Gamma knife radiosurgery for cerebellopontine angle meningiomas
Robert M. Starke, Claire Hiles, James H. Nguyen, Ching-Jen Chen, Dale Ding and Jason P. Sheehan
Objective: Cerebellopontine angle (CPA) meningiomas are complex lesions for which complete resection can sometimes lead to significant morbidity or mortality. In this study, we evaluate the outcomes of CPA meningiomas treated with Gamma Knife radiosurgery (GKRS).
Methods: We performed a retrospective review of a prospectively compiled database evaluating the outcomes of 43 patients with CPA meningiomas treated at the University of Virginia from 1990 to 2006. There were 36 females and 7 males with a median age of 65 years (range 30-79). Twenty-eight were treated with primary radiosurgery, and 15 patients were treated with adjuvant radiosurgery after surgical resection. Patients were assessed clinically and radiologically at routine intervals following GKRS. Kaplan-Meier analysis was used to assess tumor progression.
Results: The mean follow-up was 5 years (range 2-16 years). The mean pre-radiosurgery tumor volume was 5.2 cm3 (range 0.3-17cm3). At last follow-up, 37 patients (86%) displayed either no growth or a decrease in tumor volume. Six (14%) patients displayed an increase in volume. Kaplan Meier analysis demonstrated radiographic progression free survival at 3, 5, and 10 years to be 95%, 95%, and 73%, respectively. At last clinical follow-up, 40 patients (93%) demonstrated no change or improvement in their neurological condition and 3 patients clinically declined (7%). One of four patients with pre-treatment facial nerve weakness had improvement following GKRS. Two of 19 patients with hearing decline prior to GKRS had improvement and 1 patient had a decline following treatment. Comparing patients with and without extension into the internal auditory canal, there was no statistically significant difference in facial nerve status and hearing complications after GKRS.
Conclusions: GKRS offers a reasonable rate of tumor control for CPA meningiomas, and acm3omplishes this with a low incidence of new or worsening neurological deficits.
Keywords: Radiosurgery, gamma knife, meningioma, cerebellopontine angle