Arterial Pulsation-driven Cerebrospinal Fluid Flow in the Perivascular Space: A Computational Model

Abstract

This study was conducted to determine whether local arterial pulsations are sufficient to cause cerebrospinal fluid (CSF) flow along perivascular spaces (PVS) within the spinal cord. A theoretical model of the perivascular space surrounding a "typical" small artery was analysed using computational fluid dynamics. Systolic pulsations were modelled as travelling waves on the arterial wall. The effects of wave geometry and variable pressure conditions on fluid flow were investigated. Arterial pulsations induce fluid movement in the PVS in the direction of arterial wave travel. Perivascular flow continues even in the presence of adverse pressure gradients of a few kilopascals. Flow rates are greater with increasing pulse wave velocities and arterial deformation, as both an absolute amplitude and as a proportion of the PVS. The model suggests that arterial pulsations are sufficient to cause fluid flow in the perivascular space even against modest adverse pressure gradients. Local increases in flow in this perivascular pumping mechanism or reduction in outflow may be important in the etiology of syringomyelia.

Tensile radial stress in the spinal cord related to arachnoiditis or tethering: a numerical model

“…Our hypothesis does not directly address this issue. Thinking more of transiently raised SAS pressure than lowered cord tissue pressure, Bilston et al [3] have postulated that flow from the SAS to the interior of the cord tissue may be encouraged by pulsatile distension of the microscopic arteries around which the perivascular spaces provide a channel for CSF transport into the cord.…”

Fluid mechanics in the perivascular space

“…When the ratio of the wavelength to the half-width of the channel is assumed to be large, lubrication approximations can be applied and analytical solutions can be obtained in some circumstances. Alternatively, computational fluid dynamics can be used to directly solve the Navier-Stokes equations with complex boundary geometry and boundary conditions and with arbitrary peristaltic waveforms (Bilston et al, 2003).…”

Direct-trauma model of posttraumatic syringomyelia with a computer-controlled motorized spinal cord impactor

“…2,45,46 Lesions at the cervicothoracic region are preferable because human posttraumatic syringomyelia commonly affects the cervical cord. The benefits of the impact model are the more precise and accurate delivery of a designated force without previous contact with the spinal cord and the ability to measure the force and displacement of the impact using sensors within the impactor tip.…”

“…[1][2][3][4]8,10 Mechanical models that aim to replicate the spinal cord, syrinx cavity, and stenosis within the subarachnoid space and enable pressure measurements of CSF waveforms have also been developed. 22,23 The advantages of computational and mechanical models are that they reduce the need for animals and can evaluate whether a hypothesis is biomechanically feasible.…”