The results of radiosurgical management of 72 middle fossa meningiomas.

Of 812 patients with intracranial tumours treated by radiosurgery during the period 1984-1990, 129 had meningiomas. Of these latter, 72 had middle fossa meningiomas. Patients with meningiomas treated by us since March 1990 are not included in this report since we established the investigative principle of a minimum of 30 months follow-up. Seventeen of the 72 patients were treated after incomplete surgical resection, and 21 for tumour regrowth. In 34 patients, radiosurgery was the primary treatment. The tumour volume was calculated by the ellipsoid method. It ranged from 0.588-76.346 ml. Radiosurgery was performed using the non-invasive stereotactic fixation head device (Greitz-Bergström) adapted to the Fixster frame, and dynamic irradiation performed with the linear accelerator, using especially designed collimators. The total tumour dose for each patient ranged from 15-45 Gy. The minimum follow-up was 2 1/2 years and the maximum 8 years. In 50 patients there was tumour shrinkage ranging from 24-91% of the initial tumour volume. Shrinkage was associated with central tumour necrosis in 11 of these 50 patients. In 18 patients the tumour volume remained stable. In 2 patients there was tumour progression and in 2 there was regrowth after initial reduction of tumour volume. There were no significant treatment complications. Radiosurgery is preferable to re-operation in recurrent meningiomas and indicated after incomplete surgical removal. In high risk patients, as well as in "unresectable" meningiomas, it is an obvious alternative to microsurgery.