Case Report: Unveiling segmental hemodynamic heterogeneity in internal jugular vein stenosis: a patient-specific CFD analysis.

While non-thrombotic internal jugular vein stenosis (IJVS), predominantly from extrinsic compression, is increasingly linked to cerebral venous outflow insufficiency, its segment-specific pathophysiology remains unclear. Given the distinct J1-J3 anatomy of the internal jugular vein, segment-based characterization may aid management. We retrospectively analyzed five patients with non-thrombotic IJVS affecting different segments and etiologies. Clinical features, segment involvement, and lesion morphology were recorded. Patient-specific hemodynamics were modeled with computational fluid dynamics (CFD) from head-neck CT venography (CTV) using identical boundary conditions for cross-case comparison. All cases showed trans-stenotic pressure gradients that increased with stenosis severity. Elevated wall shear stress localized to the stenosis, with high-velocity jets within the narrowed segment and downstream vortices in post-stenotic regions. J3 stenoses from C1 transverse process and/or styloid compression improved after decompression, with better hemodynamic metrics, venous morphology, and symptoms. J1-J2 stenoses were mainly due to soft-tissue or arterial compression; feasible interventions were limited and conservative care yielded modest benefit. IJVS demonstrates segment-specific morphological and hemodynamic patterns. Patient-specific CFD derived from CTV quantitatively characterizes these abnormalities and may inform treatment selection and prognosis, although validation in larger cohorts is warranted.