Sympathetic skin response in patients with amyotrophic lateral sclerosis

To determine a possible involvement of the autonomic nervous system in amyotrophic lateral sclerosis (ALS), measurement of the sympathetic skin response (SSR) was performed in 15 patients with definite ALS. Findings were compared with those in 20 normal controls. In ALS patients the mean SSR latencies recorded from the palms and soles were both significantly prolonged (p < 0.05) and the amplitudes were reduced as compared with normal persons. In 5 patients, SSR potentials were completely lacking in one or even more extremities. Our data strongly suggest subclinical involvement of the autonomic nervous system in ALS as assessed by the SSR response. In our patients the extent of autonomic dysfunction was not related to the stage or the duration of disease.