[Electrophysiological findings for 106 cases with auditory neuropathy].

Objective: To analyses the clinical characteristics and electrophysiological finding of 106 patients with auditory neuropathy (AN). Investigate the differential curve type of pure tone audiogram and the abnormal ABR.

Methods: Review the history of patients, pure tone audiometry, middle ear acoustic reflexes, auditory brainstem response, distortion product otoacoustic emission and radiologic imaging studies of the brain of 106 patients with AN during December 2001 to May 2007 in retrospect.

Results: The 106 patients with AN were of both genders. The age were between 11-37 years old, and the average age was 17.5 years old. The most patients were adolescence (70.8%). Twelve cases of the 106 patients had evidence of other peripheral neuropathy in addition to hearing loss. Another 94 patients were idiopathic origins. The pure tone audiogram showed a minimal to moderate sensorineural hearing loss at low frequencies 0.5 kHz and 0.25 kHz in 209 ears (98.6%). The average hearing threshold (WHO 1997) in 23.2% of disordered ears at less than 25 dB in the "normal" range. Auditory brainstem response could not be recorded in 124 ears (58.5%) at maximum stimulus. The other 88 ears showed 1 or 2 wave, but the wave were small. There were 23 patients which one side ear ABR was 1 or 2 small waves presented, but the contralateral side were all waves absent. In 3 cases of AN with other peripheral neuropathy which ABR were both ears 1 or 2 small wave ear recorded. However, 1 patient in our sample could not be detected distortion product otoacoustic emission at 3-6 kHz (left ear) and 5-6 kHz (right ear).

Conclusions: AN was not rare in adolescence. The average hearing threshold for AN should be discussed.