Conservative Management or Gamma Knife Radiosurgery for Vestibular Schwannoma: Tumor Growth, Symptoms, and Quality of Life

BACKGROUND:There are few reports about the course of vestibular schwannoma (VS) patients following gamma knife radiosurgery (GKRS) compared with the course following conservative management (CM). In this study, we present prospectively collected data of 237 patients with unilateral VS extending outside the internal acoustic canal who received either GKRS (113) or CM (124). OBJECTIVE:The aim was to measure the effect of GKRS compared with the natural course on tumor growth rate and hearing loss. Secondary end points were postinclusion additional treatment, quality of life (QoL), and symptom development. METHODS:The patients underwent magnetic resonance imaging scans, clinical examination, and QoL assessment by SF-36 questionnaire. Statistics were performed by using Spearman correlation coefficient, Kaplan-Meier plot, Poisson regression model, mixed linear regression models, and mixed logistic regression models. RESULTS:Mean follow-up time was 55.0 months (26.1 standard deviation, range 10-132). Thirteen patients were lost to follow-up. Serviceable hearing was lost in 54 of 71 (76%) (CM) and 34 of 53 (64%) (GKRS) patients during the study period (not significant, log-rank test). There was a significant reduction in tumor volume over time in the GKRS group. The need for treatment following initial GKRS or CM differed at highly significant levels (log-rank test, P < .001). Symptom and QoL development did not differ significantly between the groups. CONCLUSION:In VS patients, GKRS reduces the tumor growth rate and thereby the incidence rate of new treatment about tenfold. Hearing is lost at similar rates in both groups. Symptoms and QoL seem not to be significantly affected by GKRS. ABBREVIATIONS:CM, conservative managementCPA, cerebellopontine angleGKRS, gamma knife radiosurgeryIAC, internal acoustic canalGR, Gardner-RobertsonKM, Kaplan-MeierMS, microsurgeryQoL, quality of lifeRS, radiosurgerySD, standard deviationSF-36, 36-item short-form health surveyVAS, visual analog scaleVS, vestibular schwannoma