Outcomes of large vestibular schwannomas following subtotal resection: early post-operative volume regression and facial nerve function

IntroductionSubtotal resection (STR) of vestibular schwannoma (VS) tumors remains controversial and little is known regarding post-operative volume changes.MethodsAuthors retrospective reviewed the medical records from January 1st 2002 toJanuary 1st2018, for all patients who had undergone primary STR of large VS at a single tertiary academic institution.ResultsOur series consists of 34 patients with a mean age of 53.9 (median 53; range 21-87) years that had STR of their VS tumor. The mean pre-operative tumor diameter and volume was 3.9cm (median 3.0cm; range 1.6-6.0cm) and 11.7cm(3) (median 9.6cm(3); range 2.8-44.3cm(3)), respectively, with a mean extent of resection of 86% (median 90%; range 53-99%). The mean radiographic and clinical follow-up was 40months (range 6-120months) and 51months (range 7-141months), respectively. 85% of patients had optimal House-Brackmann (HB) scores (Grade 1 & 2) immediately post-operatively, and 91% at 1year; 94% of patients had normal (HB 1) at last follow-up. There was significant regression of residual tumor volume at 1year (p=0.006) and 2years (p=0.02), but not at 3years (p=0.08), when compared to the prior year. There was significant regression of size over time, with a mean slope estimate of -0.70 units per year (p<0.001).ConclusionExcellent clinical facial nerve outcomes can be obtained with STR of large VS tumors. Maximal reduction in tumor size occurs at 2-year post-operatively. Thus, in patients undergoing surgery for large VS, STR and a watch and wait strategy is a reasonable treatment option that may optimize facial nerve outcomes.