Inherited myelopathies.

Inherited myelopathies are a small, but important subset of diseases that cause dysfunction of the spinal cord. Manifestations can include various combinations of signs and symptoms, including disturbance of gait, spasticity, paraplegia, amyotrophy, sensory loss, and urinary sphincter dysfunction. These diseases can be divided into classes that include (1) distal axonopathies-exemplified by hereditary spastic paraplegia, (2) motor neuron diseases including familial amyotrophic lateral sclerosis and spinal muscular atrophy, (3) inborn errors of metabolism such as adrenomyeloneuropathy, and (4) other inherited diseases with myelopathy as part of their spectrum of manifestations. Although the inherited myelopathies are relatively rare diseases, knowledge of them and their manifestations is important for the physician faced with a patient with myelopathy, particularly if there are similarly affected individuals in the patient's family. In addition, understanding the pathophysiologic underpinnings of these diseases provides insight into the molecular biology of the nervous system and provides a gateway toward developing treatments for these diseases.