Reduction of Wall Shear Stress and Oscillatory Shear Index Following Endovascular Coiling in MCA Aneurysms: A Hemodynamic Study

This study evaluates the hemodynamic effects of endovascular coiling on middle cerebral artery (MCA) aneurysms in two age groups (20-39 and 60-69 years), focusing on flow-related parameters such as wall shear stress (WSS), pressure, time-averaged wall shear stress (AWSS), and oscillatory shear index (OSI). Computational fluid dynamics (CFD) simulations were conducted using age-specific pulsatile flow waveforms on patient-derived MCA aneurysm models. Computational fluid dynamics (CFD) simulations were performed using the incompressible Navier-Stokes equations with a Casson non-Newtonian blood model, rigid-wall assumption, and pulsatile inlet waveforms. The coil mass was modeled as a porous medium via the Kozeny-Carman permeability formulation. Two configurations were compared: non-endovascular coiling and post-endovascular coiling. Hemodynamic variables were assessed through contour plots and quantified in terms of maximum and mean values across the aneurysm wall. Endovascular coiling significantly reduced mean WSS (from ~6.7 Pa to ~2.9 Pa), mean AWSS (from ~1170 Pa to ~440 Pa), and maximum OSI (from 0.203-0.267 to 0.070-0.086) across both age groups. Contour analyses revealed substantial disruption of intra-aneurysmal vortices and oscillatory flow patterns post-coiling, especially at the dome and neck. Despite localized increases in maximum AWSS and pressure, the overall hemodynamic burden on the aneurysm wall was markedly reduced. Age-related differences were modest, with older individuals showing slightly elevated OSI and lower pressure values. Endovascular coiling provides effective hemodynamic stabilization in MCA aneurysms by suppressing deleterious flow patterns and shear-related stresses. The treatment is beneficial across age groups, supporting its clinical utility for mitigating aneurysm rupture risk. These findings may inform patient-specific treatment planning and long-term outcome assessment.