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Psychophysical evaluation of cochlear hair cell damage due to the A3243G mitochondrial DNA mutation

Lookup NU author(s): Professor Tim GriffithsORCiD, Chris Elliott, Professor Patrick Chinnery


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Mitochondrial dysfunction is an important cause of human deafness, implicated in genetic deafness, toxin and noise damage. We assessed the mechanism of cochlear dysfunction in a population of 11 subjects with a specific mitochondrial disorder caused by the A3243G mitochondrial DNA mutation. Psychophysical tests were carried out to assess the inner and outer hair cell functions in vivo. Inner hair cell function was assessed using a measure of hearing threshold in the presence of "threshold-equalizing noise" which can indicate "dead regions" where the transduction mechanism fails. Outer hair cell function was assessed by using the notched-noise method to measure auditory filter width, dependent on active mechanisms in the outer hair cell. The results support the conclusion that this mitochondrial disorder causes both inner and outer hair cell dysfunctions. Evidence of inner hair cell dysfunction was found mainly in basal (high frequency) regions of the cochlea and occurred even in some subjects with only mild hearing loss. Evidence of outer hair cell dysfunction was found in some instances where pure tone threshold was at or close to normal. The common occurrence of dead regions in the basal cochlea has treatment implication for this form of deafness; such people may not be helped by amplification of high frequencies.

Publication metadata

Author(s): Chinnery PF; Griffiths TD; Elliott C; Blakemore S; Moore BCJ

Publication type: Article

Publication status: Published

Journal: JARO - Journal of the Association for Research in Otolaryngology

Year: 2001

Volume: 2

Issue: 2

Pages: 172-179

Print publication date: 01/01/2001

ISSN (print): 1525-3961

ISSN (electronic): 1438-7573

Publisher: Springer New York LLC


DOI: 10.1007/s101620010061

PubMed id: 11550526


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