[Auditory neuropathy: clinical presentation of seven cases and review of the literature]

Abstract

Introduction: Auditory Neuropathy (AN) is defined as a sensorineural hearing loss characterized by normal cochlear haircell function (assessed by recordable Otoacoustic Emissions) and absent or abnormal auditory brainstem evoked potentials (ABR) corroborated with absence of middle ear reflexes.

Patients and methods: We report five cases with AN. We also report two others cases in which the presentation was different but suggestive of AN. For the majority of patients, the hearing loss had been detected during childhood. Hearing assessment of these patients included appropriate behavioral audiometric techniques (Pure Tone Audiometry - PTA, and speech audiometry), objective measures of middle ear function, acoustic reflex studies, Otoacoustic Emissions (OAE) and Auditory Brainstem Responses (ABR).

Results: Pure tone audiometry revealed mild-to-profound hearing loss. In patients with recordable PTA thresholds were less degraded than speech intelligibility. In all patients, tympanogram and OtoAcoustic Emissions were normal. The stapedius reflex and Auditory Brainstem Responses were absent or very degraded.

Conclusions: AN can be diagnosed by the combined use of pure tone audiometry, speech audiometry, and objectives measures with the recording of OAE and ABR responses. Neonatal hearing loss OAE screening can miss babies with AN. The sooner the diagnosis is established the more successful the treatment, new opportunities being afforded by cochlear implantation.