Slowing of voluntary and involuntary saccades: an early sign in spinocerebellar ataxia type 7.

We describe quantitative oculomotor findings in a patient with subclinical spinocerebellar ataxia type 7 (SCA7) and a borderline mutation of 38 CAG repeats and her daughter with SCA7 and 46 repeats. Both subjects demonstrated significant slowing of voluntary and involuntary saccades, but retinal examination was normal. Smooth pursuit and fixation suppression of VOR were mildly impaired. Slow saccades may be the earliest neurologic finding even in asymptomatic SCA7 patients with normal ocular fundi. The SCA7 mutation probably has an early impact on brainstem fast eye movement centers.