Patient Directed Basal Electrode Deactivation Is Associated with Diminished Audibility

Introduction: Cochlear implantation (CI) has revolutionized patient care, however speech and audibility outcomes vary between recipients. This study evaluates post-operative CI performance in recipients with an intact electrode array compared to a smaller subset with one or more basal electrodes deactivated to ascertain any significant differences in speech perception. Methods: A retrospective review of a single CI centre database (from 2011-2021) in [BLINDED], using a Mid-Scala electrode, with focus on recipients identified with one or more deactivated basal electrodes was performed. Comparisons between conventional users and the deactivated cohort included aided pure tone testing in sound field and open-set sentence recognition scores (AzBio) at one-year post activation. Subjective measures were collected to assess overall satisfaction with devices. Results: 48 individuals out of 167 adult recipients had selected for deactivation of basal electrodes. Reasons for deactivation included sound quality and lack of sound percept. There were no significant differences in pre-operative status or demographics between the two cohorts. T-Test analysis found significant differences in aided thresholds between the “intact” and “deactivated” electrode cohorts at 4KHz and 6KHz (p <0.01). Mean post-operative speech perception was also significantly worse in the “deactivated” cohort (48.5% compared to 59.0%) at 1-year post activation (p<0.01). There were no significant differences found between groups in overall satisfaction with their CI. Conclusion: Patient request for basal electrode deactivation owing to subjective sound quality illustrates decreased audibility and speech perception, however CI satisfaction is preserved.