SURG-03: SURGERY AFTER RADIATION THERAPY FOR VESTIBULAR SCHWANNOMAS

INTRODUCTION: Surgery for vestibular schwannomas after radiation therapy failure is associated with increased technical difficulty, incomplete resection, and deterioration in facial nerve function. (Limb 2005, Iwai 2007, Lee 2010, Husseini 2013, Hong 2013) We report our experience with surgery for vestibular schwannomas after radiation with regards to extent of resection and preservation of facial nerve function. METHODS: This retrospective study was approved by the institutional review board. Patients who underwent surgery for vestibular schwannoma after failing initial radiation therapy, were included in the study. Exclusion criteria included prior surgery. Patient demographics, surgical approach, tumor size, intraoperative findings, extent of resection, and pre- and post-operative House-Brackmann (HB) scores were reviewed. Extent of resection was classified as gross total resection (GTR, no residual tumor), near total resection (NTR, less than 5mm of tumor along the brainstem or nerve), or subtotal resection (STR, greater than 5mm residual tumor). RESULTS: Between 2004 and 2015, ten patients underwent surgery after failing initial radiation therapy. One patient who had undergone prior surgical resection was excluded. Indications for surgery included tumor progression on magnetic resonance imaging with or without symptoms of mass effect and cranial nerve dysfunction. The mean maximal tumor diameter prior to surgery was 2.1 cm. The mean interval between radiation therapy and surgery was 3.3 years (range 2-5 years). All patients had a preoperative HB score of 1. Six cases involved a translabyrinthine approach, resulting in five GTR's and one STR. NTR was achieved in two cases through a retrosigmoid approach. At a mean follow-up of 3 months (range 1-85 months), eight patients were HB 1 and two patients were HB 4 (both underwent GTR). CONCLUSIONS: Despite increased technical difficulty, extensive resection of vestibular schwannomas can be achieved after radiation therapy with reasonably good preservation of facial nerve function.