A nomogram to predict long-term facial nerve function after vestibular schwannoma resection: a contemporary multi-institutional study

Abstract

OBJECTIVE The objective of this study was to develop a nomogram to predict long-term facial nerve (FN) function after vestibular schwannoma (VS) resection. METHODS A retrospective cohort study of two tertiary academic skull base referral centers was performed. Consecutive adults > 18 years of age with sporadic unilateral VS who underwent resection between September 2016 and May 2021 were included. FN function in the immediate postoperative period and at the most recent evaluation was measured. RESULTS A total of 306 patients (mean age 49 years, 63% female) were included, with a mean follow-up of 18 months. The mean maximum tumor diameter was 19 mm (range 1–50 mm), and 80 (26.1%) tumors were > 25 mm. Overall, 85% of patients showed good immediate postoperative FN function (House-Brackmann [HB] grade I or II) and 89% maintained good FN function at > 12 months of follow-up. An intraoperative FN electromyographic (EMG) response ≥ 100 µV to 0.05 mA of stimulation (OR 18.6, p < 0.001) was the strongest predictor of good HB grade in the immediate postoperative period. EMG response ≥ 100 µV (OR 5.70, p < 0.001), tumor size ≤ 25 mm (OR 3.09, p < 0.05), and better immediate postoperative HB grade (OR 1.48, p = 0.005) predicted good long-term FN function on multivariable analysis. A point-of-care nomogram based on these data predicted long-term FN function with a sensitivity of 89% and specificity of 69%. CONCLUSIONS Better immediate postoperative HB grade, intraoperative FN EMG response ≥ 100 µV, and tumor size ≤ 25 mm strongly predicted good long-term FN function after VS resection. A point-of-care nomogram based on these variables could serve as a useful tool for postoperative counseling and prognosis of long-term FN recovery.