Cochlear Implantation in Cochlear Ossification: Retrospective Review of Etiologies, Surgical Considerations, and Auditory Outcomes.

OBJECTIVES

1. To review the surgical and auditory outcomes and complications of cochlear implantation in cases with cochlear ossification. 2) To evaluate association between the extent and etiology of ossification to outcomes.

STUDY DESIGN

Retrospective study.

SETTING

Otology and skull base surgery center.

SUBJECTS AND METHODS

Charts of 40 patients (42 ears) with cochlear ossification undergoing cochlear implantation were reviewed. Demographic features, operative findings, auditory outcomes, and complications were analyzed. Operative findings included extent of cochlear ossification, extent of drilling required to obtain patent cochlear lumen, approach (posterior tympanotomy/subtotal petrosectomy), electrode insertion (partial/complete, scala tympani/vestibuli), and complications. Auditory outcomes were assessed over a 4-year follow-up period using vowel, word, sentence, and comprehension scores. Patients were divided into groups (otosclerotic/non-otosclerotic and round window/basal turn ossification) for comparison of auditory outcomes. Outcomes were compared with 60 randomly identified controls (adults with postlingual deafness) who underwent implantation with no cochlear ossification.

RESULTS

The median age and duration of deafness of patients was 54.39 and 27.15 years, respectively. Etiology of cochlear ossification was otosclerosis in 23 of 42 ears and mixed in 19 of 42 ears (chronic otitis media, temporal bone fractures, idiopathic, meningitis, Cogan's syndrome) with exclusive round window involvement in 54.7% of cases and the rest having partial or complete basal turn ossification. 59.5% ears underwent subtotal petrosectomy for implantation. Three patients underwent scala vestibuli insertion and five had incomplete electrode insertion. Auditory outcomes were comparable in otosclerotic and non-otosclerotic cases and in round window and basal turn ossification cases. No significant differences were observed in auditory scores when compared with controls with no ossification.

CONCLUSIONS

Cochlear implantation in cochlear ossification is feasible despite surgical challenges and modifications. Auditory outcomes in basal turn ossification appear to be comparable to cases with no ossification with extent of ossification having no significant association with outcomes.