Cochlear implantation in otosclerosis: surgical and audiological outcomes between ossified and non-ossified cochlea.

Aim: To evaluate (1) Audiological and surgical outcomes in patients with otosclerosis following cochlear implantation. (2) surgical difficulties and outcomes between both groups. (3) Audiological outcomes between both groups.

Study design and setting: Retrospective study conducted at Otology and Skull Base Surgery Center.

Subjects and methods: Data were analyzed from 111 patients with otosclerosis (114 ears) who underwent cochlear implant surgery using the cochlear implant database. Demographic characteristics (age, sex, and operated ear), auditory outcomes, and operative details (extent of cochlear ossification, surgical approach [posterior tympanotomy or subtotal petrosectomy], electrode insertion [partial/complete, scala tympani or vestibuli], and complications) were analyzed Auditory outcomes were assessed over at least one year follow-up period using pure tone audiometry and speech discrimination scores. Patients were divided into two groups (with and without cochlear ossification) to compare auditory outcomes and surgical outcomes.

Results: The mean age of patients with ossified and non-ossified cochlea was 60.04 and 62.22 years respectively. Sixty-five of 114 ears had cochlear ossification, with complete round window involvement in 75.4% of these patients, while the rest had partial or complete basal turn ossification. Subtotal petrosectomy was performed in 63.1% and 28.6% of ossified and non-ossified cochlea respectively while the rest underwent cochlear implantation through posterior tympanotomy. Only one case had scala vestibuli insertion and four had incomplete electrode insertion. Six patients underwent re-implantation due to infection, device failure, and erosion of the posterior canal wall. Auditory outcomes among patients with ossified otosclerosis were slightly better than those without ossification but this difference was not statistically significant.

Conclusion: Cochlear implantation for otosclerosis yields excellent auditory outcomes with a low rate of surgical complications, despite the high incidence of cochlear ossification.