MicroRNA Profiling in the Perilymph of Cochlear Implant Patients: Identifying Markers that Correlate to Audiological Outcomes

Hypothesis MicroRNA (miRNA) expression profiles from human perilymph correlate to post cochlear implantation (CI) hearing outcomes. Background The high inter-individual variability in speech perception among cochlear implant recipients is still poorly understood. MiRNA expression in perilymph can be used to characterize the molecular processes underlying inner ear disease and to predict performance with a cochlear implant. Methods Perilymph collected during CI from 17 patients was analyzed using microarrays. MiRNAs were identified and multivariable analysis using consonant-nucleus-consonant testing at 6 and 18 months post implant activation was performed. Variables analyzed included age, gender, preoperative pure tone average (PTA), and preoperative speech discrimination (word recognition [WR]). Gene ontology analysis was performed to identify potential functional implications of changes in the identified miRNAs. Results Distinct miRNA profiles correlated to preoperative PTA and WR. Patients classified as poor performers showed downregulation of six miRNAs that potentially regulate pathways related to neuronal function and cell survival. Conclusion Individual miRNA profiles can be identified in microvolumes of perilymph. Distinct non-coding RNA expression profiles correlate to preoperative hearing and postoperative cochlear implant outcomes.