Cochlear Patency After Translabyrinthine Vestibular Schwannoma Surgery

Objectives:To determine the temporal occurrence of fluid signal changes on T2-weighted magnetic resonance imaging (T2MRI) that occur in the cochlear lumen after translabyrinthine surgery.Study Design:Retrospective case control study.Setting:Tertiary referral neurotology center.Subjects and Methods:Seventy-one patients were identified who underwent translabyrinthine removal of a vestibular schwannoma between 2010 and 2014; of these 49 were included as they had postoperative T2 MRI at 6, 18, and 48 months available postsurgery. Magnetic resonance imaging scans were scored base on fluid signal changes within the cochlea.Results:In total, 147 magnetic resonance imaging scans were reviewed on 49 patients. In the cohort analysis 86% of patients showed evidence of fluid signal changes 48 months postoperatively. Ninety-five percent of patients who went on to demonstrate loss of fluid signal at 48 months had already shown changes at 6 months postsurgery. The majority of cochlea signal changes identified at 6 months were minor (72% Grade 1) while at 48 months this had progressed to severe (71% Grade 2 or 3). Of the patients with a normal cochlea at 6 months 78% maintained a normal cochlea to the 48-month scan.Conclusion:Cochlear signal changes suggestive of fibrosis occurred in most patients following translabyrinthine removal of vestibular schwannoma. Given the early onset of cochlear fluid signal changes on T2MRI, and the progression of these changes on subsequence imaging, cochlear implantation would ideally need to be performed either simultaneous to translabyrinthine surgery or as an early second-stage procedure to maximize the chance of a successful electrode insertion, or one can consider a placeholder as well.