Object: Studies on the efficacy of arteriovenous malformation (AVM) radiosurgery have largely been conducted in the adult population. Clinically, the results may not always be applicable to pediatric patients. Moreover, studies involving the pediatric population have largely comprised small- (< 3 cm3) and medium-sized (3-10 cm3) AVMs. For large (> 10 cm3) AVMs in children, sparse radiosurgical results are available. The current study was conducted to further clarify the role of radiosurgery in the treatment of pediatric AVMs.
Methods: A retrospective analysis was performed of data obtained in 105 pediatric patients (< 18 years of age) with cerebral AVMs treated by Gamma Knife surgery (GKS) between 1993 and 2006. For statistical comparison the authors studied data acquired in 458 adult patients with AVMs treated during the same period. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Cerebral angiography was used to confirm the obliteration of the AVM.
Results: In pediatric patients, the AVM obliteration rate at 48 months after a primary GKS was 65%. Repeated GKS in those in whom primary treatments failed further ablated some AVMs, for an overall obliteration rate of 81%. The efficacy of GKS correlated with the size of the AVM: 91% for small, 86% for medium, and 64% for large AVMs. The treatments were associated with an 8% morbidity rate and < 1% mortality rate. Posttreatment hemorrhage occurred in 4 (4%) of 105 patients. Obliteration rates at 48 months of small and extremely large (> 20 cm3) AVMs were similar in the pediatric and adult groups, whereas AVMs between 3 and 10 cm3 responded less efficaciously in children (p = 0.042). The AVMs with volumes ranging from 10 to 20 cm3 were also associated with a lower obliteration rate in children at 48 months, but statistical significance was not reached (p = 0.279).
Conclusions: Gamma Knife surgery is an effective and safe treatment alternative for pediatric AVMs. The medium (3-10-cm3) and large (10-20-cm3) AVMs tend to respond less efficaciously than those of comparable size in adults.