Investigating cerebral oedema using poroelasticity

John C Vardakis,Dean Chou,Brett J Tully,Chang C Hung,Tsong H Lee,Po-Hsiang Tsui,Yiannis Ventikos

doi:10.1016/j.medengphy.2015.09.006

Abstract

Cerebral oedema can be classified as the tangible swelling produced by expansion of the interstitial fluid volume. Hydrocephalus can be succinctly described as the abnormal accumulation of cerebrospinal fluid (CSF) within the brain which ultimately leads to oedema within specific sites of parenchymal tissue. Using hydrocephalus as a test bed, one is able to account for the necessary mechanisms involved in the interaction between oedema formation and cerebral fluid production, transport and drainage. The current state of knowledge about integrative cerebral dynamics and transport phenomena indicates that poroelastic theory may provide a suitable framework to better understand various diseases. In this work, Multiple-Network Poroelastic Theory (MPET) is used to develop a novel spatio-temporal model of fluid regulation and tissue displacement within the various scales of the cerebral environment. The model is applied through two formats, a one-dimensional finite difference – Computational Fluid Dynamics (CFD) coupling framework, as well as a two-dimensional Finite Element Method (FEM) formulation. These are used to investigate the role of endoscopic fourth ventriculostomy in alleviating oedema formation due to fourth ventricle outlet obstruction (1D coupled model) in addition to observing the capability of the FEM template in capturing important characteristics allied to oedema formation, like for instance in the periventricular region (2D model).

Highlights

IntroductionHCP that possesses no radiographically identifiable flow obstruction, there is evidence of craniomegaly and ventriculomegaly taking place [11,12]
The fact that a complete tri-exit closure did not correspond to even higher levels of volume dilation and effective stress than individual outlet atresia highlights the need to further investigate the role of the central canal in such circumstances, in addition to the likelihood that convective cerebrospinal fluid (CSF)/ISF fluxes are heavily influenced by the reactive nature of astrocytes, which could lead to AQP4 depolarization from vascular end-feet and migrate to astrocyte parenchymal processes [46], and be associated with glymphatic pathway impairment [47]
This study has outlined the application of a multicompartmental poroelastic framework to investigate interstitial oedema formation and its alleviation, using a simple 1D model

Summary

Introduction

HCP that possesses no radiographically identifiable flow obstruction, there is evidence of craniomegaly and ventriculomegaly taking place [11,12]. Hydrocephalus (HCP) can be defined as the abnormal accumulation of CSF within the brain [1,7]. HCP itself is not a singular pathological entity, but instead, a consequence of a variety of congenital and acquired disorders present within the central nervous system (CNS) [9]. HCP is classified with regards to whether the point of CSF obstruction or discreet lesion lies within the ventricular system (obstructive) and obstructs the flow before it enters the subarachnoid space (SAS) [10], or not (communicating). Normal Pressure Hydrocephalus (NPH) is a form of

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