Association of Basilar Bifurcation Aneurysms With Age, Sex, and Bifurcation Geometry (Publication with Expression of Concern. See vol. 51, 2020)

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 (1) and between posterior cerebral artery and BA (the smaller angle defined as 2 and the larger one as phi 3), 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 phi 1 bifurcation angle significantly increased (P<0.0001), whereas both phi 2 and phi 3 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 phi 1 angle was significantly (P<0.0001) wider in patients harboring BA bifurcation aneurysms than the control, whereas phi 2 and phi 3 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 phi 2 angle side between phi 2 and phi 3 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.