Fistula components of brain arteriovenous malformations: angioarchitecture analysis and embolization prior to gamma-knife surgery.

BACKGROUND Gamma-knife surgery (GKS) is ineffective for high-flow arteriovenous fistula (AVF). The purpose of this study was to present the angioarchitecture of the AVF of brain arteriovenous malformation (BAVM) and report our experience of endovascular embolization of AVF component prior to GKS. METHODS In the past 10 years, a total of 523 BAVMs had been treated primarily by GKS. Among these, 10 patients with AVF components were identified and referred for embolization prior to GKS. Those patients underwent GKS within 4 weeks after embolization. We analyzed retrospectively the angioarchitecture of the AVFs of BAVMs, selection of embolic materials for embolization, and treatment outcomes. RESULTS The location of the AVFs was anterior (n = 7) or middle (n = 3) cerebral artery. Central and peripheral types of AVFs were found in seven and three patients, respectively. Nine AVFs were totally occluded by a single session of endovascular embolization, while one failed to be embolized because it was inaccessible to a microcatheter. Detachable coils (n = 6) or combination of liquid adhesives (n = 3) were selected to embolize the AVF. No significant periprocedural neurological complication was found. BAVMs were obliterated totally by subsequent GKS in six patients and partial occlusion was achieved in one, while three still awaited the effect of GKS. Mean imaging and clinical follow-up periods were 35 and 48 months, respectively. CONCLUSION Early detection of the central type of AVF of BAVM prior to GKS may be difficult because of its overlapping with feeder, nidus, and/or venous drains or it being overlooked. Peripheral-type AVFs were usually evident prior to GKS, particularly those with proximal dilated venous drains. Endovascular embolization is an effective modality for managing these AVFs, which may be treated by GKS ineffectively.