The Association of Vestibular Schwannoma Volume With Facial Nerve Outcomes After Surgical Resection

Objective To explore the relationship between tumor size and facial nerve outcomes following vestibular schwannoma (VS) resection. Study Design Single institutional retrospective chart review of all adult patients with untreated sporadic VS who underwent surgical resection from 2008 to 2018 with preoperative magnetic resonance imaging (MRI) and 1 year of follow-up. The primary outcome measure was facial nerve outcome as assessed by the House-Brackmann facial nerve grading system. Results One hundred sixty-seven patients, 54.5% female, with a median age of 49 years (20-76 years), were identified who underwent VS resection. Surgical resection was performed by translabyrinthine (76.7%), middle cranial fossa (14.4%), retrosigmoid (7.2%), and transpromontorial (1.8%) approaches. The median tumor diameter and volume were 25.3 mm (range: 4.1-47.1 mm) and 3.17 cm(3)(range: 0.01-30.6 cm(3)), respectively. The median follow-up was 24.2 months (range: 12-114.2 months). Gross total resection was performed in 79% of cases, with residual tumor identified on MRI in 17% of cases. For patients with tumors <3 cm(3), 92.7% had grade 1 or 2 facial function after at least 1 year follow-up, compared to 81.2% for those with tumors >3 cm(3)(univariate logistic regression OR = 2.9,P= .03). Tumor volume >3 cm(3)was predictive of facial weakness on multivariate regression analysis (OR = 7.4,P= .02) when controlling for surgical approach, internal auditory canal extension, anterior extension, age, gender, and extent of resection. Conclusions Tumor volume >3 cm(3)is associated with worse facial nerve outcomes 12 months following surgical resection. Level of Evidence IVLaryngoscope, 2020