Hemorrhage risk and Radiosurgery outcomes for Pediatric AVM
The International Gamma Knife Research Foundation presented 2 pediatric brain arteriovenous malformations (AVM) reports: 1) the incidence and risk for hemorrhagic presentation, and 2) radiosurgery outcomes. Retrospective review of 357 patients (mean age of 12.6 years) from 7 centers: all patients were under 18 years old, underwent Gamma Knife radiosurgery, and had 12 or more months of clinical follow-up. Hemorrhage was the presenting symptom in 69% of patients. On multivariate analysis, hemorrhagic presentation was more common in females (OR 1.7), deep location AVMs (OR 3.2) and smaller volumes. Assuming all AVMs are congenital and has hemorrhage risk for the entire life of patients before presentation, the calculated hemorrhage rate before radiosurgery is 6.3% per year. Favorable outcomes after radiosurgery is defined as lack of hemorrhage, AVM obliteration (defined on MRI or angiogram), and lack of symptomatic radiation-induced changes. AVM obliteration was noted in 63% of patients, with favorable outcome achieved in 59%. In multivariate analysis, higher radiosurgery margin dose (>22Gy) and absence of prior embolization were associated with favorable outcome. Annual risk of re-hemorrhage after treatment was 1.4%. These reports provide information on the radiosurgery response of pediatric AVMs with important limitations. All included patients underwent radiosurgery, thus providing no information on AVM natural history; the majority of patients came from 2 centers and some authors disclosed financial relationships with the Gamma Knife manufacturer.