Radiosurgery for cavernous malformations in basal ganglia, thalamus and brainstem.

Long-term results of radiosurgery for cavernous malformations in basal ganglia and the brainstem are presented. Eighty-four cases, 50 males and 34 females, ranging in age from 10 to 68 years (mean: 38.2 years) are described. The lesions were located in the brainstem (63), thalamus (14) or basal ganglia (7). The mean lesion size was 14.3mm. Mean maximum and marginal treatment doses were 23.3 and 13.4 Gy, respectively. Brainstem lesions were significantly smaller than the lesions in basal ganglia and the thalamus. During a mean follow-up of 55 months, nearly half of the lesions showed some shrinkage, while in the other half there were no obvious changes. Only 4 of the 84 (4.8%) showed progression. Rebleeding occurred in 14 cases (16.7%),16 times in total. Among these, 12 hemorrhages occurred during the first 24 months after radiosurgery, and the incidence decreased markedly thereafter. Bleeding rates during the first and second years were 9.5 and 4.7%/year/case, respectively. However, the rate significantly decreased thereafter. As for complications, perifocal edema was seen in 18% of basal ganglia-thalamus and in 3.2% of brainstem lesion cases. In conclusion, radiosurgery for cavernous malformations of the basal ganglia-thalamus and brainstem is warranted because a decreased bleeding rate and lower morbidity can be expected.