Pathomechanistic role of central venous pressure in idiopathic intracranial hypertension

OBJECTIVE The presence of dural venous stenosis in idiopathic intracranial hypertension (IIH) is well recognized. However, the complex interplay between intracranial and extracranial factors contributing to pathological intracranial venous congestion remains poorly understood. In this study, the authors explored venous sinus characteristics in cohorts with elevated central venous pressure (eCVP; ≥ 8 mm Hg) and normal CVP (nCVP; < 8 mm Hg). METHODS The authors retrospectively reviewed medical records for adult patients who underwent invasive venography with manometry for a suspected or confirmed diagnosis of IIH between January 2017 and December 2024. Venous dimensions and pressure profiles were compared between eCVP and nCVP cohorts. RESULTS Ninety-eight patients had recorded CVP measurements. The eCVP group (n = 46) exhibited elevated pressures throughout the venous sinuses compared with the nCVP group (n = 52), but opening pressures (OPs), venous sinus dimensions, and pressure gradients did not differ. Post hoc receiver operating characteristic curve analysis identified an internal jugular vein (IJV) pressure cutoff of ≥ 10.5 mm Hg as predictive of eCVP (sensitivity 65.2%, specificity 88.5%, area under the curve 0.835). Applying this threshold, all 268 patients who underwent cerebral venography with manometry were stratified into having an eCVP or eCVP-like effect (n = 96; IJV ≥ 10.5 mm Hg) versus nCVP-like effect (n = 172; IJV < 10.5 mm Hg) on intracranial venous sinus hemodynamics for a strengthened power analysis. Compared with patients with an nCVP-like effect, patients with an eCVP or eCVP-like effect demonstrated higher lumbar puncture OPs (p = 0.05) and narrower sagittal, transverse, and sigmoid sinuses (all p < 0.05), along with the previously observed elevation of venous pressures throughout the sinuses. Furthermore, scatterplots evaluating the relationship between venous sinus dimensions and pressure gradients, stratified by eCVP and nCVP, revealed delayed onset of pressure gradients with increasing OP, higher pressure gradients, and narrower sinus diameters in patients with eCVP compared with patients with nCVP at similar OPs suggested increased dural venous wall compliance. CONCLUSIONS The authors demonstrate the variability in venous sinus dimensions and pressure gradient profiles with increasing OP, stratified by eCVP versus nCVP. Although eCVP initially protected against gradient development, it ultimately resulted in higher venous pressures, which hindered CSF resorption to a greater extent than nCVP, thereby increasing OP to a greater extent, which eventually resulted in greater stenosis and a higher gradient before plateauing. Patients with eCVP demonstrated more compliant dural venous sinus walls, which could influence long-term effectiveness of stenting and chances of progressive adjacent venous sinus stenosis.