Object: Bilateral intimal thickening of the distal internal carotid arteries (ICAs) and the development of many collateral vessels in the base of the brain characterize moyamoya disease (MMD). Although the etiology of and the reason why MMD is limited to the major intracranial vessels remain unclear, flow dynamics, such as shear stress, may be related to its smooth-muscle cell migration. Therefore, this study was performed to determine the local hemodynamic factor, which concerns the predominance of specific anatomical sites, such as the distal ICA in the early stage and the proximal posterior cerebral artery (PCA) in the advanced stage of MMD.
Methods: The authors simulated the hemodynamics in the circle of Willis using computational models of 2D geometries of the distal ICA and PCA. A finite-element commercial package, automatic dynamics incremental nonlinear analysis (ADINA), was used to simulate blood flow in these arteries.
Results: Numerical results demonstrated that shear stress was relatively low at the ICA region. The distribution of shear stress was related to the predisposing area of MMD.
Conclusions: Diminished shear stress may promote stenosis of the distal ICA, which is a major pathological region in MMD.