Comparison of Two Precurved Cochlear Implant Electrode Arrays from the Same Manufacturer: Electrophysiological...

This study aimed to investigate differences between two precurved cochlear implant electrode arrays - Contour Advance (CA) and Slim Modiolar Electrode (SME) - in adult users, with a focus on electrically evoked compound action potential (ECAP) thresholds, 1-year postoperative C-levels, and battery consumption.

Data from 70 adult cochlear implant recipients (35 CA, 35 SME) were analyzed. Intra- and postoperative ECAP thresholds were obtained using Cochlear Custom Sound software. One-year C-levels were measured through psychophysical loudness scaling. Estimated battery runtimes were examined in relation to median C-levels. A linear mixed-effects model was used to assess differences across electrode positions and between arrays. Model validation was performed through examination of standardized residuals versus fitted values, QQ-plots analysis, and comparison of observed versus expected serial correlations.

The CA array showed a more linear and more directly proportional relationship between ECAPs and C-levels. The SME array demonstrated significantly higher ECAPs and C-levels for the basal electrodes, larger pre- to postoperative changes in thresholds, and larger differences between ECAPs and C-levels, compared to the CA array. Battery runtime was significantly correlated with C-levels in the CA group, whereas impedance appeared more closely related to battery consumption in the SME group.

Electrode array design affects electrophysiological and behavioral responses as well as battery consumption. We found significant differences between two precurved electrode arrays from the same manufacturer. These findings highlight the importance of array-specific programming strategies and suggest that electrode characteristics should be considered in clinical decision-making and device optimization.