School of Mechanical Engineering, University of New South Wales, Library Rd, Kensington, NSW, 2052, Australia.
Department of Medical Imaging, John Hunter Hospital, Newcastle, NSW, Australia.
Fluids Barriers CNS. 2021 Feb 4;18(1):5. doi: 10.1186/s12987-021-00239-2.
It has been shown that idiopathic intracranial hypertension (IIH) in children is associated with cerebral hyperemia, which induces an increase in cerebral venous pressure. The current literature suggests venous pressure scales with blood flow in a linear fashion, however, a linear relationship would not raise the pressure high enough to induce IIH. There is, however, some evidence to suggest that this relationship could be quadratic in nature. The purpose of this paper is to characterize the relationship between cerebral blood flow and the pressure drop across the cerebral venous system.
10 CT venogram data sets were collected for this study, with 5 useable geometries created. Computational fluid dynamics (CFD) models were generated using these geometries, with 10 simulations conducted per patient. The flow rates tested ranged from 200 mL/min to 2000 mL/min. 3D pressure and velocity streamline distributions were created and analyzed for each CFD model, with pressure drops across the cerebral venous system determined. The effective and hydraulic diameters were determined at the superior sagittal sinus, transverse sinus and both proximal and distal sigmoid sinuses.
A quadratic relationship between blood flow and sinus pressure was found, with correlations of 0.99 or above in all five patients. The presence of vortical blood flow was found to explain this trend, with fluid curl and pressure drop correlations being above 0.97. This suggests that the presence of high blood flow should be considered in the diagnostic workup of IIH.
The cerebral venous sinus blood flow and pressure response relationship are quadratic in nature, with the major cause of this being the degree of rotation induced in the flow. The elevated blood flow found in children with IIH can explain the increased ICP that is found, secondary to the increase in venous pressure that develops.
已经表明，儿童特发性颅内高压（IIH）与脑充血有关，这会导致脑静脉压升高。目前的文献表明，静脉压力与血流量呈线性关系，但线性关系不会使压力升高到足以引起 IIH 的程度。然而，有一些证据表明这种关系可能是二次的。本文的目的是描述脑血流量与脑静脉系统压降之间的关系。
本研究共收集了 10 例 CT 静脉造影数据集，其中创建了 5 个可用几何图形。使用这些几何图形生成计算流体动力学（CFD）模型，每个患者进行 10 次模拟。测试的流速范围从 200 毫升/分钟到 2000 毫升/分钟。为每个 CFD 模型创建并分析了三维压力和速度流线分布，确定了脑静脉系统的压降。确定了上矢状窦、横窦以及近端和远端乙状窦的有效和水力直径。
发现血流量与窦压之间存在二次关系，所有 5 例患者的相关性均在 0.99 或以上。发现涡流血流存在解释了这种趋势，流体卷曲和压降相关性均在 0.97 以上。这表明在 IIH 的诊断中应考虑高血流量的存在。
脑静脉窦血流量和压力响应关系呈二次关系，主要原因是流引起的旋转程度。在 IIH 儿童中发现的血流量升高可以解释继发于发展中的静脉压升高而导致的 ICP 升高。
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