Proposal of Classification of Aneurysms Coexisting with AVM and Possible Treatment Strategies.

AIM To describe the classification of aneurysms coexisting with arteriovenous malformations (AVMs) and their endovascular treatment. MATERIAL AND METHODS Based on the basis of radiological findings and clinical features, 59 aneurysms coexisting with AVMs were classified into four different types: intranidal, flow-related (proximal and distal), and unrelated. These aneurysms were treated by endovascular techniques with or without AVM embolization. Clinical outcome was assessed using the modified Rankin Scale (mRS). RESULTS 59 aneurysms coexisting with AVMs were found in 39 patients. There were 11 unrelated aneurysms, 18 proximal flow-related aneurysms, 11 distal flow-related aneurysms and 19 intranidal aneurysms. In the 11 unrelated aneurysms, 4 were caused subarachnoid hemorrhage. In 11 distal flow-related aneurysms near the AVM, 7 caused a major hemorrhage. Six of the 19 intranidal aneurysms presented with hemorrhage. In contrast, only 3 of the 14 proximal flow-related aneurysms on major feeding arteries caused hemorrhage. CONCLUSION Aneurysms coexisting with AVMs could be classified into four types and this classification may provide a rationale for endovascular treatment.