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 P P =0.09, respectively) with increase of patients’ age. Statistically significant ( P P =0.0002, respectively) positive correlations were observed between BA bifurcation branch diameter and aneurysm size. The φ1 angle was significantly ( P P Conclusions— BA bifurcation aneurysms are significantly associated with patients’ age, female sex, wider bifurcation angles, and smaller vascular diameter at the BA bifurcation.