[The comparison between adult and pediatric AVMs treated by gamma knife radiosurgery]

More than 290 cases of cerebral AVM had been treated by gamma knife radiosurgery since May, 1991, among which ninety-nine cases were angiographically followed up for at least one year. Comparison of the results between adult and pediatric AVMs were made. There were seventy six adult and twenty three child cases. Intracerebral hemorrhages in their past history were found in 73.7% of adult and 91.3% of child cases respectively, and the rate of intracranial hemorrhages in the pediatric group was higher than that in the adult group. The volume of the nidus of AVM in both groups was 4.2 ml in adults and 4.8 ml in children. Grade III of the Spetzler grading system occupied about 70% of all cases and was the most common grade in both groups. Treatment was performed with a mean marginal dose of 20.0Gy in adults and 20.5Gy in children. The complete occlusion of the nidus was obtained in 45% of the adult group and 74% of the pediatric group one year after, and in 81% and 95% respectively two years after the treatment was begun. As side effects, these were two rebleedings, one radiation necrosis and one radiation-induced edema in adults. However, no side effects were observed in children. It is considered that, when using gamma knife radiosurgery, pediatric AVMs are more likely to be occluded successfully and safely than adult AVMs.