Cochlear implantation in patients with auditory neuropathy of varied etiologies.
OBJECTIVE
Auditory neuropathy is a relatively recently described pattern of hearing loss characterized by preservation of outer hair cell function despite absent brainstem auditory evoked responses. Intact outer hair cell function is demonstrated by the presence of otoacoustic emissions and/or a measurable cochlear microphonic on electrocochleography, whereas no synchronous neural activity (absent action potentials) is seen on acoustically evoked brainstem auditory evoked response testing. The study reviews the authors' experience with six patients diagnosed with auditory neuropathy, four of whom have undergone cochlear implantation.


METHODS
A retrospective review of all medical and audiological charts at the University of Virginia Hospitals (Charlottesville, VA) was performed to identify patients who have undergone cochlear implantation or have been diagnosed with auditory neuropathy, or both.


RESULTS
Six patients with hearing loss attributable to auditory neuropathy were identified, four of whom have undergone cochlear implantation. Causes varied, including congenital, infectious, and idiopathic origins. Adults demonstrated subjective auditory perception on promontory stimulation, whereas no repeatable brainstem auditory evoked response waveforms could be demonstrated on pediatric promontory stimulation testing. Patients with implants demonstrated implant-evoked brainstem auditory evoked responses and improved audiological performance.


CONCLUSIONS
The six cases presented in the study represent varied causes and, probably, varied sites of lesions of auditory neuropathy. Promontory stimulation has been valuable, particularly in adults. Cochlear implantation allows the opportunity to provide a supraphysiological electrical stimulation to the auditory nerve, with the hope of reintroducing synchronous neural activity. Greater confidence and enthusiasm for cochlear implantation in appropriately selected patients with auditory neuropathy are gained through experience with such diverse cases.
Mason
John C
JC
Department of Otolaryngology-Head and Neck Surgery, University of Virginia Hospitals, Charlottesville 22908-0713, USA. johnmason@virginia.edu
De Michele
Anne
A
Stevens
Christopher
C
Ruth
Roger A
RA
Hashisaki
George T
GT
D000328:Adult; D001300:Audiometry, Evoked Response; D001309:Auditory Threshold; D002675:Child, Preschool; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods*; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D005500:Follow-Up Studies; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D013067:Speech Perception; D016896:Treatment Outcome; D000160:Vestibulocochlear Nerve Diseases / Q000150:complications / Q000175:diagnosis / Q000601:surgery*