STEREOTAXIC RADIOSURGERY OF SKULL BASE MENINGIOMAS

Between April 1992 and February 1996, 97 patients with skull base meni ngiomas were treated at our department. The age of these patients rang ed from 10 to 80 years. The male/female ratio was 1/2. Fifty-three of these patients had primary open surgery for partial removal or recurre nt growth and subsequent radiosurgical treatment. Radiosurgery was per formed as a primary treatment in 44 patients. The mean tumor volume wa s 13.7 cm(3) (range: 0.8-82 cm(3)). These tumor volumes could be cover ed by mean isodose volumes of 45% (range: 20-70%) and were treated by a mean dose of 13.8 Gy (range: 7-25 Gy) at the tumor border. Six patie nts underwent radiosurgery with a staged treatment protocol with 4.6-6 months interval. In 78 patients, a total of 102 follow-up scans were available. The remaining 19 patients have not been included in the pos t-radiosurgical evaluation since the observation time was either too s hort or the patients were lost for follow-up. The mean interval betwee n gamma knife treatment and last follow-up scan was 18.5 months, with a range from 6 to 46 months. Follow-up imaging (CT, MRI or both) revea led a decreased volume of the tumor in 31 cases (40%). In 44 cases (56 %), tumor progression was stopped, and in 3 cases (4%) increased tumor volumes could be observed. In 8 cases marked central tumor necrosis w as seen. Neurological follow-up examinations in 76 patients showed a s table neurological status in 71%, ameliorated status in 24% and worsen ing in 5% of the patients.