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Article J Influence of Visual Feedback Training on the Balance and Walking in Stroke

Korea Purpose: This study aimed to evaluate changes in the balance ability of patients whose head positions were altered due to stroke. Subjects were divided into three groups to determine the effects of the training on dynamic balance and gait. Methods: Forty-two stroke patients were enrolled. The Visual Feedback Training (VFT) group performed four sets of exercises per training session using a Sensoneck device, while the Active Range of Motion (ART) group performed eight sets per training session after receiving education from an experienced therapist. The Visual Feedback with Active Range of Motion (VAT) group performed four sets of active range of motion and two sets of visual-feedback training per session using a Sensoneck device. The training sessions were conducted three days a week for eight weeks. Results: The comparison of changes in dynamic balance ability showed that a significant difference in the total distance of the body center was found in the VFT group (p<0.05) and Significant differences were found according to the training period (p<0.05). The comparison of the 10 m walk test showed that the main effect test, treatment period and interactions between group had statistically significant differences between the three groups (p<0.05). Conclusion: Head-adjustment training using visual feedback can improve the balance ability and gait of stroke patients. These results show that coordination training between the eyes and head with visual feedback exercises can be used as a treatment approach to affect postural control through various activities involving the central nervous


INTRODUCTION
Patients with hemiplegia after stroke have balance-control problems, such as postural sway, asymmetrical weight support, damaged weight-transfer ability, and postural standing-control degradation.
Since most of their daily lives are spent sitting in wheelchairs during the early stages of rehabilitation, their exercise levels are very low compared to normal healthy individuals, and their selective trunk movements and balance abilities are significantly lower in the sitting position. 1 Some patients have asymmetrical posture of the head and neck due to the imbalance between muscle activity and stability and the changes in movement and stability between the head, trunk, and pelvis, as well as dominant use of the nonparetic side due to the lack of balance control, thereby inducing asymmetrical bodyweight support. 2 Therefore, balance on changing support-surfaces 3 during the rehabilitation of stroke patients and improvement of gait function, which is the most important factor in determining functional disability in stroke patients, are two of the most important goals during the rehabilitation process for all stroke patients. 4 To maintain balance effectively, it is necessary to combine the functions of the vestibular system, proprioceptors, and the visualinformation systems in the body. 5 In postural control, it is important to understand the ability to gaze at visual stimuli, one of the J KPT The Journal of Korean Physical Therapy termine the level of neuromuscular activity through anticipatory postural control when the body moves. 7 Stroke patients can lose visuospatial perception capability due to damaged function of the central nervous system, which integrates location sensory information received through visual information and proprioceptors. 8 The subjective visual vertical (SVV) is determined by the internal integration of the parietal-insular-vestibular cortex. Stroke patients who have damage in this region cannot properly align their bodies straight on unstable support surfaces. 9 The changed SVV causes changes in the head position of stroke patients 10 and the direction of SVV inclination is the same as that of body-trunk inclination in the standing position. 11 The inclination of SVV is related to the independence of stroke patients, 12 and inaccurate SVV creates balance and postural control problems. 13 A trajectory-tracking task, one of the visual-feedback training methods widely used in balance training after stroke, is used for patients who have damage to quantitative movement control, such as motor coordination during single-joint movements. 14 It is also used to investigate the effect of the damage to the central nervous system through accurate trajectory-tracking. 15 However, existing studies have focused only on balance or postural control training using the lower and upper extremities through virtual reality programs or Wii games on monitors.
This study conducted an experiment in which patients followed specific trajectories with their eyes using the Sensoneck device in the sitting position, tracking the trajectory with a laser-pointer flashlight attached to the head and aimed at a board in order to determine whether coordination ability was increased through head movements and eye-tracking and whether there was a correlation between the head/neck area and other body parts. It also aimed to determine the effect of changing postural alignment and the mobility of neuromuscular activities via neck exercises on the postural control of stroke patients by emphasizing motor-control therapy for coordination between the head and neck.

Study subjects
This study selected 42 patients, who understood the objective and participated voluntarily, from among stroke patients hospitalized at K Hospital in Daegu from March to April 2014. All subjects were diagnosed with stroke via computed tomography (CT) or magnetic resonance imaging (MRI), and their ages ranged from 16 to 65 years. Within three months after stroke onset, neurologic recovery progresses quickly so patients who were still in that period were excluded, while only patients with no severe cognitive or consciousness disorders and who could follow three-step commands were selected. Patients with visual problems, such as ophthalmodonesis or diplopia, or brainstem and cerebellar symptoms (vestibular dysfunction), were also excluded from the study, as were patients with receptive aphasia and hemi-neglect. All study subjects were fully informed about the study objectives and methods prior to the experiment, and voluntary consent was received from each participant. No significant differences in homogeneity and normality tests were found between the groups (p> 0.05) ( Table 1).

1) Measuring tools
The Sensoneck device of the TerapiMaster was used to train eyehead coordination. This device aims to test and exercise the neck A mean value was calculated after obtaining three measurements. 16 The three tasks were as follows: A. Walk upright with a straight head.
B. Walk while rotating the head from one side to the other.
C. Walk while lifting the head from the top to the bottom.
Each task was performed twice while walking, with a one-minute rest between tasks.

2) Measurement method
Prior to the experiment, the objectives and test methods of this study were explained to the 42 stroke patients who voluntarily con-

Statistics
The data acquired in this study were statistically processed using SPSS version 18.0. The general characteristics of the subjects were analyzed using one-way ANOVA, and two-way repeated ANOVA was used to compare differences between balance and walking abilities prior to the experiment, after four weeks, and after eight weeks for each group. For post-hoc comparison, least significant difference was calculated. The statistical significance level of α was set at p< 0.05.

1) Comparison of changes in total distance
Main effect tests showed no statistically significant differences between the three groups (p> 0.05) but between the training periods (prior to experiment, after four weeks, and after eight weeks) (p < 0.05). Furthermore, interactions between the groups and between the time before and after the experiment (prior to the experiment, after four weeks, and after eight weeks) showed no statistically significant differences (p> 0.05) ( Table 2).

2) Comparison of changes in M-L distance
Main effect tests showed statistically significant differences between the three groups (p < 0.05) and between the training periods (prior to experiment, after four weeks, and after eight weeks) (p < 0.05).
Furthermore, interactions between groups and between the time before and after the experiment (prior to the experiment, after four weeks, and after eight weeks) also showed statistically significant differences (p < 0.05) ( Table 3).

3) Comparison of changes in A-P distance
Main effect tests showed no statistically significant differences between the three groups (p> 0.05) but between the training periods (prior to experiment, after four weeks, and after eight weeks) (p < 0.05). Furthermore, interactions between groups and between the time before and after the experiment (prior to the experiment, after four weeks, and after eight weeks) showed no statistically significant differences (p> 0.05) ( Table 4).

Comparison of changes in 10 m walking speed between groups
Main effect tests showed statistically significant differences between the three groups (p < 0.05) and between the training periods (prior to experiment, after four weeks, and after eight weeks) (p < 0.05).
Furthermore, interactions between the groups and between the time before and after the experiment (prior to the experiment, after four weeks, and after eight weeks) also showed statistically signifi-    Thus, various activities through coordinated movements between the eyes and head can be one of the therapeutic approaches to affecting the postural control of stroke patients. If visual-feedback training such as trajectory tracking is applied to improve motor functions and balance-maintaining ability for stroke patients, their functional daily living performance will be improved.

DISCUSSION
The limitation of this study was that no measurement of saccade movements was conducted due to the focus on eye movements and the lack of studies on the effect of increased head coordination on coordination between the upper and lower extremities. In future studies, it will be necessary to investigate the effect of distal-portion activities, such as head movements, on the stability of the proximal portions of the body and the coordination of the extremities.