DIFFICULT CASES OF COCHLEAR IMPLANTATION

Abstract

Background: In the recent years, there is a tendency to extend the indications to cochlear implantation in patients with inner and middle ear malformations, cochlea ossificans and Meniere's disease. In otosurgical practice, the cases are not uncommon when cochlear implantation is difficult after previous canal wall down mastoidectomy due to chronic suppurative otitis media. Aim: To improve postoperative auditory performance of patients with profound sensorineural hearing loss (deafness), complicated by the inner or middle ear disorders, through the optimization of cochlear implantation surgical technique. Materials and methods: We analyzed 42 patients with profound sensorineural hearing loss who underwent cochlear implantation, 12 of them having cochlea ossification after meningitis (group 1), 19, with inner ear malformations (group 2), 9, had underwent canal wall down mastoidectomy (group 3) and 2, with Meniere's disease (group 4). Surgical techniques varied depending on the type of disorder. In all patients, implant telemetry and evoked stapes reflex registration (if stapedium muscle was present) were performed. Postoperatively the mastoid cavity was controlled by otomicroscopy. Results: Stapes reflex were obtained in 8 patients from group 1. Number of from group 3 in whom of the proposed cochlear implantation technique was used, no long-term relapses of chronic suppurative otitis media were observed, the mastoid cavity could be visualized very well and graft survival was excellent. No cases of electrode array extrusion or protrusion were registered. Patients with Meniere's disease and bilateral sensorineural hearing loss who underwent simultaneous operations (endolymphatic sac drainage and cochlear implantation) showed satisfactory results of audioverbal rehabilitation and a marked reduction of vestibular symptoms. Conclusion: Surgical techniques proposed in this study allow for insertion of maximal electrode numbers into the spiral canal of a malformed and ossified cochlea. Formation of bone tunnels for the active electrode in the burred cavity and its covering with autocartilage helps to prevent any protrusion and displacement of the electrode in patients who had previously underwent canal wall down mastoidectomy. Simultaneous cochlear implantation and endolymphatic sac drainage is also considered to be an adequate approach to treatment of patients with late stage Meniere's disease with profound bilateral sensorineural hearing loss.