Hearing Preservation and Efficacy Outcomes in CI632 Recipients with Sloping High-Frequency Hearing Loss: Multicenter Trial Results.

INTRODUCTION

Adults with substantial residual low-frequency (LF) hearing are increasingly considered for cochlear implantation. This study evaluated hearing preservation and speech performance outcomes using a slim perimodiolar electrode (CI632) in adults under expanded indications.

METHODS

In a prospective, open-label, single-arm feasibility trial at three US tertiary centers, ten adults with LF thresholds ≤50 dB HL at 500 Hz, sloping high-frequency loss, and aided CNC scores ≤60% in the ear to be implanted received the CI632 device. Participants were followed for 12 months postactivation. Assessments included air and bone conduction audiometry, electrode impedances, unilateral and bilateral CNC in quiet and AzBio sentences in noise, patient-reported outcomes, and postoperative computerized tomography (CT) imaging.

RESULTS

The LF pure-tone average (125-500 Hz) showed a mean shift of 19.3 dB at activation and remained stable at 22.4 dB at 12 months. Impedances were stable across visits. Due to preserved acoustic hearing, all participants utilized electric-acoustic stimulation in the implant ear. Speech recognition improved significantly across all measures, with an average improvement at 12 months ranging from 22 to 54 percentage points, depending on the condition. Patient-reported outcomes also improved. CT imaging confirmed scala tympani placement for all electrodes, with a mean angular insertion depth and wrapping factor of 406.6° and 59.4%, respectively.

CONCLUSION

The slim perimodiolar electrode can preserve LF acoustic hearing in adults implanted under expanded indications, with meaningful improvements observed in both objective and subjective outcomes. Hearing preservation outcomes in this cohort exceeded those typically reported for perimodiolar arrays. While all participants achieved functionally aidable hearing preservation, the small sample size limits the generalizability of this finding, and larger studies are needed to confirm these results.