Auditory dysfunction in Friedreich ataxia: result of spiral ganglion degeneration

We performed behavioral audiometric tests and brainstem auditory evoked potentials in four patients with Friedreich ataxia. None of the patients had symptomatic hearing difficulties. Results of the audiometric tests pointed to a disorder of the eighth nerve. In none of the patients could we elicit normal-appearing waves of the brainstem auditory evoked potentials. These abnormalities could be attributed to degeneration of spiral ganglion neurons. Our patients had useful and functional hearing despite very abnormal brainstem auditory evoked potentials.