Object. This study was undertaken to assess the efficacy and safety of gamma knife radiosurgery (GKS) for the treatment of arteriovenous malformations (AVMs) located within the brainstem.
Methods. The results of GKS performed in 87 patients with brainstem AVMs at two centers with experienced physicians are reviewed. The mean patient age was 37 years and the population included 19 children. The male/female ratio was 56:31. The malformation was located in the upper brainstem in 52 patients. Seventy-four percent of the patients had suffered a hemorrhage before GKS. For 70% of the patients no other treatment had been proposed before GKS. The mean AVM volume was 1.3 cm3. The lesions were treated with one to eight isocenters, with a margin dose ranging between 11.5 Gy and 30 Gy. The mean clinical follow-up period was 3.2 years. Ninety-five percent of the patients improved or remained neurologically stable. Rebleeding occurred in three patients at 3, 6, and 16 months, respectively, after GKS. Two patients in whom rebleeding occured recovered, and one died. The AVM obliteration rate was 63% at 2 years and 73% at 3 years after GKS. A second GKS was performed in six patients in whom only partial obliteration was demonstrated on angiography 3 years after the first procedure.
Conclusions. Gamma knife radiosurgery may be a valuable first-choice therapy for the treatment of AVMs located within the brainstem.