Tumor Control of Vestibular Schwannomas after Gamma Knife Radiosurgery

Objectives Gamma Knife radiosurgery (GKRS) has emerged as a viable alternative to surgical resection in the management of vestibular schwannomas (VS). However, long-term tumor control rates have not been well described.

Methods We identified all patients with VS treated from August 1995 to April 2015 who underwent GKRS at the Keck School of Medicine of USC. The prescribed treatment dose was 12.5 Gy to the 50% isodose line. Patients underwent planned surveillance imaging.

Results We included 63 patients with VS who underwent GKRS; 55 had never undergone prior resection, 8 had been previously resected, and 1 underwent previous GKRS. The median age was 60.3 years and the median follow-up time was 53.9 months (range: 1–195 months). The median treatment volume was 1.76 cm³; 93.7% of patients experienced tumor control with no evidence of progression during the follow-up period, resulting in a median progression-free follow-up time of 47 months; 14.3% of patients (9 out of 63) reported decreased hearing during the follow-up period; 1.6% of patients (1 out of 63) developed new facial weakness, present at the last follow-up visit; 1.6% of patients (1 out of 63) required subsequent surgery during the follow-up period.

Conclusion Patients undergoing GKRS for VS had high rates of tumor control (>90%) during the follow-up period of more than 4 years, with low rates of hearing loss and facial nerve palsy. Only one patient required surgery during the follow-up period.