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

Objective: This study was aimed to determine the timing and incidence of cochlear ossification after vestibular schwannoma resection via the middle cranial fossa approach.

Study Design: This study is a retrospective case review.

Setting: The study was conducted at a tertiary care academic medical center.

Patients: Inclusion criteria were (1) patients who underwent resection of vestibular schwannoma (VS) via middle cranial fossa (MCF) approach between 2013 and 2018, (2) had complete pre and postaudiometric testing, and (3) clinical follow-up with magnetic resonance imaging (MRI) for at least 1 year after surgery.

Intervention: In this study, resection of vestibular schwannoma via middle cranial fossa approach was done.

Main Outcome Measure: Primary outcome was Cochlear ossification as assessed by MRI 1 year after surgery.

Results: A total of 51 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 imaging 1 year after surgery, 11 (61.1%) had MRI evidence of ossification in at least some portion of the labyrinth, and 4 (22.2%) showed evidence of cochlear ossification. Of 16 patients with preserved hearing and MRI imaging 1 year after surgery, 4 (25%) had ossification in some portion of the labyrinth, with no ossification in the cochlea.

Conclusion: In patients who lose hearing during VS resection with the MCF approach, there is usually MRI evidence of ossification in the labyrinth 1 year after surgery. However, there is also, but less commonly, ossification involving the cochlea. It is unclear if this will affect the ability to insert a cochlear implant electrode array even if the cochlear nerve and blood supply is preserved.

Publication History

Article published online:
12 February 2021