Morphologic Change of Flow-Related Aneurysms in Brain Arteriovenous Malformations after Stereotactic Radiosurgery

Abstract

BACKGROUND AND PURPOSE:The natural history of flow-related aneurysms after obliteration of brain arteriovenous malformations is poorly understood. The purpose of this study was to evaluate the angioarchitecture and morphologic change in flow-related aneurysms after gamma knife surgery of brain arteriovenous malformations. MATERIALS AND METHODS:During a 12-year period, 823 patients with brain arteriovenous malformations underwent gamma knife surgery at our institution with complete peritherapeutic angiographic evaluation. From this population, a series of 72 patients (8.8%) with 111 flow-related aneurysms were enrolled (1.5 aneurysms per patient). There were 43 men and 29 women; ages ranged from 18 to 72 years (mean, 43 years). The morphologic change of flow-related aneurysms was longitudinally evaluated before and after obliteration of brain arteriovenous malformations. After gamma knife surgery, angiographic follow-up varied from 26 to 130 months (mean, 58 months). RESULTS:All flow-related aneurysms were small (mean, 4.1 mm; range, 2-9 mm). There were 72 proximal flow-related aneurysms (mean size, 4.3 mm) and 39 distal flow-related aneurysms (mean size, 3.7 mm). Spontaneous thrombosis occurred more frequently in distal flow-related aneurysms than in proximal flow-related aneurysms (P Ͻ .001). Smaller flow-related aneurysms (Ͻ5 mm) tended to spontaneously occlude after obliteration of brain arteriovenous malformations (P ϭ .036). Two patients had ruptures of proximal flow-related aneurysms at 27-and 54-month follow-ups, respectively. CONCLUSIONS:Spontaneous thrombosis occurred more frequently in distal flow-related aneurysms due to occlusion or normalization of distal feeders. Smaller flow-related aneurysms also tended to spontaneously thrombose after obliteration of brain arteriovenous malformations. The rate of flow-related aneurysm rupture in our series was similar to that of natural intradural aneurysms. ABBREVIATIONS: ACA ϭ anterior cerebral artery; BAVM ϭ brain arteriovenous malformation; FA ϭ flow-related aneurysm; GKS ϭ gamma knife surgery

Endovascular treatment for the flow-related aneurysm originating from an anterior inferior cerebellar artery supplying the cerebellar arteriovenous malformation

“…If the unruptured AICA aneurysm is far from the AVM nidus, a wait-and see regimen can be adopted, as some unruptured aneurysms could experience spontaneous thrombosis after obliteration of the AVM. 10,15 But, the remodeling and regression process of aneurysm goes slowly after AVM elimination. Catastrophic rupture should be considered for irregular and big feeding artery aneurysm, due to the increase in feeding artery pressure following endovascular embolization of the AVM.…”