Performance Results and Timing of Cochlear Implantation in Patients With DFNA9 (p.Pro51Ser).

Abstract

Objective: To evaluate long-term outcomes of cochlear implantation (CI) in DFNA9 patients with the p.Pro51Ser COCH variant, compared with matched controls, and to identify clinical predictors of performance and quality of life (QoL).

Background: DFNA9, caused by pathogenic variants in the COCH gene, is a progressive hereditary hearing loss with variable vestibular dysfunction that often necessitates cochlear implantation.

Methods: In this retrospective cohort study, 56 DFNA9 patients were compared with case-matched postlingually deaf CI recipients without hereditary hearing loss. Speech perception, pure-tone thresholds, and QoL (Nijmegen Cochlear Implant Questionnaire, Glasgow Benefit Inventory) were assessed preimplantation and at 6 weeks, 1 year, and 5 years. Linear and mixed-effects models were applied to identify predictors and longitudinal changes.

Results: Cochlear implantation significantly improved speech perception and QoL in both groups, with no differences between DFNA9 and controls and stable performance up to 5 years. Postoperative residual hearing (PTA₀.₅-2 kHz) was a significant predictor of 1-year speech perception. In DFNA9, higher preoperative aided speech perception was more strongly associated with postoperative outcomes, underscoring the advantage of implantation before further decline. Speech perception scores predicted QoL, although the link with perceived social benefit was weaker in DFNA9 than in controls.

Conclusions: CI provides durable, noninferior outcomes in DFNA9 patients compared with controls. Although the study did not examine the impact of hearing loss severity or rate of decline, the excellent outcomes observed in this cohort may help clinicians to consider earlier implantation.