Abstract

GARCIA, J. J.  and  SMITH, J. H.. A biphasic hyperelastic model for hydrocephalus. Lat. Am. appl. res. [online]. 2010, vol.40, n.4, pp.295-302. ISSN 0327-0793.

A biphasic hyperelastic model with spherical symmetry is presented to study hydrocephalus. The model can take into account the biphasic nature of brain tissue, non-linear stress-strain curves through an Ogden-type compressible strain energy function, a nonlinear variation of hydraulic conductivity with deformation, a constant production of cerebrospinal fluid (CSF) as well as a fluid absorption rate proportional to pressure. The biphasic equations were implemented in an updated Lagrangian finite element code where a novel procedure was devised to consider the constant generation of CSF in the ventricles. Results of a non-communicating model showed strains in the range of 35-45% in the peri-ventricular area and pore pressure and radial displacement distributions that were not significantly affected by material nonlinearities. High circumferential stresses documented in acute hydrocephalus suggest that the tissue may suffer damage at the ventricular surface while a communicating model was not capable of reproducing normal pressure hydrocephalus. Overall results suggest that normal pressure hydrocephalus cannot be explained with models that consider an elastic law for the solid phase of the material.

Keywords : Acute Hydrocephalus; Normal Pressure Hydrocephalus; Porohyperelastic Model; Hyperelastic Biphasic Model.

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