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International Journal of Otolaryngology
Volume 2012, Article ID 914986, 5 pages
http://dx.doi.org/10.1155/2012/914986
Clinical Study

Unilateral Auditory Neuropathy Caused by Cochlear Nerve Deficiency

1WHO Collaborating Centre for the Prevention of Deafness and Hearing Impairment, Nanjing Medical University, Nanjing 210029, China
2Department of Radiology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China
3Department of Otolaryngology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China

Received 19 July 2011; Revised 2 October 2011; Accepted 30 November 2011

Academic Editor: Robert K. Shepherd

Copyright © 2012 Cheng Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. To explore possible corelationship between the cochlear nerve deficiency (CND) and unilateral auditory neuropathy (AN). Methods. From a database of 85 patients with unilateral profound sensorineural hearing loss, eight who presented with evoked otoacoustic emissions (EOAEs) or cochlear microphonic (CM) in the affected ear were diagnosed with unilateral AN. Audiological and radiological records in eight patients with unilateral AN were retrospectively reviewed. Results. Eight cases were diagnosed as having unilateral AN caused by CND. Seven had type “A” tympanogram with normal EOAE in both ears. The other patient had unilateral type “B” tympanogram and absent OAE but CM recorded, consistent with middle ear effusion in the affected ear. For all the ears involved in the study, auditory brainstem responses (ABRs) were either absent or responded to the maximum output and the neural responses from the cochlea were not revealed when viewed by means of the oblique sagittal MRI on the internal auditory canal. Conclusion. Cochlear nerve deficiency can be seen by electrophysiological evidence and may be a significant cause of unilateral AN. Inclined sagittal MRI of the internal auditory canal is recommended for the diagnosis of this disorder.