• Tetsuo Sasaki, Yukinari Kakizawa, Masato Yoshino, Yasuhiro Fujii, Ikumi Yoroi, Yozo Ichikawa, Tetsuyoshi Horiuchi, and Kazuhiro Hongo.
• Department of Neurosurgery, Shinshu University School of Medicine, Matsumoto, Japan.
• Neurosurgery. 2019 Jul 1; 85 (1): E31-E39.

BackgroundHemodynamic factors, especially wall shear stress (WSS), are generally thought to play an important role in intracranial aneurysm (IA) formation. IAs frequently occur at bifurcation apices, where the vessels are exposed to the impact of WSS.ObjectiveTo elucidate the relationship between bifurcation geometry and WSS for IA formation.MethodsTwenty-one bifurcation models varying in branch angles and branch diameters were made with 3-dimensional computer-aided design software. In all models, the value of maximum WSS (WSSMAX), the area of high WSS (AREA), and the magnitude of wall shear force over AREA ($| {{{\vec{F}}_w}} |$) were investigated by the steady-flow simulation of computational fluid dynamics.ResultsOn the basis of statistical analysis, WSSMAX tended to be high when the bifurcation angle and/or branch diameter was small. AREA and $| {{{\vec{F}}_w}} |$ significantly increase as the bifurcation and/or the branch angle became larger.ConclusionThe magnitude of WSS strongly correlated with bifurcation geometry. In addition to high WSS, AREA and $| {{{\vec{F}}_w}} |$ were thought to affect IA formation. Observed bifurcation geometry may predict IA formation. Large branch angles and small branch may increase the risk of IA formation.Copyright © 2018 by the Congress of Neurological Surgeons.

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