Electrode Choices in Cochlear Incomplete Partition Type III: The Experience of a Romanian Tertiary Unit

Objectives: Incomplete partition type III is a rare malformation of the inner ear characterized by the absence of the modiolus, fixation of the stapes, and significant communication between the cochlea and the internal auditory canal (IAC). During cochlear implant (CI) surgery, there is a risk that the electrode array may enter the IAC, resulting in non-specific stimulation of auditory neurons or other nerve fibers inside the IAC. In this study, we present our experience with CI surgery in patients with incomplete partition type III and report the types of devices utilized. Methods: A retrospective analysis was conducted on all our patients with cochlear incomplete partition type III who underwent surgical cochlear implantation in a tertiary referral unit over the past 16 years. Results: Of the perimodiolar electrodes used initially, four were correctly positioned within the cochlea from initial insertion, and no reinsertion was necessary. A lateral wall electrode array CI was selected to replace the last failed perimodiolar insertion, but it also required two insertion attempts due to its initial misplacement into the internal auditory canal. Conclusions: In this study, electrode array selection was influenced by surgeon preference and by intraoperative factors such as the severity of the gusher. Our observations suggest that perimodiolar CIs can be used in selected cases of incomplete partition type III and did not appear to increase the risk of IAC misplacement compared with the lateral wall array used in one patient. However, these findings should be interpreted cautiously as observations from the authors' experience rather than as generalized conclusions regarding the relative safety of perimodiolar versus lateral wall electrode arrays. Lateral wall arrays may also be misplaced into the IAC, and their use may be considered in cases with severe and difficult-to-control gusher.