Multivariate Analysis of Factors Influencing Facial Nerve Outcome following Microsurgical Resection of Vestibular Schwannoma

Objective To assess through multivariate analysis the clinical pre- and intraoperative factors of facial nerve outcomes at day 8 and 1-year recovery of facial palsy, as compared with day 8 status among patients who underwent total resection of unilateral vestibular schwannoma. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods This study included 229 patients with preoperative normal facial function and anatomic preservation of the facial nerve. Clinical, radiologic, and intraoperative factors were assessed according to facial nerve function at day 8 and 1 year. Results We observed that 74% and 84% of patients had good facial function (House-Brackmann [HB] I-II) at day 8 and 1 year, respectively. Of 60 patients, 26 (43%) who had impaired facial function (HB III-VI) at day 8 recovered good facial function (HB I-II) 1 year after surgery. A structured equation model showed that advanced tumor stage and strong facial nerve adhesion were independently associated with facial nerve conduction block at day 8. No predictive factor of impaired facial function recovery was seen at 1 year. In terms of the extracanalicular diameter of the tumor, the cutoff point to minimize the risk of impaired facial function was 16 mm. Conclusion At day 8 after vestibular schwannoma resection, facial function was impaired in the case of large tumors or strong facial nerve adhesion to the tumor. After 1 year, less than half of the patients recovered good facial function, and no predictive factor was found to be associated with this possible recovery.