Audiological characteristics of patients with auditory neuropathy

Objective To explore the audiological characteristics of the auditory neuropathy. Methods Pure tone audiometry, acoustic stapedial reflex, speech audiometry, auditory brainstem response(ABR), electrocochleogram(ECochG) as well as distortion product otoacoustic emission(DPOAE) and the contralateral suppression of white noise were administered to 22 patients with auditory neuropathy. Ten patients were investigated with brain magnetic resonance imaging(MRI). Results Out of 22 cases, 13 female and 9 male complainted of bilateral hearing loss. The onset of the disorder was from 10 to 20 years old. Seven patients had a tinnitus of both ears. The pure tone audiogram showed mild or moderate sensorineural hearing loss. Stapedial reflex was absent in 22 patients. ABR was absent or severely abnormal in 22 cases. All of the patients had responses through DPOAE test and no suppression was achieved by contralateral white noise. ECochG demonstrated -SP/AP0.4 in 17 cases, and 5 patients? action potential(AP) amplitude was very low. The findings of MRI were normal. Conclusion Patients with auditory neuropathy were predominantly young at age. Pure tone audiometry showed mainly bilateral mild to moderate hearing loss at low frequencies, but their stapedial reflexes and ABR were absent. DPOAE was normal. The precise pathologic site of the disease is yet to be defined. The clinical auditory characteristics of auditory neuropathy are very important for diagnosing this disorder.