Neurophysiologic study of olivopontocerebellar atrophy with or without glutamate dehydrogenase deficiency

By neurophysiologic investigations, we evaluated 20 patients with olivopontocerebellar atrophy (OPCA), comprising 8 with glutamate dehydrogenase (GDH) deficiency and 12 with normal GDH activity. We found sensorimotor, predominantly sensory axonal neuropathy distally in the legs, and peripheral auditory nerve dysfunction (prolonged wave I but normal interpeak latencies in brainstem auditory evoked response) in GDH-deficient patients. These findings seem distinctive enough to serve as the electrophysiologic marker for diagnosis and monitoring of treatment and progression of the disease. The pattern-reversal visual and median nerve somatosensory evoked responses did not differ among the patients and controls.