Linac radiosurgery for skull base meningiomas

Introduction. Skull base meningiomas present a difficult surgical challenge because of the high potential morbidity of radical surgical extirpation an d their low potential for incapacitating symptomatology. The focal characte r of meningiomas makes stereotactic radiosurgery an attractive adjuvant tre atment modality to resection. The purpose of this study was to evaluate the local control rates and complications in 56 patients with base of skull me ningiomas undergoing radiosurgery. Methods. Patients underwent radiosurgery using the dedicated stereotactic l inear accelerator at the Brigham and Women's Hospital. Minimal peripheral d oses of radiosurgery ranged from 12 to 18.5 Gy (mean 15 Gy). Doses were des igned to conform to the frequently irregular tumor volumes using the X-Knif e treatment planning system. Multiple isocenters were used when required to increase conformality of dose. For 36 patients (64%), radiosurgery was use d as an adjunct to surgery, for 20 patients (36%) it was the primary treatm ent. Results, Median followup was five years. Nineteen patients (34%) were impro ved clinically at follow-ups 32 (57%) were unchanged; and 5 patients (9%) d eveloped new or worsened neurologic deficits. Serial imaging studies after radiosurgery showed a reduction in tumor volume in 23 patients (41%) 30 (54 %) showed stable disease; 3 patients (5%) had tumors which increased in siz e (2 being outside the radiosurgery treatment site). The actuarial freedom from progression rate (defined as further tumor growth) was thus 95% with a median imaging follow-up of 26 months (range, 6-66 months). Although further follow-up is necessary. the results of this series clearly demonstrate that these lesions are feasible for treatment by modern radios urgical techniques. Linac radiosurgery can stabilize skull base meningiomas , with decreased or unchanged tumor volumes on radiologic follow-up in appr oximately 95% of patients. Radiosurgery is a low-morbidity, effective techn ique as adjunct and sometimes primary treatment of small to moderate-sized meningiomas of the skull base.