Spinal muscular atrophy

Rare condition involving decay of motor anterior horn cells in the spinal cord, causing slack paralysis. There are forms that occur particularly in children and which are probably hereditary; the more severe form rapidly causes invalidity, the more benign form only causes a certain degree of invalidity in later life. Spinal muscular atrophy in adults usually begins between the ages of 40 and 60; the cause is still unknown. The symptoms are increasing slack paralysis, leading to muscular atrophy. Irritation of the motor anterior horn cells causes small muscular contractions (fascicula-tion). The condition can be a component of amyotrophic lateral sclerosis; it can deteriorate gradually and is poten- tially fatal if respiratory difficulties set in. Diagnosis is by the characteristic clinical picture and electrical tests of muscles. There is no specific treatment.