Interactive effect of hemodynamics in transverse sigmoid sinus and bone morphology on venous pulsatile tinnitus: a fourdimensional (4D) flow magnetic resonance imaging (MRI) study

Background: The hemodynamic pathogenesis of venous pulsatile tinnitus (VPT) is still unclear. This study aimed to explore the mechanism of bone morphology and hemodynamic changes in transverse sigmoid sinus (TSS) on VPT patients.<br /> Methods: 49 patients with unilateral VPT, 26 patients with subjective tinnitus and 36 healthy controls were included in this retrospective clinical trial. Four-dimensional (4D) flow magnetic resonance imaging (MRI) was used to evaluate the hemodynamics of the TSS. High-resolution computed tomography was used to assess the perivenous bone structures. All images were independently assessed for each participant by two trained neuroradiologists. Kolmogorov-Smirnov test was used to determine the normal distribution of the data. Chi-square test and nonparametric test were used to compare classified or continuous variables. Stepwise linear regression and mediation effect analysis was used to explore the relationship between bone dehiscence (BD), hemodynamic factors and VPT symptoms.<br /> Results: Peak velocity (P=0.001) and maximum energy loss (P=0.041) in VPT group were risk factors for the severity of tinnitus. Energy loss [indirect effect =0.692, P<0.005, 95% confidence interval (CI): 0.201- 1.377] and peak velocity (indirect effect =0.899, P<0.005, 95% CI: 0.406-1.582) demonstrated the complete mediation effect between the BD and VPT. BD showed a complete mediation effect between the wall shear stress (WSS) and VPT (indirect effect =15.181, P<0.005, 95% CI: 3.448-35.493). Conclusions: Cross-talk between the hemodynamic changes of TSS and BD can regulate the VPT symptoms. This type of analysis might be helpful in establishing the possible occurrence and development mechanism of the hemodynamics and bone morphology of the VPT.