Vestibular Schwannoma Cerebellopontine Angle Position Impacts Facial Outcome.

OBJECTIVES/HYPOTHESIS: To determine the impact of vestibular schwannoma (VS) position relative to the internal auditory canal (IAC) on postoperative facial nerve function and extent of surgical resection. STUDY DESIGN: Retrospective chart review. METHODS: Retrospective review of patients undergoing resection of large (≥25 mm) VSs. Outcome measures included early (≤1 month) facial function, long-term (≥1 year) facial function and extent of resection. Tumor measurements included the greatest dimension, dimension anterior to the IAC axis, dimension posterior to the IAC axis, and a ratio of posterior-to-anterior dimension (PA ratio). RESULTS: A total of 127 patients met inclusion criteria. In early follow-up, 60% patients had good (House-Brackmann I-II), and 40% patients had poor (House-Brackmann III-VI) facial function. In long-term follow-up, 71% patients had good, and 29% patients had poor facial function. A total of 72% of patients underwent gross total resection (GTR) of their tumors. Patients with good facial function had significantly larger PA ratios than patients with poor function both early and long term; however, greatest dimension was the more clearly significant independent predictor of facial outcomes. A larger PA ratio was observed in patients in whom GTR was achieved, but this association was potentially confounded by surgeon preferences and was not statistically significant after controlling for surgical site. CONCLUSIONS: This study demonstrates that VS position relative to the IAC axis can be used along with tumor size to predict postoperative facial outcomes. A greater proportion of tumor posterior to the IAC axis was associated with significantly better facial outcomes. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:1093-1098, 2022.