Inner ear malformations in cochlear implant recipients

Objective: The aim of this study is to determine the prevalence of the inner ear malformations (IEMs) in cochlear implant recipients according to Sennaroglu's classification, and to document the intraoperative difficulties and complications in those cases. Methods: This was a descriptive cross-sectional study performed at our hospital between January 2016 and October 2019. IEMs on temporal bone computed tomography scans were identified in all patients who received cochlear implants during the study. Intraoperative difficulties and complications relating to these malformations were described. Results: Twelve patients with IEMs were identified from a total of 212 cochlear implant recipients, representing a prevalence of 5.7%. Among them, one patient with incomplete partition (IP) Type I (8.3%), seven patients with IP Type II (58.3%), one patient with IP Type III (8.3%), one patient with cochlear hypoplasia (CH) Type I (8.3%), and two patients with CH Type III (16.7%) were identified. Associated enlarged vestibular aqueduct was found in four cases with IP Type II (33.3%). Round windows were not identified intraoperatively in 3 cases with CH (25%). Three cases (25%) had cerebrospinal fluid gusher (one patient in each of the following anomalies: IP-I, IP-II, and IP-III). The mean categories of auditory performance score was 6, which was collected within 23.3 months after the surgery. Conclusion: This study documents the prevalence of IEMs in cochlear implant recipients (classified by Sennaroglu in 2017). The identification of such anomalies will significantly aid surgeons in making decisions regarding cochlear implant candidacy and surgical strategy when cochlear implantation is contemplated to obtain optimal outcomes.