Electro-oculographic findings in Machado-Joseph disease.

Electro-oculographic recordings (EOG) were made on 26 patients with Machado-Joseph disease or at genetic risk for that disease. All patients with clinically apparent disease (ataxia, dysarthria, spasticity, or ophthalmoparesis) had abnormal eye movements. Defects in caloric response, sinusoidal tracking, opticokinetic nystagmus (OKN), refixation saccades, and presence of gaze paretic nystagmus were detected in that order of frequency. Fourteen subjects were clinically at risk but had normal neurologic examinations or minor equivocal signs. Nine of the fourteen had abnormal EOG, with sinusoidal tracking, calories, refixation saccades, OKN, and gaze paretic nystagmus being abnormal in that order. EOG may be useful in early case detection and may contribute to genetic counseling.