Flow-based simulation in transverse sinus stenosis pre- and post-stenting: pressure prediction accuracy, hemodynamic complexity, and relationship to pulsatile tinnitus.

BACKGROUND: The proximity of transverse sinus stenosis (TSS) to inner ear structures and the temporal bone makes it a substantial cause of pulsatile tinnitus (PT). Treatment typically involves venous sinus stenting. This study investigates the hemodynamic stressors in TSS patients with PT along the pulse-transmitting temporal bone area and evaluates its treatment effects.

METHODS: Four patients with idiopathic intracranial hypertension, PT, and TSS, and four control patients were imaged using MR venography (MRV) and flat panel CT (FP-CT). Patient-specific blood flow simulations were conducted using boundary conditions based on quantitative MR angiography before and after VSS. Catheter-based trans-stenotic pressure gradient measurements were used to validate the simulation results.

RESULTS: The prediction of pressure gradients was close to catheter-based measurements using FP-CT-based segmentations (absolute deviation of 0.35 mm Hg) and is superior to MRV-based reconstructions (absolute deviation of 6.9 mm Hg). In TSS patients, the sinus temporal bone contact areas revealed notably higher time-averaged wall shear stress by 47±22% and velocity values by 41±18% compared with the sinus brain side. The relative residence time decreased by 57±58%. After stenting, the hemodynamic parameters dropped at the temporal side and throughout the sigmoid sinus. Almost all control patient hemodynamics remained lower than post-interventional results.

CONCLUSION: Our simulations based on patient-specific flows highly predicts pressure gradients across the stenosis. Flow conditions in TSS reveal flow jet formation and high shear rates at the temporal bone, potentially causing sound transmission. The treatment reduces these stressors, demonstrating its targeted therapeutic effect.