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An isolated and sporadic auditory neuropathy (auditory nerve disease): report of five patients

Published online by Cambridge University Press:  08 March 2006

Kianoush Sheykholeslami
Affiliation:
Department of Otolaryngology, University of Tokyo, Faculty of Medicine, Tokyo, Japan
Kimitaka Kaga
Affiliation:
Department of Otolaryngology, University of Tokyo, Faculty of Medicine, Tokyo, Japan
M. Kaga
Affiliation:
National Institute of Mental Health, National Center of Neurology and Psychiatry, Ichikawa, Japan

Abstract

Five patients of various ages with difficulty in speech discrimination were evaluated. All showed evidence of abnormal auditory brainstem responses (ABRs) beginning with the VIIIth cranial nerve. Broad summating potentials were evoked on their electrocochleograms (EcochGs) and they all exhibited almost normal cochlear outer hair cell function by otoacoustic emissions (OAEs) recordings. Behavioural audiometric testing revealed a mild to moderate elevation of pure-tone threshold in all patients. The shape of their pure-tone losses varied, being predominantly low-frequency in four patients (rising slope pattern) and flat across all frequencies in one patient. Speech intelligibility scores of all patients were poor and out of proportion to what would have been expected if threshold elevation of pure-tone was of cochlear origin (i.e. markedly poor scores on the speech audiogram with good scores on the auditory comprehension test). Patients were neurologically normal when the hearing impairment was first manifested. We suggest that this type of hearing impairment is due to an isolated and sporadic disorder of auditory nerve function. It occurs in isolation and does not seem to be part of a generalized neuropathological process.

Type
Research Article
Copyright
© Royal Society of Medicine Press Limited 2001

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