Hereditary distal spinal muscular atrophy. A report on 34 cases and a review of the literature.

A description is given of 34 patients with the distal form of hereditary spinal muscular atrophy. This disorder constitutes one form of "peroneal muscular atrophy". It resembles types I and II hereditary motor and sensory neuropathy but differs from them in displaying less upper limb weakness, relative preservation of the tendon reflexes and an entirely normal clinical sensory examination. Motor nerve conduction velocity and sensory nerve action potentials are normal. Previous reports of this disorder are reviewed and compared with the present series.