Peripheral nerve disease.

Polyneuropathies are common neurologic disorders affecting the peripheral nerves. There are a number of causes of damage to these structures, such as genetic and metabolic factors, autoimmune disorders, infection, drug or environmental toxicity, and malignancy. Motor and sensory impairments are commonly encountered in these conditions, leading to altered balance and gait with increased risk of falling. Diabetic neuropathy is the most common cause of peripheral nerve disease and extensive investigation of balance and walking function revealed greater postural instability and delayed activation of distal muscles during walking. Although classically thought to be due to sensory impairment, it is now recognized that a motor contribution to balance and gait impairment cannot be ruled out in diabetic neuropathy. Inflammatory and inherited neuropathies have had less investigation. Variations in static and dynamic balance and depend on the sensory afferents affected and the degree of motor impairment. Motor impairment is a major contributor to alterations in gait pattern. Exercise is an effective rehabilitation approach that can improve muscle strength and postural responses. The gains can carry over into improved functional balance and walking. Orthotic interventions are also promising in supporting joints where there is significant muscle weakness, but newer devices are being developed that provide sensory feedback, e.g., vibration, which may be effective where sensory impairment is a key contributor to postural instability.