Sympathetic iris function in amyotrophic lateral sclerosis.

Autonomic fibres are generally regarded as being spared in amyotrophic lateral sclerosis. Anatomical studies have cast some doubt upon this hypothesis. The present study describes the pupillary responses to tyramine, a norepinephrine releaser, and to phenylephrine, a directly acting sympathomimetic, in 11 patients with ALS and matched controls. Patients and controls showed a similar sensitivity to sympathomimetic agents, and our results lend some support to the hypothesis that sympathetic functions are not involved in ALS.