Genetic variants in the peripheral auditory system significantly affect adult cochlear implant performance

• Published in: Hearing research 2017-05, Vol.348, p.138-142
• Main Authors: Shearer, A. Eliot, Eppsteiner, Robert W., Frees, Kathy, Tejani, Viral, Sloan-Heggen, Christina M., Brown, Carolyn, Abbas, Paul, Dunn, Camille, Hansen, Marlan R., Gantz, Bruce J., Smith, Richard J.H.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Audiometry; Cochlea - surgery; Cochlear implant; Cochlear Implantation; Cochlear Implants; Deafness; Deafness - genetics; Deafness - surgery; Female; Genetic Variation; Genetics; Genomics; Hearing - physiology; Hearing Loss - surgery; Humans; Male; Membrane Proteins - genetics; Middle Aged; Models, Neurological; Neoplasm Proteins - genetics; Serine Endopeptidases - genetics; Speech Perception - physiology; Spiral Ganglion - physiology; Spiral Ganglion - surgery; Treatment Outcome
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2017.02.008

Cochlear implantation is an effective habilitation modality for adults with significant hearing loss. However, post-implant performance is variable. A portion of this variance in outcome can be attributed to clinical factors. Recent physiological studies suggest that the health of the spiral ganglion also impacts post-operative cochlear implant outcomes. The goal of this study was to determine whether genetic factors affecting spiral ganglion neurons may be associated with cochlear implant performance. Adults with post-lingual deafness who underwent cochlear implantation at the University of Iowa were studied. Pre-implantation evaluation included comprehensive genetic testing for genetic diagnosis. A novel score of genetic variants affecting genes with functional effects in the spiral ganglion was calculated. A Z-scored average of up to three post-operative speech perception tests (CNC, HINT, and AzBio) was used to assess outcome. Genetically determined spiral ganglion health affects cochlear implant outcomes, and when considered in conjunction with clinically determined etiology of deafness, accounts for 18.3% of the variance in postoperative speech recognition outcomes. Cochlear implant recipients with deleterious genetic variants that affect the cochlear sensory organ perform significantly better on tests of speech perception than recipients with deleterious genetic variants that affect the spiral ganglion. Etiological diagnosis of deafness including genetic testing is the single largest predictor of postoperative speech outcomes in adult cochlear implant recipients. A detailed understanding of the genetic underpinning of hearing loss will better inform pre-implant counseling. The method presented here should serve as a guide for further research into the molecular physiology of the peripheral auditory system and cochlear implants. •Cochlear implant (CI) outcomes are variable.•We hypothesize that the health of the neural component of the peripheral auditory system is an important factor in CI outcomes.•We show that adult CI users with deleterious mutations that affect the spiral ganglion perform significantly worse on speech recognition testing.•These results may guide pre-operative counseling for adult CI candidates.