Brainstem auditory evoked responses in hereditary spinocerebellar ataxias.

Brainstem auditory evoked responses were recorded in 18 patients with spinocerebellar ataxia, seven with Friedreich's ataxia, four with late-onset cerebellar degeneration, and seven with olivopontocerebellar atrophy. All patients had normal hearing. BAERs were abnormal in 10 cases (58%). Five of the seven patients with Friedreich's ataxia (71%) had grossly abnormal BAERs with wave I only being identified. Five of the patients with olivopontocerebellar atrophy (71%) had abnormal BAERs, whereas all patients with cerebellar degeneration had normal BAERs. The results indicate abnormalities of the brainstem auditory pathways in patients with spinocerebellar ataxias and show that the test is of value in the differential diagnosis of this group of disorders.