Sympathetic Skin Response in Amyotrophic Lateral Sclerosis.

PURPOSE

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of motor neurons, but it is increasingly recognized to be a more disseminated disease. The literature on the involvement of the sympathetic skin response (SSR) in ALS is few.

METHODS

We reviewed the literature with specific emphasis on SSR in ALS and investigated SSR in 120 patients with sporadic ALS and in 130 age-matched healthy subjects to determine the effects of SSR in ALS patients. The SSR was conducted in all ALS patients and healthy subjects.

RESULTS

We found prolonged mean SSR latency in ALS patients, and the mean SSR amplitude is reduced compared with that of control subjects, especially in their low extremities (P < 0.05). The disease duration seems to have little impact on the SSR latency and amplitude (P > 0.05). Yet, whichever arm or leg involved, the overall difference in lower extremity SSR measurements between the two groups is significant (P < 0.05). And there is no correlation between initial manifestation of autonomic nervous impairment and amplitude and latency of SSR (P > 0.05).

CONCLUSIONS

The SSR impairment occurs mainly in lower extremities, which is earlier than clinical manifestation of autonomic nervous impairment in ALS. This may be a subclinical manifestation of ALS. We hypothesize that these results are caused by damage to the unmyelinated postganglionic fibers in ALS patients.