Impact of microvascular decompression on wall shear stress in responsible arteries in trigeminal neuralgia and hemifacial spasm.

Microvascular decompression (MVD) has proven efficacy in trigeminal neuralgia (TN) and hemifacial spasm (HFS). This study utilized computational fluid dynamics (CFD) to investigate the impact of MVD on wall shear stress (WSS) of responsible arteries (RAs) at the neurovascular contact (NVC). A total of 21 cases (10 TN, 11 HFS) were analyzed, involving RAs at NVC validated through intraoperative photographs. Hemodynamic parameters (WSS, vessel diameter, flow rate, pressure drop) was calculated using CFD for the RAs based on 3D silent-magnetic resonance angiograms. The NVC was segmented into NVC-proximal, NVC-site, and NVC-distal portions using simulated 3D CFD images that correlated with surgical observations. WSS ratios of NVC-site to NVC-proximal (NVC-site/proximal) was calculated both before and after MVD. Prior to MVD, WSS in the RA at the NVC displayed a peaked curve with a maximum at NVC-site; however, post MVD, it presented a smooth curve without peaks. The WSS ratio exhibited a significant decrease after MVD. The impact of MVD on WSS of RAs at NVC was evaluated in both TN and HFS cases. Analyzing the hemodynamics of RAs through CFD and identifying WSS peaks at NVC portions before MVD provided a more detailed and localized understanding of the morphologically depicted NVC.