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Prediction of cochlear implant performance by genetic mutation: the spiral ganglion hypothesis
Journal article   Peer reviewed

Prediction of cochlear implant performance by genetic mutation: the spiral ganglion hypothesis

Robert W Eppsteiner, A Eliot Shearer, Michael S Hildebrand, Adam P Deluca, Haihong Ji, Camille C Dunn, Elizabeth A Black-Ziegelbein, Thomas L Casavant, Terry A Braun, Todd E Scheetz, …
Hearing research, Vol.292(1-2), pp.51-58
10/2012
DOI: 10.1016/j.heares.2012.08.007
PMCID: PMC3461332
PMID: 22975204

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Abstract

Up to 7% of patients with severe-to-profound deafness do not benefit from cochlear implantation. Given the high surgical implantation and clinical management cost of cochlear implantation (>$1 million lifetime cost), prospective identification of the worst performers would reduce unnecessary procedures and healthcare costs. Because cochlear implants bypass the membranous labyrinth but rely on the spiral ganglion for functionality, we hypothesize that cochlear implant (CI) performance is dictated in part by the anatomic location of the cochlear pathology that underlies the hearing loss. As a corollary, we hypothesize that because genetic testing can identify sites of cochlear pathology, it may be useful in predicting CI performance. 29 adult CI recipients with idiopathic adult-onset severe-to-profound hearing loss were studied. DNA samples were subjected to solution-based sequence capture and massively parallel sequencing using the OtoSCOPE(®) platform. The cohort was divided into three CI performance groups (good, intermediate, poor) and genetic causes of deafness were correlated with audiometric data to determine whether there was a gene-specific impact on CI performance. The genetic cause of deafness was determined in 3/29 (10%) individuals. The two poor performers segregated mutations in TMPRSS3, a gene expressed in the spiral ganglion, while the good performer segregated mutations in LOXHD1, a gene expressed in the membranous labyrinth. Comprehensive literature review identified other good performers with mutations in membranous labyrinth-expressed genes; poor performance was associated with spiral ganglion-expressed genes. Our data support the underlying hypothesis that mutations in genes preferentially expressed in the spiral ganglion portend poor CI performance while mutations in genes expressed in the membranous labyrinth portend good CI performance. Although the low mutation rate in known deafness genes in this cohort likely relates to the ascertainment characteristics (postlingual hearing loss in adult CI recipients), these data suggest that genetic testing should be implemented as part of the CI evaluation to test this association prospectively.
Hearing Loss - diagnosis Humans Middle Aged Correction of Hearing Impairment Male Patient Selection DNA Mutational Analysis Serine Endopeptidases - genetics Spiral Ganglion - pathology Cochlear Implantation - instrumentation Hearing Loss - rehabilitation Adult Female Neoplasm Proteins - genetics Severity of Illness Index Genetic Predisposition to Disease Hearing Loss - physiopathology Acoustic Stimulation Membrane Proteins - genetics Gene Expression Regulation Persons With Hearing Impairments - rehabilitation Hearing Loss - pathology Chi-Square Distribution Auditory Threshold Hearing Loss - genetics Carrier Proteins - genetics Phenotype Analysis of Variance Audiometry, Pure-Tone Aged Cochlear Implants Mutation Spiral Ganglion - physiopathology

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