Revision Cochlear Implantation With Different Electrodes Can Cause Incomplete Electrode Insertion and Poor Performance

Abstract

OBJECTIVES/HYPOTHESIS: To review our experiences with revision cochlear implantation (CI), to assess revision CI efficacy, and to find factors that cause incomplete electrode insertion. STUDY DESIGN: Retrospective chart review of revision CI from 2004 to 2011. SETTING: Academic tertiary referral center. PATIENTS: Twenty-two patients who underwent revision CI. INTERVENTIONS(S): Revision cochlear implant surgery, explanted device analysis, electrode analysis for a newly implanted device, measurement of electrode insertion depth on postoperative radiographic evaluation, and postoperative speech perception test by open-set testing. MAIN OUTCOME MEASURE(S): Surgical outcomes, postoperative performance, and analysis of used electrodes. RESULTS: Approximately 2.7% (22/816) of CI recipients underwent revision surgery. The reasons for revision surgery were device failure (n = 14) and medical reason (n = 8). Cochlear implantation was performed at an average of 4.7 years after initial operation. Seventeen patients underwent revision CI with an electrode that was the same as or similar to the initial one, and all electrodes were fully inserted. Different electrode types were used in the remaining 5 patients. Interestingly, 4 of the 5 had incomplete electrode insertion. Among the 4 patients, 2 had poorer open set sentence scores after revision than after initial surgery. CONCLUSION: In this study, full electrode insertion was achieved in all cases where the same type of electrode was used during initial and revision CI. In contrast, we noticed incomplete insertion in 4 of 5 patients who had revision electrodes that differed from initial electrodes. While incomplete electrode insertion does not necessitate poor speech performance, some patients with incomplete electrode insertion certainly experience it. Therefore, electrode selection requires circumspection in revision CI. Choosing a thinner electrode for revision CI may reduce the possibility of incomplete electrode insertion.