Long term results of primary radiosurgery for vestibular schwannomas.

Abstract

Stereotactic radiosurgery (SRS) has become a primary option for management for both newly diagnosed vestibular schwannomas (VS), as well as VS that enlarge after initial observation. A retrospective review of our prospectively maintained data base found 871 patients who underwent Gamma knife® SRS as their initial (primary) management between 1987 and 2008. Follow-up ranged from 1-25years (median = 5.2years) Median tumor volume was 0.9cc (0.02-36) and median margin dose was 13Gy (12-25). Progression free survival (PFS) after SRS was 97% at 3years, 95% at 5years, and 94% at 10years. Freedom from delayed surgical resection was found in 98.7% of patients. Smaller tumor volume was significantly associated with improved PFS. There were 326 patients with serviceable hearing (Gardner-Robertson 1 or 2) at the time of SRS with audiological follow-up of ≥ 1year. Serviceable hearing preservation rates after SRS were 89.8% at 1year, 76.9% at 3years, 68.4% at 5years, 62.5% at 7years, and 51.4% at 10years. Factors associated with improved serviceable hearing preservation included younger age, Gardner-Robertson grade 1 at SRS, and absence of subjective complaints of dysequilibrium or vertigo (vestibulopathy). Fifty-one patients (5.8%) developed trigeminal neuropathy. Fourteen (1.6%) developed a transient House-Brackmann grade 2 or 3 facial neuropathy. In this report with extended follow-up, primary SRS achieved tumor growth control in 94% of patients. Optimization of long- term cranial nerve outcomes remains an important achievement of this management strategy for VS.