Numerical Study of Facial Nerve Stimulation After Cochlear Implant Surgery

Cochlear implants (CI) have been widely used because it has been proven to help severe to profound hearing problem. Although cochlear implants have been successfully helping patients with hearing loss, some problems remain to occur these days as side effects of cochlear implantation. After the implantation, one of the unpleasant feelings experienced by patients is facial nerve stimulation (FNS) with intra cochlear electrical stimulation. FNS is the presence of any facial movement at or below the maximum comfortable loudness level (the socalled C-level) on one or more electrodes. Previous research suggested that triphasic pulse is better compared to biphasic pulse at reducing FNS. In this research, 3D geometry modeling of the facial nerve and potential field measurements for biphasic and triphasic pulse with different signal waveforms is conducted. This study aims to compare several types of triphasic signal forms to determine which type of signal is the best to reduce FNS. From the various maximum potentials generated, it can be concluded that the best triphasic pulse waveform is the symmetrical waveform, which produces the lowest maximum potential.