Gamma knife radiosurgery of the brain stem cavernomas

Over 6 years (1992-1998) 26 patients with brain stem cavernomas were treate d using the Leksell gamma knife in Prague. 25 patients had a follow up of 6 -66, median 24 months. Annual risk of bleeding before radiosurgery was 4%, After gamma knife treatment sudden impairment of neurodeficit reported as r ebleeding was observed in 4 patients at 6-51 months, median 16.5 months, af ter radiosurgery. This represented a 6.8% risk of rebleeding after radiosur gery, which is not significantly different from the risk before radiosurger y. MRI or CT was performed in 24 patients 6-48, median 24, months after rad iosurgery. There were no signs of rebleeding in any of the patients, nor an y increase of the cavernoma. A decrease of cavernoma size was observed in 8 (33%) of patients. Temporary collateral edema after radiosurgery was detec ted in 5 (21%) of patients 3-12, median 11, months after radiosurgery. Neur odeficit was observed in 21 of 26 patients before radiosurgery. Improvement of the neurodeficit was detected in 9 (43 %) of them 6 - 36, median 8, mon ths after radiosurgery, Temporary morbidity caused by collateral edema or r ebleeding occurred in 7 patients (28 %) and permanent morbidity remained in 2 patients (8 %). 2 patients died because of rebleeding 6 and 51 months af ter radiosurgery and the third patient for unrelated reason. Radiosurgery o f the brain stem cavernomas was indicated when there was bleeding in the hi story or progressive neurodeficit and microsurgery was considered too risky . Leksell gamma knife radiosurgery of cavernomas has proved its low morbidi ty and zero mortality. In case of an insufficient effect of radiosurgery, o r if the protective effect from rebleeding comes too late, morbidity and mo rtality can correspond to the natural course of the disease, as it was left without any treatment.