The Effect of Concurrent Arterial Aneurysms on the Risk of Hemorrhagic Presentation in Brain Arteriovenous Malformations
Background and Purpose: To assess the effect of concurrent arterial aneurysms on the risk of hemorrhagic presentation in brain arteriovenous malformations (AVMs). Methods: The 463 consecutive, prospectively enrolled patients from the New York AVM Databank were analyzed. Concurrent arterial aneurysms on brain angiography were classified as (1) flow-related feeding artery aneurysms, (2) intranidal aneurysms, and (3) aneurysms unrelated to blood flow to the AVM. Clinical presentation (diagnostic event) was categorized as (1) intracranial hemorrhage proven by imaging or (2) non-hemorrhagic presentation. Univariate and multivariate statistical models were applied to test the effect of age, gender, AVM size, venous drainage pattern, and the three different types of aneurysms on the risk of AVM hemorrhage at initial presentation. Results: Arterial aneurysms were found in 117 (25%) AVM patients. In 93 cases, a single aneurysm type was found (54 had feeding artery aneurysms, 21showed intranidal aneurysms, 18 had unrelated aneurysms), 24 patients had more than one aneurysm type. Overall, 204 (44%) patients presented with hemorrhage. Concurrent arterial aneurysms were significantly more frequent in patients with incident AVM hemorrhage (34%) as compared to those without hemorrhage (18%, p=0.001). In the multivariate model an independent effect for flow-related aneurysms (OR 2.1 , 95% CI: 1.2 to 3.8) on hemorrhagic AVM presentation was found. No effect was seen for intranidal and unrelated aneurysms. The attributable risk of incident hemorrhage in AVM patients harbouring flow-related aneurysms is 0.059 (95% CI: 0.01 to 0.105). Conclusions: The findings suggest that flow-related arterial aneurysms are an independent determinant for increased risk of incident AVM hemorrhage.