Cochlear Fibrosis after Vestibular Schwannoma Resection via the Middle Cranial Fossa Approach

Abstract

<b><i>Objective:</i></b> The aim of this study was to determine the incidence of cochlear fibrosis after vestibular schwannoma (VS) resection via middle cranial fossa (MCF) approach. <b><i>Design:</i></b> A retrospective case review was conducted. <b><i>Setting:</i></b> The review was conducted in a tertiary care academic medical center. <b><i>Participants:</i></b> Patients who (1) underwent resection of VS via MCF approach between 2013 and 2018, (2) had complete pre- and post-audiometric testing, and (3) had clinical follow-up with magnetic resonance imaging (MRI) for at least 1 year after surgery were included. <b><i>Main Outcome Measure(s):</i></b> The main outcome of this study was cochlear fibrosis as assessed by MRI 1 year after surgery. <b><i>Results:</i></b> Fifty-one patients underwent VS resection via MCF technique during the study period. Of 31 patients with AAO-HNS class A or B preoperative hearing ability, 18 (58.0%) maintained class A, B, or C hearing postoperatively. Of 16 patients who lost hearing and had MRI 1 year after surgery, 11 (61.1%) had MRI evidence of fibrosis in at least some portion of the labyrinth and 4 (22.2%) showed evidence of cochlear fibrosis. Of 16 patients with preserved hearing and MRI 1 year after surgery, 4 (25%) had fibrosis in some portion of the labyrinth, with no fibrosis in the cochlea. <b><i>Conclusions:</i></b> In patients who lose hearing during VS resection with the MCF approach, there is usually MRI evidence of fibrosis in the labyrinth 1 year after surgery. However, there is also, but less commonly, fibrosis involving the cochlea. It is unclear if this will affect the ability to insert a cochlear implant electrode array.