AuthorsH. Lindekle, iv, K. Valen-Sendstad, M. K. Morgan, K. Mardal, K. Faulder, J. Magnus, K. Waterloo, B. Romner and T. Ingebrigtsen
TitleSex Differences in Intracranial Arterial Bifurcations
AfilliationScientific Computing, , Scientific Computing
Project(s)Center for Biomedical Computing (SFF)
Publication TypeJournal Article
Year of Publication2010
JournalGender Medicine
PublisherGend Med

Background: Subarachnoid hemorrhage (SAH) is a serious condition, occurring 50-70% more frequently in females than males. SAH is mainly caused by rupture of an intracranial aneurysm. An intracranial aneurysm is formed by localized dilation of the intracranial arterial vessel wall, usually at the apex of the arterial bifurcation. The female preponderance is usually explained by systemical factors (hormonal influences and intrinsic wall weakness). Objective: To explore any sex variation in the bifurcation anatomy of the MCA and ICA, and the subsequent hemodynamic impact. Methods: We measured vessel radii and bifurcation angles in 47 middle cerebral artery (MCA) and 52 internal carotid artery (ICA) bifurcations in 49 patients (32 females and 17 males). The measurements were used to create idealized, averaged bifurcations of the MCA and ICA for females and males. Computational fluid dynamics simulations were performed to calculate hemodynamic forces in the models. Results: The measurements showed statistically significant sex differences in vessel diameter (men larger than females), but not in bifurcation angles. Computational fluid dynamics simulations showed higher wall shear stress in the female MCA bifurcation (19 %) and ICA bifurcation (50 %) compared with the male bifurcations. Conclusions: The present study suggests that sex differences in vessel size and blood flow velocity result in higher hemodynamic forces acting upon the female vessel wall. This is a new hypothesis that may partially explain why intracranial aneurysms and SAH are more likely to occur in females than males.