Challenges of Cochlear Implantation in Intralabyrinthine Schwannoma Patients: Surgical Procedures and Auditory Outcome

Abstract

Intralabyrinthine schwannoma (ILS) is a rare benign tumor of the inner ear potentially causing unilateral sensorineural hearing loss and vertigo. This study evaluated the outcome of one surgical session comprising microsurgical ILS resection and cochlear implantation in terms of surgical feasibility, complications, and auditory outcome. Ten clinically and histologically confirmed ILS patients included in this study (three women and seven men; mean age 56.4 ± 8.6) underwent surgery between July 2015 and February 2020. Eight patients had intracochlear tumor location; the remaining two had vestibulocochlear and intravestibular ILS. One of the three following methods was used for tumor removal: an extended cochleostomy, subtotal cochleoectomy, or a translabyrinthine approach. Although negligible improvement was observed in two of the patients, two patients were lost to follow-up, and one opted out from using CI, the speech perception of the five remaining ILS patients improved as per the Freiburg Monosyllable Test (FMT) from 0% before surgery to 45– 50% after the implantation. Our study supports the presented surgical approach’s feasibility and safety, enabling tumor removal and hearing restoration shortly after surgery.

Intralabyrinthine schwannomas: a two-case series and literature review with a focus on hearing rehabilitation

“…Although a case of intracochlear schwannoma excision with hearing preservation was reported [31], cochlear implantation represents the best option for hearing rehabilitation. It can be placed at the time of tumor removal or during a second-stage surgery; in the latter case, a dummy electrode should be inserted in the cochlea to prevent its ossification [31,32,34]. According to the data available in the literature, CI has been successfully carried out in patients affected by different types of ILS (intravestibular, intracochlear, intravestibulocochlear, transmodiolar, transmacular) [25,26,[32][33][34][35][36][37][38]; there is no report of CI after excision of transotic or tympanolabyrinthine tumor.…”

“…Auditory outcomes of CI after ILS surgery have been reported in case series and reports [25,26,[32][33][34][35][36][37][38], providing extremely variable postoperative speech discrimination scores, ranging from 0% up to 100%.…”

“…In terms of hearing rehabilitation, the translabyrinthine approach allows the intracochlear application of a CI through a posterior tympanotomy approach, while drilling the cochlea may prevent the application of a CI, if the modiolus and spiral lamina are not carefully preserved [ 32 , 33 ]; Ma et al have argued that a subtotal excision of the tumor may be acceptable if the purpose is sparing these structures [ 30 ].…”

“…So far, CI appears to be a feasible hearing rehabilitation strategy as long as the modiolus and the spiral lamina are preserved, despite the extent of the tumor [ 32 , 33 ].…”

“…2: 40% – 1 IV Case no. 1: 100% – CI cochelar implantation, CPA cerebello-pontine angle, IC intracochlear ILS, ILS intralabyrinthine schwannoma, IV intravestibular ILS, IVC intravestibulocochlear ILS, TM transmodiolar ILS, TMA transmacular ILS, SDS speech discrimination score a [ 10 , 25 , 31 , 32 , 36 , 38 ] …”