SURG-96. Long-Term Reduction in Tinnitus and Vertigo After Stereotactic Radiosurgery for Vestibular Schwannoma: A Meta-Analysis of Over 7,200 Patients

Vestibular schwannoma (VS) is a benign tumor of the vestibulocochlear nerve commonly found on the cerebellopontine angle. VS can present with a variety of vestibular and auditory deficits, notably sensorineural hearing loss, tinnitus, imbalance, and vertigo. Stereotactic radiosurgery (SRS) is a first-line surgical intervention for the management of VS in order to improve symptoms and prevent further tumor growth; however, there is minimal literature on the most optimal application of SRS to produce long-term symptom resolution and tumor control. In this study, we performed a large scale meta-analysis on long-term outcomes after SRS for VS, encompassing 7,281 patients in 58 studies. The median follow-up time for symptom control was 75 months. Radiologic tumor control rate (TCR) across all patients was 93%. The median age of patients was 57 years, and 52% of patients were female. Tumors under 4cm3 in volume had a TCR ranging between 94-95%, while tumors over 4cm3 had a TCR of 87% (p<0.01). TCR in SRS with Proton-Beam, LINAC, and Cyberknife modalities ranged between 96-98%, while TCR in Gamma-Knife was 90% (p<0.01). Tumor control was higher in single-fraction SRS (93%) compared to fractionated SRS (86%) (p=0.01). Pre-operative tinnitus and vertigo were significantly improved after SRS, with odds ratios of 0.63 (p<0.001) and 0.71 (p=0.026), respectively. Our work confirms adequate long-term tumor control after SRS for VS. Of commonly reported VS symptoms, we find that tinnitus and vertigo are most significantly reduced after SRS in a large patient population. Additionally, we demonstrate that tumors treated with single-fraction SRS, Proton-Beam, LINAC, and Cyberknife, as well as those under 4cm3 in volume had significantly higher long-term tumor control. Future research, including randomized control trials, will be necessary in order to further optimize the conditions of SRS that will maximize long-term symptom and tumor control in VS.