Abstract
BackgroundPreviously published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results. Our study analysed the involvement of the combination of high wall shear stress (WSS) and a positive WSS gradient (WSSG) in IA formation.MethodsWe designed a case-control study with a selection of 38 patients with an unruptured middle cerebral artery (MCA) aneurysm and 39 non-aneurysmal controls to determine the involvement of WSS, oscillatory shear index (OSI), the WSSG and its absolute value (absWSSG) in aneurysm formation based on patient-specific CFD simulations using velocity profiles obtained from transcranial colour-coded sonography.ResultsAmong the analysed parameters, only the WSSG had significantly higher values compared to the controls (11.05 vs − 14.76 [Pa/mm], P = 0.020). The WSS, absWSSG and OSI values were not significantly different between the analysed groups. Logistic regression analysis identified WSS and WSSG as significant co-predictors for MCA aneurysm formation, but only the WSSG turned out to be a significant independent prognosticator (OR: 1.009; 95% CI: 1.001–1.017; P = 0.025). Significantly more patients (23/38) in the case group had haemodynamic regions of high WSS combined with a positive WSSG near the bifurcation apex, while in the control group, high WSS was usually accompanied by a negative WSSG (14/39). From the analysis of the ROC curve for WSSG, the area under the curve (AUC) was 0.654, with the optimal cut-off value −0.37 Pa/mm. The largest AUC was recognised for combined WSS and WSSG (AUC = 0.671). Our data confirmed that aneurysms tend to form near the bifurcation apices in regions of high WSS values accompanied by positive WSSG.ConclusionsThe development of IAs is determined by an independent effect of haemodynamic factors. High WSS impacts MCA aneurysm formation, while a positive WSSG mainly promotes this process.
Highlights
Published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results
The main findings of this study are: (1) cerebral aneurysm development might be an independent effect of haemodynamic factors and (2) aneurysms form near the bifurcation apices in regions of high wall shear stress (WSS) values accompanied by positive WSS gradient (WSSG)
This study demonstrated that the development of cerebral aneurysms might be an independent effect of haemodynamic factors
Summary
Published computational fluid dynamics (CFD) studies regarding intracranial aneurysm (IA) formation present conflicting results. Intracranial aneurysms (IAs) are defined as pathological dilations of intracranial arteries caused by a weakness within the arterial wall. They are a relatively common disease with a worldwide prevalence of approximately 3% [1]. Published data have shown that the vascular segments mentioned above are affected by complex haemodynamic forces, such as: wall shear stress (WSS), the wall shear stress gradient (WSSG), and temporal fluctuations in WSS [4, 5, 9,10,11,12,13,14,15,16]
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