Gamma Knife Radiosurgery for Hemorrhagic Cavernous Malformations

ABSTRACT

OBJECTIVE: In patients with hemorrhagic cavernous malformation(CMs) located in critical brain region that were thought to pose an excessive risk for microsurgical resection, Gamma Knife radiosurgery(GKRS) has been used as an alternative management option for these lesions. The purpose of this study is to evaluate the efficacy of GKRS for hemorrhagic CMs. METHODS: Among the patients of hemorrhagic CMs who had been treated by using Leksell Gamma Knife, 20 patients who had been followed up more than 2 years were analysed for their postradiosurgical results. RESULTS: Mean target volume was 3199mm3(224-9300mm3). Mean maximal dose was 28.9Gy(15-50Gy) and mean marginal dose was 16.5Gy(9-25Gy). 50% isodose or greater was used for the margins of the lesions. Mean follow-up period after GKRS was 51 months(24-112months). During the follow-up period, 3 patients suffered from rebleeding at 5, 6, and 28 months after radiosurgery, respectively. Two cases had a rebleeding in latency period(time interval from GKRS to its maximal effect on vascular obliteration, usually 2-4 years in case of CMs) and another one case after latency period. The annual rebleeding rate was 3.1%(first 2 years after radiosurgery 5%, thereafter 1.7%). Delayed radiation-induced complications occurred in 4 cases at 4, 7, 15 and 18 months after radiosurgery. CONCLUSION: The use of GKRS as an alternative management strategy to the hemorrhagic CMs which located in critical brain region and so had potential risk for microsurgical resection is thought to be available. And the GKRS would reduce the rate of rebleeding of CMs, especially after 2-3 years of latency periods.