Elsevier

Gender Medicine

Volume 7, Issue 2, April 2010, Pages 149-155
Gender Medicine

Sex differences in intracranial arterial bifurcations

https://doi.org/10.1016/j.genm.2010.03.003Get rights and content

Abstract

Background: Subarachnoid hemorrhage (SAH) is a serious condition, occurring more frequently in females than in males. SAH is mainly caused by rupture of an intracranial aneurysm, which 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 systemic factors (hormonal influences and intrinsic wall weakness); however, the uneven sex distribution of intracranial aneurysms suggests a possible physiologic factor—a local sex difference in the intracranial arteries.

Objective: The aim of this study was to explore sex variation in the bifurcation anatomy of the middle cerebral artery (MCA) and internal carotid artery (ICA), and the subsequent hemodynamic impact.

Methods: Vessel radii and bifurcation angles were measured in patients with MCA and ICA bifurcations. Data from a previously published study of 55 patients undergoing diagnostic cerebral digital subtraction angiography at Dalcross Private Hospital in Sydney, Australia, between 2002 and 2003, were available for analysis. 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 vessel radii and bifurcation angles of 47 MCA and 52 ICA bifurcations in 49 patients (32 females, 17 males; mean age, 53 years; age range, 14–86 years) were measured. Statistically significant sex differences were found in vessel diameter (males larger than females; P < 0.05), but not in bifurcation angle. Computational fluid dynamics simulations revealed higher wall shear stress in the female MCA (19%) and ICA (50%) bifurcations compared with the male bifurcations.

Conclusions: This study of MCA and ICA bifurcations in female and male patients suggests that sex differences in vessel size and blood flow velocity result in higher hemodynamic forces acting on the vessel wall in females. This new hypothesis may partly explain why intracranial aneurysms and SAH are more likely to occur in females than in males.

References (37)

  • CN Mhurchu et al.

    Hormonal factors and risk of aneurysmal Subarachnoid hemorrhage: An international populationbased, case-control study

    Stroke

    (2001)
  • SC Johnston et al.

    Oral contraceptives and the risk of subarachnoid hemorrhage: A meta-analysis

    Neurology

    (1998)
  • NK de Rooij et al.

    Incidence of subarachnoid haemorrhage: A systematic review with emphasis on region, age, gender and time trends

    J Neurol Neurosurg Psychiatry

    (2007)
  • WT Longstreth et al.

    Subarachnoid hemorrhage and hormonal factors in women. A population-based case-control study

    Ann Intern Med

    (1994)
  • M Falkeborn et al.

    Hormone replacement therapy and the risk of stroke. Follow-up of a population-based cohort in Sweden

    Arch Intern Med

    (1993)
  • T Horiuchi et al.

    Sex-related differences in patients treated surgically for aneurysmal subarachnoid hemorrhage

    Neurol Med Chir (Tokyo)

    (2006)
  • T Ingebrigtsen et al.

    Bifurcation geometry and the presence of cerebral artery aneurysms

    J Neurosurg

    (2004)
  • J Krejza et al.

    Age and sex variability and normal reference values for the V(MCA)N(ICA) index

    AJNR Am J Neuroradiol

    (2005)
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