The search for a physiologic marker of Machado-Joseph disease

Machado-Joseph disease is a dominantly inherited, multisystem, degenerative disorder that lacks a proven genetic marker. Peripheral nerve conduction-refractory period, sensory evoked potentials, and quantified oculomotor recordings were studied in nine patients affected with this disease to look for a potential physiologic marker. Only the oculomotor measurements of saccade and smooth pursuit gain were consistently abnormal in all patients. Identical eye movement recordings in 12 asymptomatic individuals at risk for Machado-Joseph disease revealed findings typical of affected patients in only 1 individual. Quantified oculomotor studies may contribute to the early confirmation of the disease, primarily in individuals at risk with minor or equivocal neurologic signs.