Association of Basilar Bifurcation Aneurysms With Age, Sex, and Bifurcation Geometry.

BACKGROUND AND PURPOSE: Basilar artery (BA) bifurcation aneurysms are common, but the correlation between BA bifurcation morphology and aneurysm formation remains to be established. Our purpose was to determine the association of BA bifurcation aneurysms with patient age, sex, bifurcation angle, and branch diameter. METHODS: Three-dimensional angiographic data of 195 patients were used, including 59 patients with BA bifurcation aneurysms and 136 control subjects. The angles formed between left and right posterior cerebral arteries (φ1) and between posterior cerebral artery and BA (the smaller angle defined as φ2 and the larger one as φ3), arterial diameters, and BA bifurcation aneurysm geometric characters were examined. RESULTS: Women of 40 to 70 years of age are more vulnerable to BA bifurcation aneurysm formation than men. The φ1 bifurcation angle significantly increased (P<0.0001), whereas both φ2 and φ3 angles significantly decreased (P<0.0001 and P=0.09, respectively) with increase of patients' age. Statistically significant (P<0.0001 and P=0.0002, respectively) positive correlations were observed between BA bifurcation branch diameter and aneurysm size. The φ1 angle was significantly (P<0.0001) wider in patients harboring BA bifurcation aneurysms than the control, whereas φ2 and φ3 angles in aneurysm group were significantly smaller than those in the control group (P<0.0001). The BA bifurcation aneurysms were mostly deviated toward the smaller φ2 angle side between φ2 and φ3 angles and deviated toward the smaller-diameter daughter posterior cerebral artery branch. CONCLUSIONS: BA bifurcation aneurysms are significantly associated with patients' age, female sex, wider bifurcation angles, and smaller vascular diameter at the BA bifurcation.

Presence of Anterior Communicating Artery Aneurysm Is Associated With Age, Bifurcation Angle, and Vessel Diameter.

BACKGROUND AND PURPOSE: The anterior communicating artery (Acom) aneurysm is the most complex in all cerebral aneurysms, and wider vascular bifurcation angles are considered to be associated with aneurysm formation. The objective of this study was to investigate association of the Acom aneurysm formation with patient age and vascular bifurcation morphology. METHODS: Three-dimensional angiographic data of 665 patients were used in this study, including 160 patients with Acom aneurysms, 66 with non-Acom aneurysms, and 439 control subjects with no aneurysms. The anterior cerebral artery bifurcation angle (Acom/A2 angle), arterial diameters, and Acom aneurysm geometric characters were examined. RESULTS: Women of 50 to 70 years were more vulnerable to Acom aneurysm formation than men. The Acom/A2 bifurcation angle was significantly increased (P<0.0001) with increase of patient age. The size of the Acom aneurysm dome and neck was statistically positively correlated with the diameter of the Acom, A1 and A2 segments (P<0.0001). The Acom/A2 bifurcation angle was significantly (P<0.0001) wider in patients with than without Acom aneurysms, whereas the A1/A2 angle was significantly smaller in patients with than without Acom aneurysms (P<0.0001). The Acom aneurysms at the bifurcation apex mostly deviated toward the smaller angle formed between the parent A1 and branches and toward the daughter artery with a smaller diameter. The Acom aneurysms were located mostly on the dominant anterior cerebral artery. CONCLUSIONS: The presence of Acom aneurysm is significantly associated with patient age, wider angles of the anterior cerebral artery bifurcation, and smaller vascular diameter of the anterior communicating complex.