Spinal muscular atrophy in childhood. Two clues to clinical diagnosis.

A coarse tremor was noted in 13 children suffering from the childhood form of spinal muscular atrophy. Tremor has not been seen in any other condition producing proximal muscle weakness in childhood, and its presence should therefore suggest the diagnosis of spinal muscular atrophy. In addition, the feet of patients with spinal muscular atrophy tended to evert, whereas in Duchenne muscular dystrophy there was either no deformity or a tendency to toe walking.