Computational Modeling of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension

Abstract

Background and Purpose Idiopathic intracranial hypertension has been associated with dural venous sinus stenosis in some patients, but the hemodynamic environment of the dural venous sinuses has not been quantitatively described. Here, we present the first such computational fluid dynamics model using patient-specific blood pressure measurements. Materials and Methods Six patients with idiopathic intracranial hypertension and at least one stenosis or atresia at the transverse-sigmoid sinus junction underwent MRV followed by cerebral venography and manometry throughout the dural venous sinuses. Patient-specific computational fluid dynamics models were created using MRV anatomy, with venous pressure measurements as boundary conditions. Blood flow and wall shear stress were calculated for each patient. Results Computational models of dural venous sinuses were successfully reconstructed in all six patients with patient-specific boundary conditions. Three patients demonstrated a pathologic pressure gradient (≥ 8 mm Hg) across four dural venous sinus stenoses. Small sample size precludes statistical comparisons, but average overall flow throughout the dural venous sinuses of patients with pathologic pressure gradients was higher than in those without (1041.00 ± 506.52 vs. 358.00 ± 190.95 mL/min). Wall shear stress was also higher across stenoses in patients with pathologic pressure gradients (37.66 ± 48.39 vs 7.02 ± 13.60 Pa). Conclusion The hemodynamic environment of the dural venous sinuses can be computationally modeled using patient-specific anatomy and physiological measurements in patients with idiopathic intracranial hypertension. There was substantially higher blood flow and wall shear stress in patients with pathological pressure gradients.

Spatial distribution of flow and oxygenation in the cerebral venous drainage system

“…For instance, based on venous flow patterns one might be able to predict the occurrence of venous stroke in patients with venous thrombosis . Or, hydrocephalus patients with hemodynamically significant venous stenosis may be helped with stent placement . Venous flow measurements may help to unravel hydrocephalus, and regional venous flow measurements may help in the understanding of the pathophysiology of traumatic brain injury …”

“…2 Or, hydrocephalus patients with hemodynamically significant venous stenosis may be helped with stent placement. 3 Venous flow measurements may help to unravel hydrocephalus, 37 and regional venous flow measurements may help in the understanding of the pathophysiology of traumatic brain injury. 38 The strength of this study is that we applied relatively simple measurements, TRUST MRI and PC MRI, to obtain information about venous oxygenation and flow distribution.…”

“…In patients with venous thrombosis, venous flow, or the lack thereof, as well as the identification of collateral pathways, may help to depict those patients at risk of developing a venous stroke . Venous flow assessment in patients with idiopathic intracranial hypertension and dural venous sinus stenosis may be used to detect pathological cases where endovascular stent placement could be considered . In patients with hydrocephalus, the known interdependence of cerebrospinal fluid flow and venous blood flow may help in the assessment and therapy of these patients or could provide insight into the pathophysiology of hydrocephalus .…”

“…2 Venous flow assessment in patients with idiopathic intracranial hypertension and dural venous sinus stenosis may be used to detect pathological cases where endovascular stent placement could be considered. 3 In patients with hydrocephalus, the known interdependence of cerebrospinal fluid flow and venous blood flow may help in the assessment and therapy of these patients or could provide insight into the pathophysiology of hydrocephalus. 4 Similarly, venous blood flow assessment may help to investigate the proposed hypothesis of "venous insufficiency" in multiple sclerosis.…”

Men Are from Mars, Idiopathic Intracranial Hypertension Is from Venous: The Role of Venous Sinus Stenosis and Stenting in Idiopathic Intracranial Hypertension

“…21 The appropriate cut-off has not been established to determine which patients are appropriate candidates for stenting, although most interventionalists have used a minimum TSG of 4 to 10 mm Hg. 6,[22][23][24][25][26] Some groups measure the TSG before and after lumbar puncture and do not proceed with stenting if the TSG resolves (suggesting an extrinsic stenosis), believing that only intrinsic stenosis plays a causative role in the disease. However, the positive feedback loop theory discussed earlier and evidence demonstrating efficacy of stenting in patients with both intrinsic and extrinsic stenosis (see later) support consideration of the procedure in both cases.…”