Gamma Knife radiosurgery of brainstem gliomas

From August 1992 until December 1999 Gamma Knife radiosurgery (GKRS) was applied to 21 patients (male to female ratio 14:7) with brainstem gliomas. Patient's median age was 23 years (8-56 years). All tumours were histologically confirmed by biopsy or open surgery: 12 low-grade gliomas and 9 malignant growths. Two lesions were located primarily in the medulla, 12 in the pons and 7 in the midbrain. A median dose of 12 Gy (9-20 Gy) was applied to the tumour margin by the median isodose of 45%. Prior to radiosurgery 4 patients were treated by conventional radiotherapy, 1 had radiotherapy and chemotherapy, 1 patient underwent chemotherapy, and 1 patient was shunted due to hydrocephalus. Neuroimaging controls (MR, CT) were obtained from 19 patients. The median interval between radiosurgery and the last neuroimaging control was 11.8 months (1-74 months). Neuroimaging depicted tumour progression in 2 patients, stable disease in 10 patients and regression in 3 cases. Follow-up periods ranged between 3 and 99 months (median 29 months). The neurological state improved in 5 patients. Microsurgical cyst fenestration was performed in 1 patient after GKRS, shunting procedure was necessary for 2 patients. Nine patients died unrelated to radiosurgery within 3 to 45 months (median 20.7 months). GKRS is an effective treatment modality for brainstem gliomas with satisfying tumour control and functional outcome.