Preclinical Testing for Evaluating the Performance of a Direct Acoustic Cochlear Implant

A standard method for preclinical testing of direct acoustic cochlear implants (DACIs) does not exist. This study investigated the possibility of using a temporal bone model to predict the clinical outcome of a DACI. The DACI performance in temporal bones was calculated using intracochlear pressure measurements and round window membrane velocities (n=22). The performance was expressed as the sound pressure level of an equivalent sound source in free-field (equivalent sound pressure level, eqSPL). The temporal bone experiments reflected the clinical situation, i.e. the stapes was immobilized before inserting the actuator prosthesis through a laser stapedotomy. Tisseel fibrin glue around the stapedotomy and implant was applied to mimic tissue growth in patients. The DACI performance in patients was calculated based on audiometric data from 47 patients implanted with the device and device specifications of the manufacturer. Only DACI patients with a fixed stapes footplate were included in this study. The predicted eqSPL from temporal bone experiments ranged between 90-120 dB SPL. The experimental data matched the clinical data at low and high frequencies. However, in the mid frequency range (1-3 kHz), the temporal bone model underestimated the performance of the DACI in patients by 10-20 dB. Sealing the stapedotomy and applying fibrin glue around the actuator and round window lead to a slight increase in the output of the DACI at low frequencies, but could not account for the differences between the temporal bone data and clinical data observed in the mid-frequency range. The temporal bone model is a feasible method to predict the performance of a DACI, although the clinically observed output at mid-frequencies is underestimated by 10-20 dB.

Poster-PDF A-1287.pdf

Deutsche Forschungsgesellschaft, Cluster of Excellence, Hearing4all; Cochlear Ltd.

Publication History

Article published online:
13 May 2021