Finger cold-induced vasodilatation, sympathetic skin response, and R-R interval variation in patients with progressive spinal muscular atrophy.

To elucidate autonomic function in spinal muscular atrophy, we evaluated finger cold-induced vasodilatation, sympathetic skin response, and R-R interval variation in 10 patients with spinal muscular atrophy: 7 of type 1, 2 of type 2, and 1 of type 3. Results of finger cold-induced vasodilatation, sympathetic skin response, and R-R interval variation were compared with those of healthy children. Finger cold-induced vasodilatation was abnormal in 6 of 10 patients with spinal muscular atrophy; it was normal in the healthy children. The mean sympathetic skin response latency and amplitude did not differ significantly from those of the healthy children. Amplitudes of sympathetic skin response to sound stimulation were absent or low in all six patients with spinal muscular atrophy. No significant difference was found in the mean R-R interval variation of patients with spinal muscular atrophy and healthy children. Results show that some patients with spinal muscular atrophy have autonomic dysfunction, especially sympathetic nerve hyperactivity, that resembles dysfunction observed in amyotrophic lateral sclerosis.