Electrode deactivation in cochlear implant users: impact on speech perception and objective measures

Purpose  To verify whether electrode deactivation in cochlear implant users results in modifications in silent and noisy speech recognition, as well as to identify whether changes occur in electrical and physiological measurements.

Methods  Retrospective study of medical records of 46 cochlear implant users, from three manufacturers, who underwent deactivation of at least one electrode. Pre- and post-deactivation data relating to programming records, free-field audiometry (500, 1,000, 2,000 and 4,000 Hz) and sentence recognition tests recorded in silence at 60 dB and with competing noise at +10 dB signal-to-noise ratio. Objective measurements included impedance telemetry, electrically elicited stapedial reflex (eSRT) and electrically evoked compound action potentials (ECAP). Statistical analyses used the Wilcoxon test, Spearman correlation, and chi-square test, with a significance level of 5%.

Results  Statistically significant correlations were observed in the thresholds at 1,000 and 4,000 Hz in the 46 users studied, but without functional impact on overall averages or speech perception between pre- and post-deactivation assessments. Objective measures showed significant changes, including an increase in electrodes with altered impedance (2.2% to 13%; p = 0.009) and a reduction in the presence of ECAP responses (53.8% to 28%). The eSRT had a limited number of measurements, restricting the analysis.

Conclusion  Electrode deactivation, when clinically indicated, did not compromise functional auditory performance, although it was accompanied by electrical and physiological changes. These findings reinforce the need for comprehensive monitoring and individualized management.

Keywords:
Audiology; Hearing Loss; Cochlear Implant; Speech Perception; Evoked Potentials; Auditory Rehabilitation; Electrodes; Electrical Impedance