Single Institutional Experience With Observing 564 Vestibular Schwannomas: Factors Associated With Tumor Growth

Objective: To characterize the risk and predictors of growth during observation of vestibular schwannomas (VS). Study Design: Retrospective case series. Setting: Single academic, tertiary care center. Patients: Five hundred sixty-four consecutive VS patients who underwent at least two magnetic resonance imaging (MRI) studies before intervention. Intervention(s): Serial MRI studies. Main Outcome Measure(s): Tumor growth, defined as a >= 2mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last study. Results: A total of 1296 patients (1995-2015) with VS were identified. Of those, 564 patients (median age 59.2 years; 53.5% female) were initially observed and underwent multiple MRI studies (median follow-up 22.9 months, interquartile range [IQR] 11.7-42.7). The median maximum tumor diameter at presentation was 1.00 cm (IQR 0.6-1.51 cm). In all, 40.8% of tumors demonstrated growth and 32.1% underwent intervention (21.5% microsurgery, 10.5% radiation) during the surveillance period. Multivariable Cox regression analysis showed that for each tumor, the risk of growth or intervention was significantly increased for larger initial VS diameters (HR = 2.22; 95% CI: 1.90-2.61) and when disequilibrium was a presenting symptom (HR = 1.70; 95% CI: 1.30-2.23). Patient age, sex, aspirin use, and presenting symptoms of asymmetric hearing loss, tinnitus, and vertigo were not associated with tumor growth. Conclusion: To date, this is the largest series of observed VS reported in the literature. Risk of VS growth is significantly increased among patients who present with larger tumors and who have concomitant disequilibrium. IRB: 151481. Define Professional Practice Gap and Educational Need: No cohort with this sample size has assessed vestibular schwannoma growth rates in conjunction with this number of variables. Learning Objective: To characterize vestibular schwannoma growth rates and predictors of growth.