The Influence of Extent of Resection and Tumor Morphology on Facial Nerve Outcomes Following Vestibular Schwannoma Surgery

Objective: To determine the influence extent of resection and tumor characteristics on facial nerve (FN) outcomes following microsurgical resection of vestibular schwannoma (VS). Study Design: Retrospective chart review. Setting: Tertiary referral center. Patients: Three hundred eighty-five patients who underwent VS microsurgical resection. Interventions: Microsurgical VS resection. Main Outcome Measures: House-Brackmann (HB) scores postoperatively. Good FN function was defined as HB grade I and II and poor FN function was defined as HB grade III and VI. Gross total resection (GTR) versus subtotal resection (STR). Propensity-score matching was used in subset analysis to balance tumor volume between the surgical cohorts, followed by multivariable analysis. Results: Seventy-one patients (18%) underwent STR and 314 patients (82%) underwent GTR. Two hundred fourteen patients (63%) had good FN function at 2 to 3 weeks postoperatively, and 80% had good FN function at 1 year. In single predictor analysis, STR did not influence FN function at 2 to 3 weeks (p = 0.65). In propensity-score matched subset analysis (N = 178), patients with STR were less likely to have poor FN function at 2 to 3 weeks (p = 0.02) independent of tumor volume (p = 0.004), but there was no correlation between STR and FN function at 1 year (p = 0.09). Ventral extension of tumor relative to the internal auditory canal plane was associated with poor FN outcomes at 2 to 3 weeks (p = 0.0001) and 1-year postop (p = 0.002). Conclusions: When accounting for tumor volume, STR is protective in immediate postoperative FN function compared to GTR. Ventral extension of the tumor is a clinical predictor of long-term FN outcomes.