Strength in toddlers is assessed by observing functional abilities, such as walking, stooping to pick up an object, and standing up from the floor. An older child should be able to easily reach high above his or her head, wheelbarrow walk, run, hop, go up and down stairs, and arise from the ground. Gower sign (child arises from lying on the floor by using his arms to climb up his legs and body) is a sign of significant proximal weakness. Subtle asymmetry can be detected when the child extends arms out in front with the palms upward and eyes closed. The hand on the weaker side cups and begins to pronate slowly (pronator drift). Cooperative children can undergo individual muscle strength testing. Muscle fasciculations indicate denervation from disease of the anterior horn cell or peripheral nerve.
Tone represents the dynamic resistance of muscles to passivestretch. Lower motor and cerebellar lesions produce decreasedtone (hypotonia). Upper motor lesions produce increased tone (spasticity). In extrapyramidal disease, an increase in resistanceis present throughout passive movement of a joint (rigidity).
Muscle bulk represents the volume of muscle tissue. In many lower motor neuron conditions (neuropathies, SMA), muscle bulk is diminished or atrophic. Excessive muscle bulk is seen in rare conditions, such as myotonia congenita; boys with Duchenne muscular dystrophy have pseudohypertrophy of their calves.
Ataxia is the lack of coordination of movement, which is typically due to a dysfunction of the cerebellar pathways. Observation and functional analysis help assess coordination in infants and toddlers. Watching the child sit or walk assesses truncal stability. Exchanging toys or objects with the child permits assessment of intention tremor and dysmetria (errors in judging distance), signs of cerebellar dysfunction. Cooperative children can do repetitive finger or foot tapping to test rapid alternating movements. Cerebellar and corticospinal tract dysfunction produce slowing and irregularity during tests of rapid alternating movements.
Watching a child creep, crawl, cruise, or walk is the best global assessment for the motor and coordination systems (Chapter 197). Subtle deficits and asymmetries in power, tone, or balance may be observed. The toddler gait is normally wide-based and unsteady. The base of the gait narrows with age. By 6 years, a child is able to walk on toes, walk on heels, and tandem walk (heel to toe). Cerebellar dysfunction results in a broad-based, unsteady gait accompanied by difficulty in executing turns. Corticospinal tract dysfunction produces a stiff, scissoring gait and toe walking. Arm swing is decreased, and the affected arm is flexed across the body. Extrapyramidal dysfunction produces a slow, stiff, shuffling gait with dystonic postures. A waddling gait occurs with hip weakness due to lower motor neuron or neuromuscular disorders. A steppage gait results from weakness of ankle dorsiflexors (common peroneal palsy).
Deep tendon reflexes can be elicited at any age and are reported on a 5-point scale: 2 Normal 3 Exaggerated reflex, with spread to contiguous areas quadriceps response) 4 Clonus (self-limited or sustained)These reflexes are decreased in lower motor neuron diseases and increased in upper motor neuron disease. Babinski response, or extensor plantar reflex, is an upward movement of the great toeand flaring of the toes on stimulation of the lateral foot and is asign of corticospinal tract dysfunction. This reflex is unreliablein neonates except when asymmetrical because the “normal”response at this age varies. By 12 to 18 months of age, the plantarresponse should consistently be flexor (toes flexing down).