Intraoperative and Long-Term Impedance Changes and Electrode Malfunctions in Cochlear Implant Recipients

Objective: This study aimed to investigate intraoperative and long-term impedance changes in cochlear implant recipients and to evaluate the prevalence and course of electrode circuit malfunctions. Methods: A retrospective longitudinal observational study was conducted on 358 ears that underwent cochlear implantation between October 2023 and June 2024. Intraoperative and postoperative impedance telemetry measurements were obtained at 1, 2, 6, and 12 months. Electrode arrays were analyzed according to their positions (basal, medial, apical), and electrode malfunctions were classified as open circuit (OC) or short circuit (SC). Results: Impedance values significantly increased from intraoperative to first activation measurements, reached their peak at the 1st postoperative month, and gradually decreased, stabilizing after the 6th month (p < 0.05). Electrode malfunctions were detected in 26 of 358 devices (7.2%), with 22 OCs (84.7%) and 4 SCs (15.3%). While 4 of the 22 OC cases improved within the first month after surgery, no improvement was observed in SC cases during the 12-month follow-up period. Conclusions: Impedance telemetry is useful for assessing electrode integrity intraoperatively and for monitoring changes over time during follow-up. These findings highlight the dynamic nature of impedance changes, particularly during the first 6 months, and underscore the value of regular follow-up measurements and individualized programming.