What is the impact of genetic diagnosis on postoperative hearing outcome with cochlear implant?

Background  Outcomes with cochlear implants (CI) show a large variability. The influence of known factors such as duration of deafness and residual hearing is about 20%. A genetic diagnosis could also have an influence on the CI outcome. The so-called "spiral ganglion hypothesis" suspects a relationship between the location of a gene expression in the cochlea (sensory vs. neuronal) and hearing outcome.

Material and Methods  For this study, a cohort of CI users (n=123 implanted ears; n=76 subjects) with a confirmed genetic aetiology of hearing loss according to the American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP) guidelines was identified and assessed for their postoperative audiological outcome. Results: In the 76 subjects, the genetic diagnosis included 35 genes and 61 relevant variants. Mutations in genes expressed in the spiral ganglion were found to be a significant factor negatively affecting cochlear implantation outcomes more than any other single clinical parameter.

Discussion  Analysis of the association between molecular genetic diagnosis of a hereditary aetiology of hearing loss and cochlear implantation outcomes demonstrated a significant influence. Expression in neuronal structures of the cochlea resulted in below-average speech understanding compared to expression in sensory parts. This supports the "spiral ganglion hypothesis".

Conclusion  Genetic diagnosis can contribute to the prognosis of postoperative hearing outcome in CI users and thus to preoperative counselling of patients.

Publication History

Article published online:
12 May 2023