Abstract

Visual suppression of caloric nystagmus was studied in five patients with hereditary ataxia before and after administration of physostigmine. All patients had an initial abnormal ocular fixation index that improved after physostigmine was given. The data indicate that there is a partly reversible disturbance of visual-vestibular interaction in patients with hereditary ataxia, caused by an impairment of a central cholinergic mechanism.