Intracochlear Auditory Nerve Monitoring and Cochlear Implantation After Total Resection of a Vestibular Schwannoma: Case Report

The aim is to present a case of cochlear implantation (CI) after vestibular schwannoma (VS) resection and intracochlear auditory nerve moni toring. The case of a 53-year-old man with left-sided iatrogenic dehiscence of the posterior semicircular canal after VS resection using the retrosigmoid approach is reported. Because of third mobile window symptoms, transmastoid plugging of the posterior and superior semicircular canal was carried out. In the following 3 years, ipsilateral hearing problems and tinnitus loudness increased, and therefore CI was considered. To investigate the electrophysiological status of the left cochlear nerve, intraoperative auditory nerve monitoring was performed using the Auditory Nerve Test System (ANTS). Audiological assessments included tinnitus evaluation, speech perception in noise, and sound localization. Because reliable electrical auditory brainstem response waveforms were found during intracochlear ANTS testing, supporting the integrity of cochlear nerve function, CI was performed during the same surgery using a flexible 34-mm electrode array. Audiological evaluation 3 months after CI activation showed a significant positive effect of CI usage on tinnitus loudness (8/10 in the CIOFF condition going to 0/10 in the CION condition). Moreover, speech perception in noise and localization testing showed restored binaural hearing in the CION condition. Cochlear implantation was found to be successful in a single-sided deaf case with iatrogenic dehiscence of the posterior semicircular canal after VS resection. Prior to implantation, intraoperative ANTS measurement proved integrity of the cochlear nerve function and therefore has the ability to guide the decision of placing a CI after VS resection in case of preservation of cochlear nerve function.

Cite this article as: Mertens G, Lammers MJ, Vanderveken OM, Rompaey VV. Intracochlear auditory nerve monitoring and cochlear implantation after total resection of a vestibular schwannoma: Case report. B-ENT. 2024;20(1):61-68.