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

Introduction: Subtotal resection (STR) of vestibular schwannoma (VS) tumors remains controversial and little is known regarding post-operative volume changes. Methods: Authors retrospective reviewed the medical records from January 1st 2002 to January 1st 2018, for all patients who had undergone primary STR of large VS at a single tertiary academic institution. Results: Our 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 3.9 cm (median 3.0 cm; range 1.6–6.0 cm) and 11.7 cm ³ (median 9.6 cm ³ ; range 2.8–44.3 cm ³ ), respectively, with a mean extent of resection of 86% (median 90%; range 53–99%). The mean radiographic and clinical follow-up was 40 months (range 6–120 months) and 51 months (range 7–141 months), respectively. 85% of patients had optimal House–Brackmann (HB) scores (Grade 1 & 2) immediately post-operatively, and 91% at 1 year; 94% of patients had normal (HB 1) at last follow-up. There was significant regression of residual tumor volume at 1 year (p = 0.006) and 2 years (p = 0.02), but not at 3 years (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). Conclusion: Excellent 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.