met as a result of the immediate treatment plan, and provide a series of small specific steps which focus on achieve- ment of the long-term goal. In contrast, the long- term goal generally indicates the expected level of function and independence that the patient will achieve in broader terms. It is important to recognise that patients do not always understand how short-term goals relate to the achievement of the long-term goal; it is often necessary for the therapist to reinforce this link. For example, the patient with an incomplete paraplegia may not recognise a link between a short-term goal of 'consistently achieving safe transfers independ- ently using a sliding board' and their long-term goal of walking independently.
It has been suggested that goals should be appropriate, measurable, achievable and func- tional; i.e. goals should be SMART (Cott & Finch 1990). They should be formulated in small simple steps that are:
Specific - they should be specific and relevant to the individual and to the problem being addressed. Measurable - the degree of accomplishment should be measurable. Achievable - goals should be challenging but achievable. Locke et al (1981) in their com- prehensive review of goal setting, provide a substantial body of evidence to demonstrate that goals can be a powerful motivating or de- motivating force depending upon whether the goals set are specific, relevant and challenging (motivating) or are vague, easy, 'do best' goals (de-motivating). Realistic - the difficulty of the goals should be determined within the limitations imposed by the neurological impairment and the person's wish and ability to change. It is also important to recognise that not all goals need be focused on improvement; goals might also relate to maintenance.
Time limited - a specific time frame for accom- plishment should be agreed. The time frame should be reasonable; even a very relevant goal may become de-motivating if it takes a very long time to achieve.
clear and
It is generally considered
good practice to
ensure that a written copy of the goals is easily accessible to the patient in language that is explicit and understandable. In many services a copy of the goals is given to the patient. Writing goals that fulfil the SMART criteria can be extremely challenging. A helpful framework is that each short-term goal should have four components:
Who will perform the behaviour - this will
usually be the patient, but could also be the carer. An observable behaviour - what they will do.
How they will do it - to what standard
behaviour will be performed, the aids used, level of assistance required, consistency, the setting in which it will occur and the level of safety. These issues need to be specified to ensure the goal is measurable. The time scale for achievement with precise dates for achievement.
Awareness of factors achievement
may impact on goal
Factors such as cognitive and physical function, mood, fatigue, carer involvement and environ- mental factors are important to consider if realistic goals are to be set. By identifying and recording reasons for achievement and non-achievement of goals, the team is able to reflect on their practice and alter it as needed. In some services integrated care pathways have proven useful for ensuring that regular auditing of goals is incorporated within clinical practice (Rossiter et al 1998).
Providing feedback
There is evidence to suggest that feedback is important in improving performance (Locke et al
1981). This may be in the form of feedback about the achievement or non-achievement of goals, or feedforward about how hard the person will need to work to achieve the goal. There is no set formula for determining the frequency of feed- back; a variety of different systems exist which are tailored to the needs of the service and to the individual (for example Malec et al 1991, Duff et al 1999). It is important, however, that members of the multidisciplinary team meet on a regular basis to review and set additional goals. In some departments this directly involves the patient, while in others it does not. Within the social science literature, the evidence remains equivocal as to whether direct participation in setting goals leads to better task performance or greater goal commitment (Locke et al 1981). Unfortunately,
paucity of research to determine
whether this is the case in rehabilitation (Wade
The issues of measurement and outcome in physiotherapy are recognised as being one of the greatest challenges of the clinical effective- ness agenda (Bury & Mead 1998). This requires physiotherapists to incorporate objective stan- dardised assessment, and rigorous evaluation of the effectiveness of interventions, as part of their daily clinical practice. It requires a willing- ness to keep an open mind, to remain objective and to take a risk in allowing our beliefs to be tested.
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Introduction 35
Features of normal movement
Normal postural tone
Reciprocal innervation
Sensorimotor feedback and feedforward
Balance reactions
Nerve-muscle interaction
An approach to the analysis of posture and movement 46
Rotation of body segments
Postural sets
Key points of control
Midline - the alignment of body segments
Analysis of specific positions
Normal movement or activity may be considered
Supine lying
to be a skill acquired through learning for the
Prone lying
purpose of achieving the most efficient and eco-
nomical movement or performance of a given
task and is specific to the individual. Motor control concerns the nature and cause of move-
Analysis of movement sequences
ment and is dependent upon the interaction of
Moving from supine lying to sitting
Moving from sitting to standing Walking 56
both perceptual and action systems, with cogni- tion affecting both systems at many levels
Upper limb function
(Shumway-Cook & Woollacott 1995).
Conclusion 63
chapter is to describe
References 64
aspects of posture and movement which relate to the normal adult population. Many com- ponents of movement are consistent and these form the basis of this analysis of normal behav- iour. Similarities and differences which arise within the normal adult population will be discussed throughout this chapter as they relate to specific postures or movement com- ponents.
The emphasis on regaining 'normal move- ment' following neurological damage has been challenged by Latash & Anson (1996). Their provocative but fascinating article suggests that the restoration of function is an adaptive process, dependent upon the residual capability of a damaged nervous system. Comparison is made between each end of the spectrum of 'normal movement', highlighting the disparity between the clumsy individual and the elite sports person. Although ordinary mortals may admire the athlete capable of high jumping in excess of 6 feet, how many 'normal' individuals consider a
Fosbury flop, the high jump technique, to be a fundamental part of their physical repertoire? A knowledge of normal movement has been described by many authors as a basis for treat- ment of the neurologically damaged patient (Davies 1985, Carr & Shepherd 1986, Galley & Forster 1987, Bobath 1990, Davies 1990, Lynch & Grisogono 1991). A wide range of different clini- cal presentations exist in patients with neurolog- ical dysfunction and, consequently, different aspects of movement impairment will be demon- strated. For example, a patient with acquired brain injury or one with multiple sclerosis may present with hypertonus or ataxia or indeed a combination of the two. The clinical presentation and selection of the most appropriate treatment intervention may only be accurately assessed on (a) the basis of an extensive knowledge of normal movement and (b) recognition of the severity and duration of the neurological damage which may necessitate compensatory strategies.
The main remit of physiotherapy is to enable patients to attain their optimal level of function with regard to effectiveness and efficiency of movement. In the acute stage of management emphasis is on the recovery of normal movement strategies, with the patient regaining the ability to perform tasks in the same way as prior to the onset of their neurological damage. However, for patients with more chronic, established condi- tions, compensatory/alternative strategies, may need to be adopted to accomplish the task.
It is not within the scope of this chapter to discuss the neuropsychological impairment which may be an integral component of the patient's disability. The implications of behavioural, per- ceptual, cognitive or memory dysfunction are described in Chapter 4, and movement cannot be considered to be a separate entity from these aspects. Lack of emphasis on these neuro- psychological aspects in this chapter in no way reflects any lack of recognition of their importance in the total picture of neurological rehabilitation.
Normal movement is dependent upon a neuro- muscular system which can receive, integrate
and respond appropriately to multiple intrinsic and extrinsic stimuli. It is controlled not only by central commands and spinal activity but also by functional and behavioural aspects which influ- ence posture and movement. The central and peripheral systems interact extensively during the execution of motor plans and comprise sets of feedforward commands for complex motor actions. These are learned from successful, pre- vious motor performance (Brooks 1986). In order for this interaction to be effective in producing normal movement, key components should be considered.
Both neural and non-neural mechanisms con- tribute to the generation of muscle tone or stiff- ness in individual muscles. In the assessment of patients with neurological impairment, neurolo- gists define muscle tone in an operational manner as the resistance to movement when the patient is in a state of voluntary relaxation (Davidoff 1992). Perhaps more appropriately for therapists, postural tone or the activity in muscles when counteracting the force of gravity, has been described as the state of readiness of the body musculature in preparation for the mainte- nance of a posture or the performance of a move- ment (Bernstein 1967).
Normal postural tone enables an individual to:
maintain an upright posture against the force
of gravity vary and adapt to a constantly changing base
of support allow selective movement to attain functional skills.
Postural tone is adaptable and varies through- out different parts of the body in response to desired goals. Brooks (1986) describes the intri- cacy of the golf swing to illustrate the synchro- nous coordination of posture and movement. The stance of the golfer must be such as to afford stability during the arm swing by setting the stance muscles at the proper steady tensions, while at the same time setting the readiness to respond to stretch of contracting muscles. The
tone of the trunk and lower limbs must provide adequate postural support for the moving parts before a successful swing can be accomplished. From this example of a golf swing it can be seen that the distribution and intensity of postural tone can be influenced by the size of the base of support. From a mechanical perspective, this is the area within the boundaries of each point of contact with the supporting surface. However, of rele- vance to patient treatment is the ability of the indi- vidual to respond and interact appropriately with this support, as described in Chapter 6. The larger the base of support and the lower the centre of mass in relation to the supporting surface, the less effort is required to maintain position and stability. For example, lying provides a far greater base of support than does standing and therefore is the more stable position. Postural tone is therefore nor- mally lower in lying than in standing.
These factors are relevant in the choice of posi- tion in which to treat a patient. Many patients following neurological damage spend a consid- erable proportion of time in lying and, depend- ing on the extent of their disability, may be unable to stand independently. Recruitment of muscle activity in lying, particularly for patients with low tone, is often difficult. Considerable effort is required to overcome the force of gravity and, in functional terms, it is a position which, in normal circumstances, is rarely used for activities of daily life. For this reason, it is often more appropriate for the patient with low tone to be placed in a more upright position with a reduced base of support and the centre of mass higher in relation to the supporting surface. However, careful preparation is essential before placing these patients in standing. Effective support must be given to ensure alignment of body parts and thus minimise inappropriate and unneces- sary compensation.
According to Bobath (1990) reciprocal innerva- tion is the graded and synchronous interaction of
agonists, antagonists and synergists throughout the body. Marsden (1982) describes this inter- action when:
starting from an initial posture, the limb or digit is repositioned in space by activation of the prime moving muscle, the agonist; at the same time, the activity of antagonists must be adjusted, and the actions of both the agonists and antagonists around a joint must be complemented by appropriate changes in activity in synergistic muscles. Not only do simple synergies fixate a joint to allow action of the prime movers, there must also be appropriate contraction of proximal fixating muscles so as to adjust the trunk to maintain balance.
The physiological basis of reciprocal inner- vation is described in Chapter 1. Reciprocal innervation occurs during discrete, selective movements, for example of the fingers during fine manipulation, and also in postural control. It may be considered to be an integral part of balance. The constant postural adjustments and interaction between muscle groups provides the automatic adaptation of the body in response to the functional goal and to changes in the environment.
When standing, the interaction of muscle groups, primarily those of the pelvis, trunk and legs, is dynamic with constant adjustments occur- ring to enable mobility within the base of support. This dynamic feature frees the arms for selective movement. It is suggested that the nervous system combines independent, though related muscles, into units called muscle synergies. This is the functional coupling of groups of muscles such that they are constrained to act together as a unit, thereby simplifying the control demand of the CNS (Shumway-Cook & Woollacott 1995).
The postural adjustments that occur automati- cally, prior to, during and after the performance of a movement provide:
• equilibrium by maintaining
gravity within the base of support; these adjustments occur during the performance of a selective movement such as reaching forwards with the arm and when there is an application of an external force to the body (a perturbation) • body stability; that is the postural adjustments govern the position of given segments such as
the head or trunk (Massion 1992, Soechting & Flanders 1992).
Potentially destabilising movement is preceded by activation of postural muscles, called anticipa- tory postural adjustments, which serve to com- pensate in advance for changes in equilibrium or posture caused by the movement. These prep- aratory postural responses occur both to preserve balance in standing (Cordo & Nashner 1982) and to stabilise posture before an arm movement (Massion & Woollacott 1996, Wing et al 1997).
Patients with abnormal tone following neuro- logical damage illustrate impaired reciprocal innervation. This may be as a result of hypotonus causing inadequate stability due to reduced activity, or of hypertonus where there is exces- sive and stereotyped activity preventing these tonal adaptations. In the latter case, co- contraction may become static and constant. Dominance of the hypertonic muscles prevents interaction between the opposing and com- plementary muscle groups, resulting in a static fixation rather than a dynamic stability (Massion
The ability to co-activate agonist and antago- nist muscles is also important in terms of trunk control. Functional tasks such as eating and dress- ing require constant adaptation of muscular activ- ity with regard to the trunk and pelvis. Reaching to pick up a cup from a table requires stability within the trunk and of the pelvis in order to transfer weight and accomplish the task most efficiently (Moore et al 1992). A disabled person with a neurological impairment adversely affect- ing trunk and pelvic stability may be able to adapt and perform the function, but the effort required may be substantially greater and compensatory strategies may be used.
Altered reciprocal innervation is a feature in patients with cerebellar lesions. Complex motor programmes involving postural adjustment in support of the focal movement of the limb are impaired (Diener et al 1990, 1992). This is illus- trated in the finger-nose test which is used to determine the severity of ataxia. It is often consid- erably easier for the patient to coordinate arm movement with the body supported and the elbow resting on a firm surface than with the body and arm unsupported (Haggard et al 1994). In this way, the movement is broken down to the more simple task of elbow flexion and extension and is there- fore less dependent on proximal stability.
Figure 3.1
Cartoon summary highlighting the motivational function of the limbic system in motor control. Direct connections
are indicated by heavy arrows and indirect connections by light arrows. Feedforward connections are represented in (A) and
feedback between equivalent systems in (B). (Reproduced from Brooks 1986 The neural basis of motor control, Oxford University Press, with kind permission.)
Postures and movements are guided by a mix- ture of motor programmes and sensory feedback. Motor programmes have been described as a set of muscle commands which are structured before a movement sequence begins and that allow the entire sequence to be carried out uninfluenced by peripheral feedback (Keele 1968). Feedback brings the programme commands up to date with their execution and corrects errors (Brooks 1986) (Fig. 3.1). Control of posture and movement requires ini- tiation and planning at the highest level, control and updating from the middle level and execu-
tion and regulation of the task at the lowest level. However, it must be stressed that interaction between these levels is constant and ongoing, providing information in both directions (see Chapter 1). Movement skills are constantly reinforced and refined by variable repetition, the CNS being ever sensitive to both intrinsic and extrinsic sensory information, which is assimilated to produce effective activity. Motor learning is therefore an active process. This is of particular
of patients
rological disability. Patients who are unable to move cannot reinforce their motor programmes and the maxim 'use it or lose it' may therefore apply. There is evidence of extensive functional and structural plasticity in the adult cerebral cortex. Functional maps in sensory and motor cortex are dynamically maintained by use and are altered by central and peripheral patho- physiological disturbances (Nudo 1999). Everyday activities such as walking and getting out of bed require little conscious effort once they become established movement pat- terns. The objective is to achieve a functional goal, as opposed to having to consider how one accomplishes each stage of the task. In contrast, the learning of new skills, such as how to drive a car, will initially involve considerable concentra- tion until the movement patterns become estab- lished, after which time the task becomes relatively automatic (Schmidt 1991a).
Normal movement is dependent upon con- stant interaction of neural structures within the CNS. This neural activity may be considered a cyclical event during the performance of normal movement which reinforces movement patterns.
Any interruption in this cycle of events will affect the outcome. If there is abnormal postural tone as a result of neurological damage, there may be dis- ordered movement or a limited movement reper- toire, producing an abnormal sensory input to
is produced by effort and/or compensation,
which in turn produces abnormal movement and abnormal postural adaptation (Fig. 3.2).
Sensory-motor integration in terms of continual feedback and feedforward is essential in the learning experience of any individual. By enabling the patient to move in a more normal way, effective motor programmes may be regained. Motor learning is a set of processes associated with practice or experience, leading to relatively permanent changes in the capability for skilled performance (Schmidt 1991b). The only way motor learning may be clinically observed is in a change in the patient's functional capability. The performance at the end of practice is not an indi- cator of the degree of learning. In fact certain
factors which improve performance at the end of practice do not necessarily lead to long-term learning or carry-over (Schmidt 1988). Shumway-Cook & Woollacott (1995) provide an excellent review of the theories of motor con- trol. They propose that movement emerges from an interaction between the individual, the task and the environment in which the task is being carried out and that movement is the result of a dynamic interplay between perceptual, cognitive and action systems.
Postural or equilibrium control is a sensorimotor task requiring the coordination of sensory infor- mation with motor aspects of postural control and is the foundation for all voluntary skills. Almost every movement is made up of both pos- tural components which stabilise the body and the prime mover components which relate to the particular movement goal (Massion & Woollacott
For the purpose of assessment and treat- ment, Bobath (1990) differentiated between three groups of automatic postural reactions. These were referred to as righting, equilibrium and protective/saving reactions. Although many ther- apists continue to make use of this terminology, there is some confusion, particularly with regard to righting reactions. As discussed in Chapter 1, the righting reactions are observed only in developing infants and in specific animal preparations. In the mature adult, they become integrated into more complex equilibrium reactions (Bobath 1990) and division between the two is impossible (Bryce
Clinicians refer to righting reactions as they relate to the alignment of body segments to each other and to the environment and in the per- formance of sequences of movement such as rolling, sitting up and lying down (Davies 1985, Edwards 1998). However, when con- sidering posture and balance in a broader context, this may be considered to be an artificial divide.
have been attributed to postural
The maintenance of the alignment of body
posture with a vertical relationship between body segments to counteract the forces of gravity to attain an upright stance. The maintenance of equilibrium by keeping
the body's centre of mass within the base of support while a movement or task is being performed. The interaction between perception and action
systems to maintain bodily orientation to the environment. This provides an internal pos- tural image or postural body schema, which is monitored by multisensory inputs. The organisation of body segments according to the function of the task and the dynamic adjustment of joint stiffness during the move- ment (Massion & Woollacott 1996).
Unpredictable forces that disturb equilibrium in standing produce automatic, coordinated responses of muscles across a number of body segments that serve to maintain posture. The anticipatory postural adjustments have been described above in the context of reciprocal innervation (see page 38). This 'pre-tuning' of sensory and motor systems for postural demands is based on previous experience and learning and is more variable the slower the movement (Horak et al 1984). As less stabilisation is required during slower movement, the prepara- tory muscle activity is not programmed as con- sistently as with more rapid movement. In addition, if a perturbation is applied in standing when the hand is in contact with a fixed sup- port, the automatic postural response includes activation of the muscles of the arm and hand to help to restore balance (Cordo & Nashner 1982). This adaptive postural control therefore involves modifying sensory and motor sys- tems in response to changing and environ- mental demands (Shumway-Cook & Woollacott
Characteristic patterns of synergic muscle activity have been described which underlie movement strategies critical for postural control in standing (Nashner 1977, Horak & Nashner 1986). These are referred to as the ankle, hip and stepping strategies and are used in both a feed-
back and feedforward (anticipatory) manner to maintain balance. The ankle strategy is that which is used during quiet stance, when the perturbation to equilib- rium is small and the support is firm. The hip strategy is used when the perturbation to balance is faster and greater and when the support surface is pliant or smaller than the feet, such as when standing on a beam. Movement at either the ankle or hip is dependent upon full range of movement and strength of muscles acting over these joints. The stepping strategy is called into play when the perturbation is such as to displace the centre of mass outside the base of support and a step or hop is required to restore alignment.
In addition to the ability to generate force to control the position of the body in space, effective postural control is dependent upon sensory information from visual, somatosensory and vestibular systems. Visual inputs provide a reference for verticality and head motion; the somatosensory system provides information regarding the body's position in space with refer- ence to the supporting surface and the relation- ship of body segments to each other; and the vestibular system provides information about the position and movement of the head. It is sug- gested that the nervous system might 'weight' the importance of somatosensory information for postural control more heavily than visual or vestibular inputs (Shumway-Cook & Woollacott
Clinical application
When a movement is performed, postural con- trol is provided by segmental adjustments which compensate for the displacement of the centre of mass caused by the moving segments (Massion 1992). Changes in the location of the centre of mass necessitate preparatory and continuous postural adjustments during any movement, and even the smallest alteration has to be countered by modifications of tone throughout the body musculature (Bobath 1990).
Although the limbs frequently adopt a posi- tion of asymmetry in relation to each other, there is invariably predominant symmetry of the
trunk, pelvis and shoulder girdles. It is important to recognise that, although many positions are asymmetrical in normal movement, this asym- metry is transient and interchangeable through symmetry. In contrast, patients with neurological disability are observed to have asymmetry imposed by weakness or abnormal movement strategies. For example, if a patient with a dense left hemiplegia attempts to roll towards the right side, the affected side may be unable to initiate or participate in the movement and tends to be left behind. Realignment of body segments on completion of the movement is often impaired.
The increased variability in the anticipatory postural adjustments with slower movements and the use of motor pathways controlling arm and hand movement when support is provided has implications in the treatment of patients with neurological damage. Many patients will be unable to move as quickly as normal subjects and changes in the postural adjustments may be related more to the speed of movement as opposed to the pathology. Similarly, some patients may require assistance or mechanical aids to enable them to stand and walk. The support offered by the therapist or, for example, a walking frame will influence the postural adjustments. While it is important to facilitate a more normal posture or movement, it may be of equal value to give the patient the opportunity to correct his own posture. If the therapist con- stantly supports the patient, the postural adjust- ments will always be dependent on this support (Edwards 1998).
Postural control requires all degrees of recipro- cal innervation through the coordinated response of neuromuscular excitatory and inhibitory control to enable postural holding patterns and those for selective movement to operate effect- ively (Mink 1996). This interaction between opposing and complementary muscle groups is the basis for the maintenance of posture and the performance of selective movement. The ability to maintain equilibrium in a great variety of posi- tions provides the basis for all the skilled move- ments that are required for self-care, work and recreation (Davies 1985).
Control of movement is dependent upon the interaction between the nervous system and the musculoskeletal system. While the central nervous system generates patterns of movement or motor programmes, their effectiveness is dependent upon the viscoelastic properties of muscles and the anatomical alignment of bones and joints. This section discusses the nerve- muscle interaction which may be affected by neurological impairment.
Neural components
The motor unit. The combination of the motoneurone, its axon and the muscle fibres that it innervates is known as the motor unit or 'final common pathway'. It is activated according to the sum of excitatory and inhibitory inputs and it is through this route that all processing in the CNS is finally transformed into movement (Rothwell 1994, Vrbova et al 1995).
Each muscle fibre is supplied by only one motoneurone but each motoneurone supplies many muscle fibres. The number of fibres sup- plied by a single motoneurone is referred to as the innervation ratio. Smaller muscles such as the intrinsic hand muscles have a lower innervation ratio - each motoneurone supplying fewer muscle fibres - and it is suggested that there is at least a moderate correlation between innervation ratio and the ability to finely grade muscle force (Enoka 1995).
Muscle fibre type. Skeletal muscles are com- posed of a variety of functionally diverse fibre types. They are dynamic structures capable of changing their phenotypic profile according to the functional demands placed upon them. This adaptive responsiveness is the basis of fibre type transitions (Pette & Staron 1997).
There are three basic fibre types:
Slow-twitch oxidative (SO) or type I. These are innervated by small motoneurones and have a small fibre diameter. They are slow to contract, generate a small force and are very resistant to fatigue.
• Fast-twitch oxidative glycolytic (FOG), or type IIA. These have a medium-small fibre diame- ter, are fast contracting, generate an intermedi- ate force and have some resistance to fatigue. • Fast-twitch glycolytic (FG) or type IIB. These have motoneurones with large cell bodies and have large-diameter axons. They are fast con- tracting, generate a large force and fatigue readily (Rothwell 1994).
The characteristics of the three main fibre types are summarised in Table 3.1. However, other fibre types have been reported in both animal and human studies. There are reports of an intermediate type IID/X in skeletal muscle (Vrbova et al 1995, Pette & Staron 1997) and it is suggested that a considerable percentage of hybrid fibres are present in normal adult muscles (Pette & Staron 1997).
It may be that there is some misclassification of fibre types in human muscles in that type IIB fibres are more similar to the rat IIX than to the rat type IIB (Ennion et al 1995, Pette & Staron 1997, Goldspink 1999a). Hill (1950 as cited by Ennion et al 1995) hypothesised that because the muscles in larger animals are longer, with more sarcomeres in series, their intrinsic velocities of shortening would have to be lower than those of small animals; otherwise, the rate of force devel- opment would be unsustainable. It is suggested that the type IIB fibre type expressed in rodents is associated with too high an intrinsic velocity for humans and is therefore not expressed. This difference between type IIB fibre type in rats as compared to humans was described most succinctly by Goldspink (1999b). If humans moved at the same speed as rodents, the ballistic movements of the limbs would be so extreme as to cause them to become detached from the torso.
A muscle does not consist of a homogenous population of muscle fibres; there are several different fibre types within a muscle, each of which has different mechanical properties. The range of operation of the whole muscle is extended beyond that of any one fibre type alone. A predominance of one fibre type gives the muscle its characteristic properties (Rothwell 1994).
Muscles with predominantly SO fibres partici- pate in longer-lasting but relatively weak con- tractions, such as in postural control, whereas those with predominantly FG fibres generate large forces but are more readily fatigued. A sporting analogy is to compare the marathon runner with the sprinter. The marathon runner has endurance, due to a predominance of SO fibres, whereas the sprinter, with predominantly fast-twitch muscles, demonstrates explosive power but which is of short duration and there- fore cannot be sustained.
Gene expression/fibre type determination. Fibre phenotype is dependent not only on neural activ- ity but also to a large extent on mechanical factors, specifically a combination of stretch and muscle activity (Lin et al 1993, Goldspink 1999a). All muscles stay phenotypically fast unless they are subjected to stretch and force generation. For example, in rats, soleus, with predominantly slow oxidative fibres, if immobilised in a shortened position, subjected to hypogravity or denervated by spinalisation, reverts to expressing the fast gene (Goldspink et al 1992). Furthermore, experiments have shown that the number of SO fibres in the rat soleus muscle increases after birth as the animal uses this muscle for support. If this supporting function is negated by hind limb suspension, the increase in slow-twitch fibres is arrested or fails to occur. A similar finding results following tenotomy of soleus preventing it from being stretched. The contractile speed of the tenotomised muscle becomes fast although the innervation is unchanged (Vrbova et al 1995, Pette & Staron 1997). The main regulation in the expression of the slow phenotype seems to depend on the repres- sion of the fast-type as much as activation of the slow-type genes (Goldspink et al 1992).
Development, innervation, increased and decreased neurological muscular activity, over-
Figure 3.3 Schematic representation of major factors affecting sequential fibre-type transitions. (From Pette & Staron 1997 with permission.)
loading and under-loading, hormones and ageing have all been shown to be influential in determining the phenotypic expression of skele- tal muscle fibres. In general, activity and loading result in fast-to-slow fibre type transition and decreased neuromuscular activity or load cause transitions from slow-to-fast (Pette & Staron 1997, Pette 1998) (Fig. 3.3). Certainly in animal muscle, on which most experiments have been conducted, this fibre type transition is a graded event (Vrbova et al 1995) The nerve has a powerful influence on the properties of muscle fibres. Nerve transfer in animals shows fast muscles supplied by a slow nerve become slow contracting, and slow muscles supplied by a fast nerve become fast acting, although the cross-innervated muscles are not as slow or as fast as predicted and this nerve trans- fer does not produce a complete change in phe- notype (Vrbova et al 1995). Muscles may alter their characteristics depend- ing on their usage (Dietz 1992). FG muscles will readily hypertrophy when they are recruited and overloaded during sustained exercise training, as under normal conditions, compared with the SO muscles, they are recruited relatively infre- quently. Conversely, although the SO muscles may also hypertrophy, this will be to a lesser extent as they already participate to a more
maximal degree in postural control (Rothwell 1994). However, exercise alone cannot radically change fibre type composition or contractile characteristics. During exercise, the motor units are still recruited in an orderly fashion although activated more often and the sequence of recruit- ment of motor units remains the same, there being no evidence that the motoneuronal proper- ties which influence the pattern of firing are changed by increased use (Vrbova et al 1995).
Recruitment order. The recruitment order of a motor unit depends on the size of its motoneu- rone. Motoneurones with the smallest axons are excited before those with larger axons: i.e. in the order SO > FOG > FG (Henneman et al 1965 as cited by Rothwell 1994). In this way skeletal muscles are well designed and matched for highly specific functions in the orchestration of any movement by the CNS (Rothwell 1994, Vrbova et al 1995). Postural muscles, which are made up predominantly of SO muscle fibres and participate in long-lasting but relatively weak contractions, are recruited before those which are predominantly fast-twitch and generate larger forces but are more readily fatigued.
For example, it has been shown with electro- myographic (EMG) studies that postural muscle fibres such as those of soleus, are activated almost continuously during standing and walking where- as fibres in other skeletal muscles are activated only 5% of the time (Goldspink 1999a). With a common input to the medial gastrocnemius and soleus motoneuronal pools, soleus, which has a predominance of SO muscle fibres, is always recruited before gastrocnemius, which has a greater percentage of fast-twitch fibres. It is not only active during tonic contractions: even in jumping, soleus is maximally active but, in this case, the gastrocnemius produces the most force (Rothwell 1994).
Non-neural components
Contractile properties of muscle. Skeletal muscle fibres are gathered together into bundles called fascicles which are surrounded by a connec- tive tissue sheath. The internal structure of the muscle fibre is complex, with the main elements
being the myofibrils which constitute the contrac- tile machinery of the muscle. Each myofibril con- sists of longitudinally orientated filaments called myofilaments, the bulk of which are composed of two proteins, actin and myosin. Actin and myosin filaments overlap in the sarcomeres when a muscle contracts. This is referred to as the 'sliding fila- ment' hypothesis. The critical stage of force gener- ation is rotation of the myosin head. This causes the filaments to slide over one another if they are free to move, producing an isotonic contraction, or otherwise an isometric force is generated.
At rest, the concentration of calcium in the sarcoplasmic reticulum is very low, so the major- ity of actin-myosin bonds remain unformed. The release of neurotransmitter at the neuromuscular junction initiates an action potential along the cell membrane of the muscle fibre, causing a release of calcium from the sarcoplasmic reticu- lum into the sarcoplasm. This process allows for the formation of actin-myosin bonds. Calcium is then actively pumped back into the sarcoplasmic reticulum and the contraction ceases.
Mechanical properties of muscle. There are three elements in the mechanical behaviour of muscle. The contractile element has its own mechanical properties, viscosity and stiffness, which change with the level of muscle contraction. The contrac- tile mechanism resides in the interaction between the actin and myosin filaments. The series elastic element lies in the tendinous insertions of the muscle and in the actin and myosin cross-bridges themselves, and transmits the force of contrac- tion. The parallel elastic element resides in the sarcolemma of the muscle cells and in the sur- rounding connective tissue. This both distributes the forces associated with passive stretch and maintains the relative position of fibres (Goldspink & Williams 1990, Rothwell 1994). The contractile element actively generates muscle force, whereas the series and parallel elastic ele- ments are passive components, acting as mechanical springs.
There are two important relationships which influence the control of muscle contraction. The first is the length-tension relationship whereby, as the muscle length is increased, the force exerted rises. The tension is due not only to the activity of
the contractile element but also to passive stretch of the non-contractile elements. The force pro- duced therefore differs depending on the muscle length, maximum work being performed by a muscle shortening at intermediate muscle lengths. The example cited by Rothwell (1994) is the extended position of the wrist while the fingers flex powerfully on to an object in the palm of the hand. The power of the grip is substantially weak- ened with a more flexed wrist position. This may be significant following stroke, where flexor hypertonia is often predominant in the upper limb. Many people are unable to extend the wrist, with a resultant decrease in grip strength and impairment of manipulation skills.
The second is the force-velocity relationship in that the rate at which a muscle can shorten depends upon the force exerted: the greater the resistance to movement, the more the velocity of movement is decreased. The length-tension and force-velocity con- tribute to compensation for unexpected disturb- ances. A sudden increase in load can produce increased muscle tension not only through reflex pathways but also by the nature of the length- tension characteristics of the muscle. Even in the deafferented man, the force output adjusts although not to the same extent as normal (Rothwell 1994). The elastic compliance of muscle is dependent upon the concentration of collagen, a major com- ponent of intramuscular connective tissue. This concentration is higher in slow-twitch as opposed to fast-twitch muscle and is reflected in the passive length-tension curves which show that fast-twitch muscle has a higher compliance. Experiments with rats have shown that slow-twitch postural muscles are particularly sensitive to immobilisation. The intramuscular connective tissue increased more rapidly in the immobilised soleus than in gastroc- nemius, which is composed primarily of fast- twitch fibres, and this was more prevalent when the muscles were held in a shortened position (Given et al 1995).
The force generated by a muscle is dependent upon the number of cross-bridges which can be engaged between actin and myosin filaments and this in turn depends on the overlap of these
filaments in the sarcomere. The number of sarcomeres in series determines the distance through which a muscle can shorten and regula- tion of the sarcomere number is considered to be an adaptation to changes in the functional length of muscle. If a muscle is immobilised in a short- ened position, there is a reduction in the number of sarcomeres and conversely, if a muscle is immobilised in a lengthened position, there is an increase in the number of sarcomeres (Herbert 1988, Goldspink & Williams 1990). However, in animals, the changes in sarcomeres have been shown to be age dependent, the young adapting to a fixed lengthened state by lengthening the tendon as opposed to adults adapting with sarcomeres growing longer under the same conditions (Whitlock 1990). The interaction between the actin and myosin filaments gives the muscle a certain resting tension and short-range dynamic stiffness. This plastic behaviour or stiffness within the muscle fibre itself is known as thixotropy (Hagbarth 1994); this is an engineering term which is used to describe the dynamic viscosity of fluids. When applied to muscle, thixotropy has been attributed to abnormal cross-bridges between actin and myosin filaments, producing an inherent muscle stiffness (Sheean 1998).
Clinical implications
Neural activity is a major factor in influencing the characteristic properties of skeletal muscles (Dietz 1992). Changes in function imposed by neurological impairment may produce muscle fibre type transformation and/or change in muscle fibre type distribution that is dependent upon the amount and the pattern of neuronal input (Jones & Round 1990, Cameron & Calancie 1995). Within the upper motor neurone syn- drome both fibre type transitions have been reported (see Chapter 5). Prevention or reversal of denervation atrophy depends on the capacity of the nerves of surviving motoneurones to sprout and reinnervate as many denervated fibres as possible. As a result of sprout- ing, each motoneurone supplies an increased number of muscle fibres. The innervation ratio is
therefore increased, each motoneurone supplying more muscle fibres, leading to a decrease in selec- tive movement (Gordon & Mao 1994). Although exercise to improve muscle strength is recommended, strenuous activity of partially denervated muscle can lead to an irreversible increase in weakness (Bennett & Knowlton 1958). It is suggested that, in order to avoid overwork weakness, there must be:
a balance between rest and activity
strengthening programmes specific to the
patterns of weakness
grammes for normal cardiovascular responses to exercise (Curtis & Weir 1996).
In patients with neurological disability, muscles may be constrained in a shortened position due to the prevalence of abnormal tone. There is loss of sarcomeres and a reduction in muscle fibre length with an increased resistance to passive stretch. This alters both the length-tension and force-velocity relationships of muscle contraction, and optimal force production is impaired. Sustained stretch of shortened structures may go some way to improv- ing the biomechanical advantage and enabling more effective activation of muscle, a factor noted in clinical practice. Many patients automatically elongate shortened muscles and report greater ease of movement following sustained stretch. Splinting may also be used as a means of imposing sustained stretch. The advantages and dis- advantages of this intervention are described in Chapter 10.
This section aims to identify key components relating to the analysis of positions and of move- ment sequences.
planes of movement. The importance of rotation in the maintenance of posture and performance of movement is discussed by many authors (Knott & Voss 1968, Galley & Forster 1987, Bobath 1990). Certainly, loss of rotation and arm swing are noticeable aspects of impaired movement, charac- terised in, for example, the patient with Parkinson's disease (Marsden 1984, Rogers 1991).
This interplay between flexion and extension can be illustrated when observing the develop- ment of rolling in children. At birth, the child is predominantly flexed, with some extension at the neck allowing for rotation of the head. Slowly over a period of 3-4 months, the child learns to lift his head when in prone, support on his forearms and, by 6 months, push up on to extended arms, devel- oping extensor activity throughout the body. The initial movement of the child from prone to supine is a crude, gross movement rather than a con- trolled activity. As the child becomes more confi- dent in pushing up on to extended arms, he begins to look around, and in so doing transfers his weight from side to side. Over-exuberance takes the centre of gravity outside of the base of support and he falls on to his back. This first experience of movement from prone to supine is an illustration of the innate lack of coordination between exten- sion and flexion. Over the following months, rolling from prone to supine and from supine to prone, is refined as a direct integration of extensor and flexor activity. The weight-bearing side actively works against the surface as the body rotates around its axis, providing stability for the movement (Alexander et al 1993). The more intri- cate skill, of getting from the floor up into sitting, is only achieved when the child has developed the necessary level of neuromuscular control.
Rotation within the trunk and of the prime movers in the limbs is fundamental for the per- formance of functional skills such as eating, dressing, writing and walking. Any alteration in the distribution of tone, either excessive flexion or extension, will result in impaired rotation and subsequent impoverishment of movement.
'Postural sets' is a term used by Bobath (1990) to
describe adaptations of posture or adjustments
which precede and accompany a movement. They can be viewed as anticipatory postural adjustments which occur prior to the disturbance of posture and equilibrium resulting from the movement (Massion 1992). When considering these responses in relation to activity of the arm, Cordo & Nashner (1982) observed that, with a voluntary arm movement, the leg muscles involved in postural control are activated prior to the prime movers. The dura- tion of the anticipatory postural adjustments increases with the load to be raised by the arm (Lee et al 1987). These authors suggest that the preparatory adjustments are not specifically related to balance control but that they also directly provide additional force for performing the movement. These anticipatory postural adjustments also serve to stabilise the position of segments such as the head, trunk or limbs during movement performance (Massion 1992).
A practical example of this preparation for movement and the control during performance of the movement is in jumping into the deep end as opposed to the shallow end of a swimming pool. When jumping into deep water, contact with the bottom is cushioned by the volume and depth of the water. The legs tend to be held straight as the feet search for the bottom of the pool. Conversely, when jumping into shallow water, the legs remain slightly flexed in prep- aration for the impact of hitting the bottom. On making contact with the bottom of the pool, the knees give, cushioning the effects of the impact. Providing the individual is aware of the depth of the water, the body is pre-programmed to respond appropriately. However, if an individual jumps into shallow water thinking it to be con- siderably deeper, then the correct adjustments are not made and injury may result.
There are an infinite number of postural sets relating to both the posture which an individual assumes and the preparatory adjustments made in advance of movement. For example, no one individual will consistently assume or maintain repeatable positions in standing. Equally, the means by which a person attains the standing position will vary according to the starting posi- tion and the reason for standing. For any given
task from a given position, postural adjustments are felt to be uniform but flexible to change with changing task (Hansen et al 1988, Horak et al
Key points of control are described as areas of the body from which movement may be most effect- ively controlled (Bobath 1990). Proximal key points are the trunk, head, shoulder girdles and pelvis and distal key points are the hands and feet. The choice of key point from which to influ- ence movement is determined by the ability of the individual to respond to facilitation of move- ment (Fig. 3.4A&B). For example, if the therapist facilitates movement using the patient's hand as a key point, there must be adequate postural tone within the trunk to make an appropriate response. If proximal control is lacking, attempts to bring the patient forwards from this key point may traumatise the shoulder joint. It is for this reason that the proximal key points tend to be utilised more frequently to ensure stability within the trunk prior to facilitating movement of the limbs.
The midline is an abstract reference point against which alignment of the aforementioned key points, particularly the trunk, shoulder girdles and pelvis, can be compared. It may be con- sidered a dividing line that serves as a point of reference for analysing body alignment and movement in either the sagittal, coronal or hori- zontal planes. Taylor et al (1994) describe the midline as an imaginary line that bisects the body into a right and left sector in the sagittal plane. This definition, which is limited to one plane, enables the physiotherapist to assess and describe body alignment in terms of lateral symmetry when observing the patient from in front or behind. The midline should also be considered as a point of reference in the coronal and transverse planes which provides a means of
Figure 3.4
(A) Proximal key point control. (B) Distal key point control.
describing the anteroposterior relationships of body structures and alignment with regard to rotation. The perception of body orientation in space depends on multisensory evaluation of visual, vestibular and proprioceptive sensory input (Karnath et al 1994). The concept of midline has physiological significance as it seems, at least for the upper limb, that some movements are pro- grammed to occur relative to the midline (Soechting & Flanders 1992).
lateral rotation in one leg than the other. This variability may ultimately prove to be irrelevant but one may question whether or not there is a reason for this discrepancy. The analysis of tonal influences in certain posi- tions may be based on observation of the rela- tionship between the trunk and the proximal key points and the limbs. This relationship may be used to enable the therapist to determine the overall influence of extension or flexion in each particular position.
It is useful to analyse positions because it pro- vides a baseline for determining differences which may arise due to pathology. It is important to recognise that very few normal subjects demonstrate the exact characteristics identified in this analysis. Many will show variability such as excessive flexion at the shoulders, an increased lumbar lordosis in supine or a greater degree of
An individual generally adopts a symmetrical position in relation to the supporting surface (Fig. 3.5). When lying supine, the influence of gravity and the reduction in the level of postural activity result in the shoulder girdles falling into retrac- tion. The ability to accept the base of support will vary considerably, depending upon the level of
Figure 3.5
Supine lying.
tonus and biomechanical properties of soft tissue structures. The upper limbs tend to adopt a position of lateral rotation with some abduction, the degree being determined by the individual's inherent level of postural tone. In general, the lower the tonus, the greater the degree of lateral rotation and abduction.
The pelvis tends to tilt posteriorly with increased extension at the hips. The extent of this pelvic movement is determined by the anatomi- cal structure of the individual, in particular the alignment of the pelvis with the lumbar spine
and the bulk of the gluteal region. The legs usually adopt a position of lateral rotation with some degree of abduction. This is a position of predominant extension; movement out of this position requires flexor activity, most commonly observed in conjunction with rotation.
The individual generally adopts a symmetrical position in relation to the supporting surface, but with the head turned laterally (Fig. 3.6).
Figure 3.6
Prone lying.
When prone, the shoulder girdles protract and the upper limbs rest in a position of flexion, medial rotation and adduction; the degree of adduction is determined by the amount of flexion. The pelvis tends to tilt anteriorly, producing a degree of flexion at the hips. The legs are extended, adducted and medially rotated and the feet plantar flexed. This is a position of predominant flexion. Movement out of this position requires extensor activity with a rotational component determined by the side to which the head is turned. As prone is a position with a predominant flexor influence, it is not necessarily the position of choice for management of those with flexor hypertonus. However, if the patient is able to accommodate to this position, it may be useful for preventing or correcting hip flexion contrac- tures. Standing, which has a greater influence of extension, may be more effective in managing this problem.
This is a position in which a degree of asymme- try between the two sides of the body is invari- ably present. Figure 3.7 illustrates one posture which may be adopted by an individual when asked to assume this position.
Certain characteristics may be noted. The weight-bearing side of the body is more extended and elongated than the non-weight-bearing side which is side flexed. This position is influenced by the anatomical structure of the individual; the greater the pelvic girth, the greater is the side flexion of the non-weight-bearing side.
There are many variations of the side-lying position. One such variation is bilateral flexion of the legs where the individual takes up a modi- fied foetal position. The position of the shoulder is determined by the tendency to lie towards prone or supine. Only those with bilateral leg flexion will lie with one side of the body virtually in alignment with the other. People who lie towards supine tend to protract the supporting shoulder, whereas those who lie towards prone tend to lie with the
supporting shoulder retracted. Accordingly, the degree of trunk rotation varies in respect of the position of the shoulders and their relationship with the pelvis. The weight-bearing side provides stability, through its acceptance of and interaction with the base of support, to allow for selective move- ment of the non-weight-bearing side. Impair- ment resulting in inactivity or inappropriate activity of the weight-bearing side may disrupt or prevent functional movement of the non- weight-bearing side. This is a position widely used and recom- mended in the positioning of patients with neu- rological disability (Bobath 1990, Davies 1994). The relative asymmetry of this position enables 'the break up' of either predominant flexor or extensor hypertonus. It is also recommended as a
position whereby coordination, postural control and sensory reintegration of the weight-bearing side may be facilitated through functional move- ment of the non-weight-bearing side.
Analysis of this position is complex due to the varying amount and type of support offered. This posture is described in terms of unsupported and supported sitting.
Unsupported sitting with 90 degrees
and knees at
Anti-gravity control in unsupported sitting (Fig. 3.8) is recruited primarily through extensor
activity at the pelvis and lumbar spine. In the absence of full support this anti-gravity, extensor activity is essential for dynamic maintenance of an upright posture. Consideration of the base of support in relation to the feet is discussed when analysing moving from sitting to standing. The shoulder girdles are protracted with medial rotation and adduction of the shoulders. This reflects the relative lack of activity required by the upper limbs to maintain this posture. The position of the pelvis depends upon the degree of upright or slumped sitting assumed by the individual. There is an element of extensor activity observed primarily at the lumbar spine and reflected in the degree of anterior pelvic tilt.
The degree of pelvic tilt influences the posi- tion of the lower limbs and vice versa. It is observed that the starting position affects associ- ated limb movements. With the hips and knees at 90 degrees or more flexion, the greater the anterior tilt, the more pronounced will be the degree of lateral rotation and abduction. How- ever, if the subject is seated on a higher chair with the hips and knees at an angle of less than 90 degrees, an increase in the anterior pelvic tilt tends to produce medial rotation and adduction. Conversely, if a patient has limited hip flexion, this is combined with posterior pelvic tilt and flexion of the lumbar spine.
Unsupported sitting is a position of predomi- nant flexion with recruitment of extensor activity arising primarily at the lumbar spine, pelvis and hips.
Supported sitting
The amount and type of support offered varies considerably between, for example, a dining chair and a lounge chair. The dining chair is a more rigid structure and therefore most individ- uals are less likely to relax and depend on it for full support. In many respects, the posture taken up by an individual sitting on a dining chair is no different from that of unsupported sitting.
Conversely, the lounge chair, depending upon the degree of comfort, the angle of recline and the provision or otherwise of a head support, affords more support to the individual (Fig. 3.9). The
body conforms to the chair with a posterior pelvic tilt and the shoulder girdles protracted. The arms and legs rest in various and diverse positions. Movement away from this position of full sup- port initially requires flexor activity closely fol- lowed by extension to provide the proximal stability essential for the achievement of function such as reaching for a cup or preparing to stand.
Supported sitting in a lounge chair is a posi- tion of predominant flexion, there being no necessity to recruit anti-gravity activity, given the extended base of support offered by the chair back and arms.
In contrast, the amount of activity when sitting on a dining chair depends upon the position of the pelvis: the degree of anterior or posterior tilt and whether it is forwards on the edge of the chair or positioned at the back of the chair.
The distribution of tone is also dependent on the extent of support. This support is substantially increased if the individual leans forward, resting the arms on a table such as when writing. In this posture there is a marked reduction in the anti- gravity activity within the trunk and pelvis. The size and distribution of the base of support are changed significantly with more weight being taken through the upper limbs, and hence the requirement for dynamic postural stability within the trunk and pelvis is reduced.
This analysis of sitting assists with the planning of treatment interventions. For example, for pa- tients with hypertonus, it may be more effective to provide an increased base of support in sitting to facilitate tone reduction. Conversely, for those with hypotonus, where the aim of treatment is to increase tone, less support should be provided by the therapist, thereby facilitating activity within the trunk. This analysis is also relevant to the provision of wheelchairs and the correct posi- tioning of the patient in the chair. The position of the pelvis will have a direct influence on the posture of the lower limbs. Equally, the use of upper limb support, such as a tray attached to a wheelchair, will have a direct effect on trunk and pelvic activity.
Standing requires extensive anti-gravity activity to sustain the upright position over a relatively small base of support. Muscle relaxation tends to accentuate the lumbar, thoracic and cervical curvatures and the pelvis tilts anteriorly. This posture may be seen in particularly lethargic individuals and in women in the later stages of pregnancy (Kapandji 1980).
Normal subjects may demonstrate flattening of spinal curvatures commensurate with their level of tonus (Fig. 3.10). This is initiated at the level of the pelvis. The anterior tilt of the pelvis is counterbalanced by the activity, primarily of gluteus maximus and the hamstrings, restoring the horizontal alignment of the interspinous line
It may be postulated that the position of the pelvis determines the extent of activity at the shoulder girdles and upper limbs. An anterior pelvic tilt introduces an element of flexion at the hips counteracted by increased extensor activity in the trunk, shoulder girdles and upper limbs. A neutral position of the pelvis or a slight posterior tilt produces a more mechanically efficient position as the iliofemoral ligament pro- vides anterior stability which complements the extensor activity at the hips and pelvis.
Activity within the foot musculature varies according to the size of the base of support. There is less activity in stride standing than when standing with a smaller base of support when the feet are closer together. The constant adjustments by the lower limbs and feet in response to any change in weight distribution serve to maintain the centre of gravity within the supporting surface. For this activity to be effective, adequate mobility within the feet and in the muscles acting over the ankle joint is essential.
In clinical practice it is observed that the major- ity of patients with abnormal tone affecting the feet lose some and, in severe cases, all of this mobility and as a result their balance in standing is impaired. Unless the problem of immobility of the feet is first addressed, rehabilitation of standing balance will be compromised.
between the anterior superior iliac spine and the posterior superior iliac spine. The abdominal muscles contract in conjunction with the gluteus maximus to flatten the lumbar curvature. From this position the paravertebral muscles can act effectively to pull back the upper lumbar verte- brae and extend the vertebral column (Kapandji
In standing, the upper limbs adopt a position of medial rotation with the shoulder girdles pro- tracted. Providing the centre of gravity remains within the base of support, the upper limbs are not essential for the maintenance of balance. This state of relative inactivity enables freedom of movement of the arms for the performance of functional tasks.
Although adults may be consistent in their per- formance, they have the ability to vary the movement patterns used in order to accomplish the task. It is this potential for variability that characterises normality (VanSant 1990a). Analysis of movement in clinical practice is based primarily on observation and knowledge of what is considered to be within normal limits. The movements of lying to sitting, sitting to standing and walking are discussed in a clinical perspective to identify certain features of these movement sequences. Although there will be sig- nificant variability in these movement sequences depending upon age, gender, body build, the height of the bed and the firmness of the sup-
porting surface, the characteristics described are those which may be considered to be within normal limits.
Initiation of movements from supine have been discussed in part in the previous analysis of the position of supine lying. The large base of support and low centre of mass demand significant effort on the part of the individual to move away from this position. The movement sequence will differ significantly between sitting up from lying on the floor and sitting up and placing the legs over the side of a bed. For relevance to treatment, it is the latter sequence which will be analysed. An assumption is made that the height of the bed is such that the individual can sit with the hips and knees at 90 degrees on completion of the move- ment and the surface of the bed is firm.
How is this movement from lying initiated? Bobath (1990) states that turning commences with the upper part of the body. It is observed that the majority of individuals flex forwards at the head and shoulders with varying degrees of rotation towards the side to which they are moving. However, others may initiate the movement with propulsion from the leg opposite to the side to which they are moving. Here the initial movement is one of flexion prior to pushing through the limb to generate the movement. The movement of the leg is then followed almost simultaneously by flexion of the head and trunk.
The fulcrum of movement is at the pelvis. As the individual brings the upper trunk forwards off the bed, the legs move towards the side of the bed. As the subject pivots over the pelvis to sit with the legs over the side of the bed, the weight-bearing side is elongated with contralateral side flexion of the opposite side of the trunk. During the course of the movement, the pelvis tends to be in a position of posterior tilt, but this will vary depending on the strength and control of the abdominals. Having attained this end position, the trunk is then realigned with more equal weight-bearing over the ischeal tuberosities with an anterior pelvic tilt.
To move from lying into sitting requires that the abdominal muscles move or hold the weight
of the
trunk against the pull of gravity and
control the speed at which it moves (Davies
1990). As with all movement, the speed at which
the sequence is carried out influences
ordination and degree of effort entailed. Young agile individuals will move more quickly and fluently than those of an older age group. The slower the speed at which the movement is carried out, the greater the effort required and
the greater the likelihood of dependence on the arms.
In clinical practice, impairment of this sequence of events is observed in a wide variety of cases. For example, in patients following surgery to the lumbar spine, pain inhibits movement and there is a loss of flexibility at the operation site. This disturbs the balance of activity and grading of movement within the trunk, most noticeably through the relative inactivity of the abdominals. Characteristically, these patients break up the movement sequence into specific components with an absence of rotation to minimise move- ment at the operation site. They first turn on to their side, often initiating the movement with one or both legs. They then move the legs over the side of the bed at virtually the same moment as they push up on their arms with little or no inter- play within the trunk and pelvis as described above. The psoas muscle seems to be more active, compensating for the inhibition of the abdomi- nals, in that the pelvis is held in a position of anterior tilt throughout the movement. A further illustration of the relationship between ab- dominal control and arm support is in people with a high thoracic cord lesion with paralysis of the abdominals. They are only able to attain the sitting position independently by means of a forced ballistic type movement of the upper limbs to initiate movement out of supine, and arm support to maintain themselves once in sitting.
Moving from sitting to standing
Standing from sitting is an activity which is per- formed frequently in daily life. In a review of the
(1991) categorised the
research relating to rising from a chair into four major areas:
• biomechanical investigations • kinematic studies • investigations of muscle activity • general studies of the functional aspects of seating for disabled people.
Many variables have been shown to influence getting up from a chair. These include the height of the chair, use of the arms, speed of movement, the direction of movement, placement of the feet and the age and sex of the individual. An example of the complexity of analysis of this movement sequence may be found in a study which demonstrated that in a sample of 10 young adults, five different arm patterns, three different head and trunk patterns and three different leg patterns were found to occur (Francis et al 1988 as cited by VanSant 1990b).
While producing definitive numerical data on moments of force generated at the joints and muscles of the lower extremity during rising, many of the biomechanical studies have demon- strated substantial complexity in study design, involving highly sophisticated technical equip- ment and considerable manipulation of subjects. This may preclude the application of such proce- dures to large samples of disabled subjects (Kerr et al 1991). The following analysis discusses the key components of sitting to standing and their significance to clinical practice.
The initial base of support is relatively large and includes the surface area of the chair with which the body is in contact, the floor area within the base of the chair and the area within and pos- terior to the foot position. A key component of this movement is the transference of weight from a relatively large base of support to one which is significantly smaller - the feet alone.
Many studies identify two distinct phases in moving from sitting into standing - initial for- ward trunk lean and upward extension (Nuzik et al 1986, Schenkman et al 1990).
On clinical observation, the movement for- wards of the trunk varies. In some individuals the trunk moves forwards on the pelvis prior to
the pelvis tilting anteriorly, whereas in others the trunk is held more rigidly extended and the trunk and pelvis move forwards simultaneously. This trunk and pelvic movement enables the weight to be transferred forwards over the feet. It may also be necessary for the individual to move the buttocks forwards, depending upon the initial position in the chair.
As the trunk and pelvis move forwards, the head extends and the knees move forwards over the feet so as to facilitate the transference of weight during upward extension. The knees move for- wards over the feet producing dorsiflexion at the ankle, the maximum range of dorsiflexion occur- ring as the buttocks are lifted from the seat of the chair. The legs extend as the individual moves into the upright position with a decreasing amount of activity in quadriceps as the knee angle approaches zero (Schuldt et al 1983). The anterior tilt of the pelvis is at its maximum as the buttocks are lifted off the chair and reduces as the sequence progresses, with extension of the hips on com- pletion of the movement. Similarly, the position of the head adjusts relative to the trunk throughout the sequence, moving from a more extended posi- tion at the beginning of the movement to one of relative flexion.
Many people with neurological disability have difficulty with this complex movement sequence. Treatment strategies vary depending on the dif- ferent reasons for the problem. Such problems may include restricted joint range at the foot and ankle or abnormal tone within the trunk and pelvis, both of which may preclude or impair the initial forward lean.
In clinical practice, the height of the chair or plinth is seen to be a critical factor in performance of the activity. Increasing seat height and the use of arms decreases muscle and joint forces at the hips and knees (Burdett et al 1985, Arborelius et al 1992) and also decreases energy expenditure (Didier et al 1993). Many patients benefit from first practising the movement from a higher seat and gradually reducing the height as they become more proficient.
The purpose of this analysis is to consider aspects of normal gait in relationship to patho- logical gait of neurological origin. Throughout this section the terms 'walking' and 'gait' are used interchangeably, although Whittle (1991) defines gait as the manner or style of walking rather than the walking process itself. There are many definitions of gait, which include:
a series of controlled falls (Rose et al 1982)
a method of locomotion involving the use of
the two legs, alternately, to provide both support and propulsion, at least one foot being in contact with the ground at all times (Whittle
a highly coordinated series of events in which balance is being constantly challenged and regained continuously (Galley & Forster 1987).
There are numerous studies which have described aspects of gait in detail. These include Saunders et al (1953), Murray et al (1964) and Whittle (1991). Saunders et al (1953) identified the primary determinants of human locomotion in respect of the behaviour of the centre of gravity of the body. In normal level walking, this follows a smooth, regular sinusoidal curve in the plane of progression which enables the human body to conserve energy.
Murray et al (1964) recorded the displacements associated with locomotion and established the ranges of normal values for many components of the walking cycle. These were considered in respect of the speed and timing of gait and stride dimensions, sagittal rotation of the pelvis, hip, knee and ankle and vertical, lateral and forward movement of the trunk and the transverse rotation of the pelvis and thorax.
The gait cycle
The gait cycle is the time interval between two successive occurrences of one of the repetitive events of walking (Whittle 1991). The cycle com- prises two component parts, the stance and swing phases. The stance phase is the portion of the cycle where the foot is in contact with the
floor and the swing phase is where the leg is off the ground moving forwards to take a step. There are two periods during the cycle when both feet are in contact with the ground. The pro- portion as a percentage of the walking cycle is 60% stance and 40% swing. The duration of the supportive phases of the walking cycle decreases with increased walking speeds (Smidt 1990).
Common characteristics of gait
Step and stride length. The step length is the distance between successive points of floor-to- floor contact of alternate feet; the stride length is the linear distance between successive points of floor-to-floor contact of the same foot. The step and stride length are related to the height of the individual, shorter subjects taking shorter steps and taller subjects longer steps, and to age, sub- jects over 60 having a shorter step length than those of a younger age group (Murray et al 1964, Prince et al 1997).
The stride width or walking base. This is the side-to-side distance between the line of the two feet, usually measured at the midpoint of the heel (Whittle 1991). It is directly related to the lateral displacement of the pelvis produced by the hori- zontal shift of the pelvis or relative adduction of the hip (Saunders et al 1953). This allows the stride width to remain within the pelvic circum- ference throughout the gait cycle, and Murray et al (1964) observed that the midpoint of one foot may even cross over the other. The stride width is not related to age or height nor does it correlate significantly with foot length, bi- acromial or bi-iliac measures (Murray et al 1964). Murray identified an increase in the foot angle (outward placement) of subjects over 60 years of age and suggested this to be their means of achieving additional lateral stability as the neuromuscular system begins to decline. The foot angle is also increased at slower walking speeds. An increase in the stride width is a notable feature in people with impaired balance. The degree to which it occurs depends on the extent of the damage to the CNS.
number of steps
velocity. The
given time and the
velocity of walking is the distance covered in a given time. The normal ranges for gait para- meters are given in Table 3.2. Greater velocities of locomotion are achieved by the lengthening of the stride rather than by an increase in cadence (Saunders et al 1953) and this depends to a great extent on the functional ob- jective. For example, strolling along the pro- menade is more leisurely than walking quickly knowing one is late for an appointment. Balance modification is directly related to speed; enforced reduction in the natural cadence will require increased postural adaptation.
The muscle activity required to step forwards differs in accordance with the speed of move- ment. For example, a step from a standing posi- tion requires greater hip flexor activity than a step taken as part of the gait cycle at the individ- ual's natural cadence. Similarly, the initiation of a step from a standing position produces a back- ward displacement of the body to counter the extended lever anteriorly, whereas the body is more upright in the natural gait cycle. These are important considerations for the physiotherapist when re-educating gait. In many instances, treat-
ment of necessity takes the form of re-education of the component parts, but it must be appre- ciated that fluidity and economy of movement are dependent upon the many factors associated with the gait cycle, not least cadence and speed. Re-education of gait at slow speeds often makes performance more difficult (Mauritz & Hesse
Rotation. The pelvis and thorax rotate simul- taneously in the transverse plane during each cycle of gait, the pelvis and shoulders rotating in opposite directions. Murray (1967) suggested that one of the functions of arm swing is to coun- teract excessive trunk rotation in the transverse plane. Maximum rotation occurs at the time of heel contact and the greater the speed, the greater the degree of rotation and subsequent arm swing. The enhanced amplitude of rotation is achieved mainly by increased shoulder extension on the backward end of the arm swing (Murray 1967). There is a decreased amplitude of rotation in the elderly which may be related to a more flexed posture (Elble et al 1991).
With increasing speed, either walking as quickly as possible or when running, the arm swing becomes more vigorous to help in both generating pace and in maintaining balance. An example is that of a sprinter in action. As the speed increases, so too does the pumping action of the arms combined with increased extension of the thoracic spine, perfectly illustrated as the athlete crosses the finishing line.
Disability resulting in an imbalance of the inter-reaction between flexor and extensor activ- ity may impair rotation. An example of this is illustrated in the person with Parkinson's disease (Rogers 1991). The main observable features are those of increased flexion and lack of rotation with the characteristic shuffling gait. In the past, therapists were taught to work for improved rotation by facilitating arm swing. Little attention was paid to the inherent loss of extensor activity. It is now widely accepted in clinical practice that rotation can only be facilitated on the basis of appropriate inter-reaction between flexion and extension within the trunk. Hence, in this instance, improving extension must occur before rotation is possible.
Vertical displacement. This occurs twice during the gait cycle and is approximately 50 mm (Whittle 1991). The summit of these oscillations occurs during the middle of stance phase and the centre of gravity falls to its lowest level during double stance when both feet are in contact with the ground (Saunders et al 1953). The magnitude of the vertical excursion correlates with the length of stride because when the step lengths are longer the lower limbs are more obliquely situated (Murray et al 1964). This characteristic ascent and descent of the body mass is altered in patients with hemiplegia. The movement is dependent upon sufficient muscle activity to maintain stabil- ity of the pelvis and hip joint during stance phase. Patients with hemiplegia often have inadequate or inappropriate activity to provide this stability. This gives rise to the characteristic unilateral Trendelenburg gait whereby the vertical dis- placement occurs only during stance phase of the unaffected leg (Wagenaar & Beek 1992).
activity and joint
Normal walking is dependent upon the continual interchange between mobility and stability (Perry 1992) with more than 1000 muscles moving over 200 bones around 100 movable joints (Prince et al 1997). Box 3.1 provides a summary of normal muscle activity and function during gait. These muscles do not have one single action but may work concentrically, eccentrically or isometrically at different stages of the gait cycle.
This is of particular relevance when con- sidering the use of muscle (botulinum toxin) or nerve (phenol) blocks. For example, the role of the plantar flexors is to contribute to knee stabil- ity, provide ankle stability, restrain the forward movement of the tibia on the talus during stance phase and minimise the vertical oscillation of the whole body centre of mass (Sutherland et al 1980). Therefore, while muscle or nerve blocks may reduce excessive or poorly timed calf muscle activation (Hesse et al 1994, Richardson et al 2000), they may also lead to knee and ankle instability and increased energy expenditure.
foot and ankle
Efficient transfer of weight from one leg to the other is partly dependent upon the ability of the feet to respond and adjust effectively to the base of support, be it a firm surface or over rough ground. The ankle and intrinsic foot musculature make constant adjustments to adapt appro- priately to provide the dynamic stability essen- tial for this acceptance of, and movement over, the base of support. The mobility of the foot and ankle is therefore essential for effective transfer of weight. The total range of dorsiflexion and plantar flexion varies between about 20 and 35 degrees, with foot clearance being only 0.87 cm in mid-swing (Gage 1992). Any restric- tion in this mobility will necessitate com- pensatory adjustments - for example, increased knee flexion or hip hitching. The muscle action occurring at the ankle is primarily that of dorsiflexion controlling the placing of the foot on the supporting surface fol- lowing heel strike and plantar flexion to propel the body forwards (Winter 1987, Kameyama et al
The knee
The range of movement at the knees is between approximately 70 degrees during the swing phase and full extension at the moment of heel strike and in mid-stance (Whittle 1991). In normal locomotion, the body moves forwards over the leg while the knee joint is flexed, the knee extending during stance and then once more flexing to carry the non-weight-bearing limb forwards. Saunders et al (1953) refer to the knee being locked in extension' during heel strike and during mid-stance but, on clinical observation, it would seem that this only occurs with pathology.
The hip
Movement at the hip is between approximately 30 degrees flexion and 20 degrees extension (Whittle 1991). The predominant activity during stance phase is that of extension and abduction as the
body moves forwards over the supporting foot. Prior to initiation of swing phase, the extended position at the hips is dependent upon the ability of the hip flexors to lengthen, thereby allowing this transference of weight. During swing phase, the primary activity is again that of extension acting as a deceleration force as the leg moves for- wards through momentum prior to heel strike (Whittle 1991). The leg initially flexes, with adduc-
tion and medial rotation at the hips. As the knee begins to extend in preparation for heel contact, the leg becomes more laterally rotated.
The pelvis
The pelvis provides the dynamic stability essen- tial for coordinating the activity of the lower limbs and the control and alignment of the trunk.
Many authors refer to rotation of the pelvis although it may be more appropriate, as the pelvis is a rigid structure, to consider rotation in relation to the hips and the thoracolumbar spine. Palpating the anterior superior iliac spines while walking at one's natural pace reveals little dis- cernible movement, the rotational movement being approximately 4 degrees on either side of the central axis, the lateral movement approxi- mately 5 degrees (Saunders et al 1953) and the anterior/posterior movement approximately 3 degrees (Murray et al 1964).
As the body moves forwards over the sup- porting leg, the pelvis maintains its stability predominantly through the action of gluteus maximus and medius. The maintenance of a neutral or slight posterior tilt of the pelvis is also determined by this activity.
Neural control
Control of locomotion is extremely complex. Leonard (1998) highlights this complexity in his analysis of human gait:
the CNS somehow must generate the locomotor pattern; generate appropriate propulsive forces; modulate changes in centre of gravity; coordinate multi-limb trajectories; adapt to changing conditions and changing joint positions; coordinate visual, auditory, vestibular and peripheral afferent information; and account for the viscoelastic properties of muscles. It must do all of this within milliseconds and usually in conjunction with coordinating a multitude of other bodily functions and movements.
Central pattern generators (CPGs) within the spinal cord generate the locomotor rhythm, but whereas cats with totally transected spinal cords still maintain the ability to walk, humans depend upon supraspinal control. It is suggested that descending systems integrate with spinal cord circuitry to fractionate lower limb movement and provide greater adaptability to changing afferent conditions (Dietz 1997, Leonard 1998).
For normal subjects, walking is goal-oriented and automatic with no consideration given to the component parts necessary to propel them on
their way. In contrast, many patients with neuro- logical impairment may have to consider every aspect of movement in walking. Conscious thought about how to put one foot forward in front of the other and maintain balance in order to achieve a functional goal is both physically and mentally demanding.
There are many assumptions within physio- therapy regarding the re-education of gait, the majority of which are unsubstantiated. Quality of movement is considered to be of the essence and yet, with a damaged nervous system, is it poss- ible to regain normal activity (Latash & Anson 1996)? There is widespread reluctance by physio- therapists to recommend the use of walking aids (Sackley & Lincoln 1996). However, Tyson (1999) found that these did not adversely affect walking ability and, although Hesse et al (1998) reported a more balanced walking pattern immediately following gait facilitation by Bobath therapists as opposed to walking with or without an aid, no carry-over could be demonstrated 1 hour after treatment. Hesse et al (1998) concluded that 'hesitant prescription' of walking aids for hemiplegic patients was not justified.
Significant improvements in gait have also been reported with the use of treadmill training with supported body weight. This means of gait training has been used for both incomplete spinal cord injured patients (Dobkin 1994, Dietz et al 1995) and for those with hemiplegia (Hesse et al 1995). For patients with spinal cord damage, it is suggested that this means of enhancing lower limb movement may prove useful in guiding and strengthening functional synapses of regenerating axons to maximise their contribution towards restoring function (Muir & Steeves 1997).
In summary, gait is an holistic motor goal of enormous complexity. There is only partial agreement between investigators as to what is the 'normal' pattern of muscle usage during gait (Whittle 1991). It is an automatic function whereby there is continual adaptation of postural tone in response to the constantly changing base of support. Any impairment, particularly of the
trunk, pelvis or lower limbs, may produce com- pensatory strategies, thereby disturbing the rhythm and economy of movement. However, Dietz (1997) suggests that the simpler regulation of muscle tension following spinal or supraspinal damage may be beneficial in that it enables the patient to support the body weight and achieve mobility. Although rapid movements are impaired due to the inability to modulate muscle activity, the altered regulation of 'spastic gait' may be considered as optimal for the given state of the motor system.
It is important that physiotherapists do not become too focused on using principles of their preferred treatment approaches to the detriment of others (Lennon 1996). For example, preventing patients with a pathological gait from walking until they have acquired a more normal pattern must be weighed against the advantages of early ambulation, namely to the musculoskeletal, cardiovascular, pulmonary and renal systems (Mauritz & Hesse 1996). Therapists must be aware of new developments and take these on board as possible treatment modalities in the functional re-education of gait.
Selective movement of the upper limb is depend- ent upon, not only normal neuromuscular innervation of the muscles of the arm but also the musculature of the shoulder girdle, trunk and legs. The shoulder is the most mobile joint of the body, being dependent pri- marily on muscle activity for its stability (Lippitt & Matsen 1993) and it is for this reason that it is so vulnerable to trauma. Following neuro- logical impairment, weakness, abnormal tone and impaired coordination of movement will have devastating effects on the glenohumeral joint.
In order to fully understand the functional problems which occur as a result of neurological impairment, it is first important to review the anatomy of the shoulder girdle. For this purpose, the shoulder mechanism is best considered in the context of thoracoscapular-humeral articulation. There are seven joints which provide this articulation (Fig. 3.11):
Figure 3.11 Composite drawing of the shoulder girdle (reproduced from Cailliet 1980 with kind permission). Key: 1 = glenohumeral; 2 = suprahumeral;
= acromioclavicular; 4 = scapulocostal;
= sternoclavicular; 6 = costosternal;
= costovertebral.
glenohumeral suprahumeral (a functional joint as opposed to
a true articulation) acromioclavicular
Relationship between shoulder girdle structures
Each joint is dependent on the others for the stability and control required in the performance of selective movement. The angular alignment of the glenoid fossa and its resultant position in relation to the head of humerus, provides a degree of stability described by Basmajian (1979) as 'the locking mechanism' of the shoulder. The positioning of the scapula is of importance in providing the degree of stability described by Basmajian. In normal subjects, if the arm is slightly abducted and then displaced down- wards, there is greater laxity at the glenohumeral joint than when this force is applied with the arm close in to the side of the body. Conversely, if the scapula rests in a more medially rotated position around the chest wall, this produces an increased
range of abduction at the glenohumeral joint with the potential for instability in the same way as that described above. Prevost et al (1987) dispute Basmajian's description of the scapula position in producing 'a locking mechanism'. In their study of 50 sub- jects following cerebrovascular accident (CVA), they found that there was a greater degree of downward facing of the glenoid fossa in the non-affected arm of these subjects than in the affected arm. They concluded that 'the glenoid fossa has a downward orientation in most normal shoulders and that Basmajian's generali- sation that the normal angle faces upward and the suggestion of a "locking mechanism" should be questioned'.
It may be hypothesised that following CVA the sound side becomes stronger to compensate for the impaired movement of the affected side. On observation, it seems that the greater the devel- opment of the shoulder girdle musculature, the greater the degree of medial rotation of the scapula.
Functional movement of the upper limb is also dependent upon thoracic joint motion. Increased thoracic mobility in younger subjects is related to a large range of arm elevation, whereas an increased kyphosis in older subjects is related to a reduced range of arm elevation (Crawford & Jull 1993). O'Gorman & Jull (1987) also revealed significant changes in the angle of kyphosis after the fifth decade and that the range of thoracic spine movement decreased with age. This rela- tionship between thoracic and glenohumeral movement is of significance when treating patients who are wheelchair dependent. The constant adoption of a flexed posture will con- sequently reduce extensor activity within the trunk.
When sitting or standing, anti-gravity muscle activity is recruited primarily in the trunk, pelvis and lower limbs; the shoulder girdles are relatively inactive in the maintenance of balance. This proximal stability is a prerequisite for upper limb function. Anticipatory pos- tural adjustments precede arm movements and appear to be pre-programmed (Friedli et al
Prehension/reaching and grasping
A prehensile act can be considered as two co- ordinated functional components that allow the hand eventually to establish the required contact with the object for manipulation to ensue. The transport component is responsible for bringing the hand /wrist system into the vicinity of the object to be grasped, and the grasp com- ponent is responsible for the formation of the grip (Bootsma et al 1994). The transport component is that of a high velocity, ballistic movement, involving primarily the proximal musculature of the shoulder and elbow to place the hand in the correct spatial location. The grasp component, the low-velocity phase, involves the musculature of the hand and forearm and serves to:
• orientate the hand and fingers to the structural characteristics of the object • ready the hand by forming an appropriate grasping shape • capture the object by closing the fingers about it (Marteniuk et al 1990).
These components occur at the same time and are thought to be independently programmed processes with visuomotor links (Jeannerod 1984). During visually guided movements, the CNS must convert information originating in visual brain regions into a pattern of muscle activity that moves the hand towards the target (Kalaska & Crammond 1992). Not only does vision direct placement of the arm during reach, it also influences the speed of the movement (Leonard 1998).
The theory of independence of the transport and grasp components is strengthened by the dif- ferent times at which they develop (Rosenbaum 1991, Gordon 1994), the fact that each can be solely affected by brain insult (Jeannerod 1994) and the different reaction times of the two com- ponents to a perturbation (Jeannerod et al 1991).
Inevitably the two components must be coor- dinated in some way in that the hand must open before contact with the object if prehension is to be achieved (Marteniuk et al 1990). This co- ordination is felt to be task specific, the exact temporal relationship between the two depend-
ing on the requirements of the task (Marteniuk et al 1990, van Vliet 1993, Wier 1994). The velocity of the transport component is asymmetrical, there being a sharp rise to its peak and then a less steep deceleration. There is a break point in the deceleration after approxi- mately 70-80% of the movement where the velocity becomes constant.
The grasp component occurs at the same time as the transport component. The grip size rapidly increases to a maximum aperture, the fingers then flex and the grip size decreases to match the size of the object. The finger grip opens wider than required so that the index finger can turn around the object to achieve the proper orienta- tion of the grip. The index finger seems to con- tribute most to the grip formation with the thumb position remaining constant (Jeannerod
influenced by many factors.
These include:
• vision
• proprioception (Jeannerod 1984, Gentilucci et al 1994) • touch (Wier 1994) • object properties relating to:
- substance: size and width (Jeannerod 1984,
Marteniuk et al 1987, Bootsma et al 1994)
- structure:
weight, texture and fragility
(Marteniuk et al 1987, Wier 1994) • function (van Vliet 1993, Ada et al 1994).
In the context of re-education of upper limb function it is important to take these factors into account. Retraining should be functional as information about the environment and the task appears to influence movement organisation (van Vliet 1993). The postural adjustments accompanying reaching and grasping, either in sitting (Moore et al 1992) or standing (Lee 1980, Friedli et al 1984, Horak et al 1984), must also be
addressed (Shepherd 1992). Brain-damaged patients may have difficulty eliciting any muscle activity in the early stages (Shepherd 1992, Ada et al 1994) or in controlling that activity in the presence of increased tone. Compensatory motor patterns may emerge as a result of several factors, which include:
the effects of the lesion
• the mechanical characteristics of the musculo- skeletal linkage • the environment in which the action is per- formed (Shepherd 1992).
These must be considered in respect of posi- tioning and appropriate treatment strategies to modify the demands placed upon the neuro- muscular system when attempting to re-educate prehension.
Analysis of 'normal movement' is recognised as an essential prerequisite for the assessment of patients with impairment of movement. It is this analysis that provides the basis for the problem- solving approach to treatment. Improved under- standing and awareness of movement enables the therapist to identify how a posture or move- ment differs from the normal and why an indi- vidual may have difficulty with functional skills.
It is inappropriate to imply that individuals must move or take up positions in a certain way to be considered normal. People with physical disability resent the implication that they are in some way abnormal merely because, through necessity, they use compensatory strategies and no longer function in the way they did before the onset of their disability.
Subsequent chapters will use this analysis in determining appropriate treatment strategies which may be adopted in the management of patients with neurological disability.
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General intellectual function
Neuropsychological tests of general intellectual
Clinical observations of general intellectual loss
Treatment strategies for patients with general
intellectual loss
Memory function
Neuropsychological tests of memory function
Clinical observations of memory dysfunction
Treatment strategies for patients with memory
Attention 75
Neurological tests of attention
Clinical observation of attentional deficits
Treatment strategies for patients with attentional
Language function
Neuropsychological tests of language 77 Clinical observation of language dysfunction 77 Treatment strategies for patients with language
Visual perception 78
Neuropsychological tests of visual perception 78 Clinical observations of visual perceptual
Treatment strategies for patients with visual
perceptual deficits
Spatial processing 78
Neuropsychological tests of spatial processing 78
Clinical observations of patients with spatial
Treatment strategies for patients with spatial
Praxis 80
Neuropsychological tests of praxis 80 Clinical observation of praxis 80
Treatment strategies for patients with apraxia 81
Executive functions 81
Neuropsychological tests of executive function
Clinical observation of dysexecutive syndrome
Treatment strategies for patients with dysexecutive
Neuropsychological tests of insight
Clinical observation of insight
Treatment strategies for patients with poor
Emotional distress
Neuropsychological tests of emotional
Clinical observation of emotional distress
Treatment strategies for emotionally distressed
Neuropsychological tests
Clinical observation
Treatment strategies
Wendy Langdon
Many neurological conditions involve the cere- bral hemispheres and thus have an impact on higher cortical function. A patient's cognitive function can have a great influence on the direc- tion, efficiency and success of a physiotherapy treatment. Sometimes this can be at a basic level, for example where a patient's memory dysfunc- tion or inability to initiate action means that she cannot present herself for treatment appoint- ments and hence the physiotherapist must escort her to and from the treatment area. On other occasions the influence of cognitive dysfunction might be at a more complex level, where, for example, a patient with multiple sclerosis (MS) who has the physical potential to walk is never- theless unsafe to do so, because of a marked dis- inhibition and impulsivity in his actions, and thus physiotherapy may target wheelchair tech- niques because they provide a safer form of mobility.
Research has shown that cognitive impairment can affect the outcome of therapy. Even in a fairly disabled group of MS patients undergoing inten- sive inpatient multidisciplinary therapy, their cognitive characteristics influenced how much independence they gained in everyday motor tasks (Langdon & Thompson 1999). However, functional independence can improve, even in the context of unchanging cognitive impairment (Langdon & Thompson 2000).
Neuropsychology attempts to understand the relationship between brain and behaviour. In a clinical setting, this means determining the pattern of neuropsychological impairment that a patient has suffered. The consequent cognitive
profile is then related to clinical observations of the patient's disability. Behaviours to be targeted in treatment are identified and agreed. A treat- ment programme is designed taking account of the patient's cognitive profile. Lastly, mechan- isms for evaluation of treatment and for making programme adjustments are put in place. Thus the approach does not differ substantially in structure from that of a physiotherapist except, understandably, cognitive function is considered in a more explicit and detailed manner and, cor- respondingly, physical aspects receive much less attention. These differences in emphasis and experience between the two disciplines make collaborative work essential with many neuro- logical patients.
Neuropsychologists have a wealth of validated measures and research findings to inform their clinical work. However, the purpose of this chapter is not to explore theoretical aspects in detail, and copious referencing has been avoided. Similarly, no consideration is given to diagnostic groups or anatomical correlates. There are many excellent neuropsychology texts that cover this ground (Obrzut 1986, Ellis & Young 1988, McCarthy & Warrington 1990).
Interested readers are advised to consult these authors for discussion of cognitive models of neuropsychological syndromes, anatomical con- siderations and for standard references. This chapter will focus on how acquired neuro- psychological deficits affect the function of adult neurological patients and ways in which these deficits can be identified and overcome in therapy. This is a less well researched area and is, therefore, approached from a clinical context.
The remainder of this chapter is arranged under 10 main headings: general intellectual function; memory function; attention; language function; visual perception; spatial processing; praxis; executive functions; insight; and emo- tional distress. These sections reflect the areas that might concern a neuropsychologist in the assessment and treatment of a patient. Each section is divided into three parts. First, one or two measures devised by neuropsychologists to delineate the deficit are described. This part aims to give a flavour of neuropsychological testing
and also a clearer impression of the impairment under consideration. Secondly, clinical observa- tions and therapeutic problems that typically relate to the cognitive deficit are described. With the assistance of a neuropsychologist, the clinical observations can be related to test findings and a clear profile of the patient's cognitive abilities may emerge. If you are relying on your own professional skill to determine cognitive impair- ment, then the part on clinical observation offers a brief description of how the cognitive deficit might manifest itself in therapy and pointers towards clinical assessment. Thirdly, some basic treatment strategies and options are discussed in relation to the cognitive deficit.
Admittedly, in most clinical practices it is rare to see patients with a single, or 'focal', cognitive deficit: however, this way of considering neuro- psychological dysfunction tends to be the clear- est. It is also the most convenient arrangement for those seeking to locate specific information relevant to a particular clinical problem.
Neuropsychological tests of general intellectual impairment
The most widely used test of individual general intellectual level is the Wechsler Adult Intelligence Scale - Revised (WAIS-III; Wechsler 1997). It comprises subtests, which are divided into verbal and performance subscales. The verbal subtests include:
• Information, which tests general knowledge • Comprehension, which examines common sense and social competence • Vocabulary, which requires the subject to define a graded list of words • Similarities, which asks the subject to say how pairs of words are alike • Arithmetic, a graded set of arithmetic problems • Digit Span, requiring the repetition of strings of digits either forwards or backwards.
The performance subtests utilise pictorial and spatial materials and include:
• Digit Symbol, a recoding task which requires the subject to write appropriate abstract symbols under printed numbers • Picture Completion, where the subject must indicate which important part is missing from each of 21 line drawings
Picture Arrangement, where small groups of drawings are laid on a desk in scrambled order and the subject must rearrange them to make a sensible story
assemble a complete two-dimensional object from the several flat fragments scattered before her on the desk.
The verbal subtest scores are summed as part of the calculation of the Verbal IQ and, similarly, the performance subtests are added together to obtain the Performance IQ. The Verbal, Performance and Full Scale IQs are derived by reference to normative data. As well as for the three IQs, age-referenced norms are also tabu- lated for each of the subtests. The classification
and distribution of IQ scores are given in Table
The WAIS-III gives a good indication of the patient's current level of intellectual function, a cognitive 'snapshot'. However, in order to detect intellectual deterioration, it is necessary to com- pare current function with how good a person's intellect has been in the past, which is termed their pre-morbid optimum. For some patients, their education or occupational history will
provide a pointer to their pre-morbid optimum, but this can at best only give a broad indication. A more precise estimate of pre-morbid intellect can be obtained from a patient's reading, for example on the National Adult Reading Test - Revised (NART-R; Nelson & Willison 1992). Reading scores are less affected in dementia than other cognitive skills (Nelson & McKenna 1975, Nelson & O'Connell 1978).
The NART-R consists of 50 printed words whose correct pronunciation is irregular, in the sense that the usual English spelling-to-sound rules do not apply. For example, a person who was to read the word 'debt' for the first time would probably sound the 'b' as part of the word and thus read it aloud incorrectly. However, people familiar with the word 'debt' pronounce it correctly. Their previous knowledge of the word allows them to pronounce it. Because all the words in the NART-R are similarly irregular, they are unlikely to be guessed correctly. Only words already in a patient's reading vocabulary will be accurately read aloud. By comparing a patient's current IQ with the NART-R, it is possi- ble to determine whether any significant loss of general intellectual function has occurred.
Tests of cognitive ability which were originally developed for general population use, such as the WAIS-III, often include task demands which can be inappropriate for neurological patients. For example, the Picture Arrangement subtest requires the patient to study between three and six cards, each of which carries a detailed line drawing (none greater than 5 cm square) and then to rearrange them so that they tell a story. Good manual dexterity and visual acuity are required, in addition to reasoning skills. Clearly, peripheral neurological dysfunction can handi- cap a patient on this subtest. If a patient with poor acuity and poor dexterity does badly, it is not clear whether peripheral deficits, cognitive deficits, or some mixture of both are to blame. The interpretation of the test results becomes problematic.
Many tests have been developed especially for neurological populations, although none have attained the dominance of the WAIS-III. An example of one designed to assess the general
intellectual level of neurological patients is the Verbal and Spatial Reasoning Test (VESPAR; Langdon & Warrington 1995). The VESPAR tests three types of inductive reasoning: categorisa- tion, analogy and series completion. The prob- lems are arranged in three matched sets of 25 verbal and 25 spatial items. The matched design allows fairly clear conclusions to be drawn if either verbal or spatial stimuli lead to poor performance, because the difference is unlikely to be due to different test procedures or task demands and most likely to be due to a spe- cific deficit in either verbal or spatial processing.
The stimuli were selected for their appro- priateness for neurological patients. The verbal items use common, or high-frequency, words which are less vulnerable to acquired language deficits. The spatial items are all clearly drawn and their solution does not depend on fine visual acuity or shape discrimination, faculties which may be compromised by neurological disease (Fig. 4.1). No manual dexterity is required of the patient. The forced choice format means that a variety of output modalities are possible. There are no penalties for slow performance. Thus the VESPAR attempts to minimise the effects of peripheral neurological deficits that may con- found patients' performance on traditional rea- soning tests, which attempt to measure central cognitive processes.
The clinical detection of a dementia can often be problematic, particularly in the early stages. This is especially true of Alzheimer's disease, where
Figure 4.1 Sample item from the verbal (A) and (B) spatial odd-one out sections of the VESPAR. (From Langdon D W, Warrington E K 1995 The VESPAR: a verbal and spatial reasoning test. Reprinted by permission of Lawrence Erlbaum Associates Ltd., Hove, UK.)
typically social skills are preserved and a casual conversation will not reveal anything amiss; or of MS, where typically language skills are unaffected and even an in-depth conversation will not reveal anything untoward. In general, patients who have suffered a widespread cognitive deterioration will find new information difficult to absorb and retain. They may require a great deal of prompting and repetition. Their powers of abstraction will be weakened and they will tend to see the world (and themselves) in rather concrete terms. This may result in their failing to bring problems to your attention or realise the implications of medical or treatment developments.
Their reduced cognitive capacity may have forced them to withdraw from established activ- ities, although patients may explain the change in terms of peripheral physical causes. For example, a patient whose reasoning powers fell to a level where they could no longer carry her through a knitting pattern, explained that she had given up knitting due to failing eyesight.
Treatment strategies for patients with general intellectual loss
A good recent summary of psychological treat- ment approaches to patients with dementia can be found in Holden & Woods (1995). In general, the poor abstracting abilities of these patients make it necessary for information to be provided in clear and concrete terms using short sentences and everyday words. For example a patient with a significant intellectual loss, who spends most of the day in a wheelchair and long periods immo- bile in bed, may not appreciate the need for a pressure care regime. The reasons why a pressure care regime will prevent pressure areas develop- ing may not be obvious to the patient. Similarly, the results of developing a pressure sore may need to be spelt out in graphic detail, because the logical outcome of failing to implement pressure care may well escape the patient. A written account in clear, concrete terms can pay divi- dends both as a prompt and as an aid to understanding.
This patient group requires as much structure as possible in their physiotherapy programme
and follow-up. They may need to be oriented at the start of each therapy session as to its purpose and content; to have their progress summarised at regular intervals; and to receive help, and perhaps explicit practice, in transferring tech- niques to new settings. If they have a home exer- cise programme, a diary or weekly chart to follow can be very helpful.
Memory function is the registration and retrieval of information of all kinds. A detailed review of the neuropsychology of memory in clinical prac- tice may be found in Kapur (1988). The basic principles of assessing memory function require a valid and systematic procedure in which a person remembers certain pieces of information in response to standard instructions. A memory test in widespread clinical use is the Recognition Memory Test (RMT; Warrington 1984). Fifty everyday words are presented to the patient at a rate of one every three seconds. The patient is required to say whether she likes each word, as a way of ensuring her attention. Next the patient is shown 50 pairs of everyday words. Each pair includes one word from the original single showing. The patient must say which of the two words she has just seen. A visual version, using photographs of male faces, follows the same procedure. The RMT is a relatively pure test of memory function, placing few demands on other cognitive skills. It was designed as a diagnostic test, to detect minor degrees of memory dys- function across a wide range of the adult population.
Wilson et al (1985) devised a test to evaluate everyday memory function. It includes a number of procedures:
• remembering a name associated with a face after 25 minutes • remembering to ask for an item and where it was hidden, after 25 minutes remembering to question the examiner after 20 minutes
recognising 10 pictures
recognising five faces
immediate and delayed recall of a story and a route.
There are four parallel forms, allowing change in patients' performance on the test to be moni- tored, unconfounded by the patient remember- ing stimuli from previous testing. The Rivermead Behavioural Memory Test samples a range of memory functions. It is a useful tool for both clinical screening and monitoring change.
A patient with memory dysfunction may fail to remember many kinds of information. Perhaps the most common demonstration in therapy is a failure to carry over techniques from a previous session, or to apply techniques to everyday life that have been rehearsed in therapy. However, a patient with a dense amnesic syndrome can exhibit far more extensive and disabling memory dys- function. For example, if a therapist leaves an amnesic patient for a few minutes to answer a tele- phone, the amnesic patient may well be bewil- dered when the therapist returns and ask who the therapist is. In the few minutes the therapist spent answering the telephone, all recall of the therapist, the therapy session and the location has vanished.
Discrepancies in different types of memory function can be observed. For example, a patient may have difficulty remembering words and other verbal material, but remain competent at remembering pictures and other visual material. This can be elucidated by discrepancies on the verbal and visual sections of the RMT (Warrington 1984), if a neuropsychological assessment is available. Otherwise, a simple test of telling the patient his appointment time (a verbal strategy) for one session and then showing him a picture of a clock set at the time of his appointment (a visual strategy) for the next session and observing the patient's attendance, might well indicate which memory system is the most efficient.
Apart from a general memory dysfunction for either verbal information or visual information, memory for certain types of verbal and visual information can be selectively impaired. For example, although a patient may be able to per- ceive an object efficiently (i.e. her visual percep- tual processes are intact), she may not be able to remember any knowledge about the object, for example its purpose. In the pure form, this impairment is termed visual agnosia. This syn- drome can have devastating results in everyday life, because patients may not be able to recog- nise a door handle or a toothbrush. In therapy, they may not be able to recognise a wheelchair brake and it will be hard for them to plan their movements in relation to objects if they are uncertain what they will operate or how to manipulate it.
Similarly, aspects of visual memory can be affected in isolation. Some patients can have a particular difficulty in recognising faces, a syn- drome termed prosopagnosia. Others may have a selective impairment in remembering routes within the hospital or around their home locality, which is termed topographical memory dys- function. Patients who cannot find their way around are clearly seriously disadvantaged when trying to improve their mobility.
As well as different types of memory being selectively impaired, different ways of remem- bering can be affected to varying degrees. For example, the RMT (Warrington 1984) requires patients to recognise words or faces that they have just seen and is thus a test of recognition memory. The test stimuli act as a prompt or a cue to help the patient remember. Patients remember far more words in this recognition format than they would if they were asked to recite all the words that they had just been shown, that is to recall the words without cue or prompt. For patients with memory dysfunction, the differ- ence between their ability to recall information unaided and their ability to remember informa- tion aided by a cue or a prompt can be very great.
As well as recall and recognition memory procedures, another format is paired-associate memory. Pairs of words are shown to the patient; then the first word of each pair is shown and the
patient is required to produce the second word that was its associate in the previously seen pair. The association can be strong (e.g. tea-cup) or so weak as to be simply that they were two un- related words that had been previously seen together (e.g. gate-carpet). The importance of this format is its apparent link to everyday memory function (Wilson et al 1985).
When assessing a patient's ability to remember information in therapy, it is important to be alert to how much prompting and cueing the patient is receiving. A patient may be able to recite perfectly the procedures for transferring safely from a wheelchair, in response to a series of questions, but that procedure assesses his prompted verbal memory function. The memory function required to perform transfers safely at home is recall performance memory, which could be assessed by observing the patient perform unprompted.
Treatment strategies for patients with memory dysfunction
A detailed account of neuropsychological treat- ments of memory dysfunction can be found in Wilson & Moffat (1984) and Wilson (1987). The first step to devising treatment strategies to overcome memory dysfunction is to assess the nature and extent of the patient's difficulties. If verbal memory function appears to be generally more efficient than visual memory function, then a written protocol for wheelc