Parameter estimations for the cerebrospinal fluid infusion test.

We consider parameter estimation for a single compartment model of a cerebrospinal fluid (CSF) infusion test using an inverse power law cerebral compliance depending on intracranial pressure (ICP). A least squares optimization is used to solve the inverse problem of estimating model parameter values from ICP observed during an infusion test. The optimization is applied to synthetic test data and to clinical ICP data from a number of infusion tests.

Analytic solution during an infusion test of the linear unsteady poroelastic equations in a spherically symmetric model of the brain.

This work determines the spatial and temporal distribution of cerebrospinal fluid (CSF) pressure and brain displacement during an infusion test in a spherically symmetric model of the brain. The response of CSF pressure and parenchymal displacement to blood pressure pulsations is determined in the solution. We use a spherically symmetric, three-component poroelastic model of the brain, differentiating between the solid elastic matrix, the CSF and the arterial blood compartments.

A model for an inverse power constitutive law for cerebral compliance.

This work provides a model that links the commonly used inverse power relationship between cerebral compliance and intracranial pressure to some mechanical properties of distal cerebral veins. The underlying model of the compliance is based on a mechanism whereby the distal cerebral blood vessels are assumed to be the main compliant part of the brain and cerebrospinal fluid volume changes are accommodated by blood displacement into or out of these vessels. This simplified model is not intended to produce a highly accurate prediction of the intracranial pressure-volume curve, which is best achieved by a numerical solution of more complicated models, but rather to justify the phenomenological inverse power law and to provide a basic interpretation of cerebral elasticity, reference pressure and exponent of the constitutive law in terms of underlying mechanical parameters.

An axisymmetric and fully 3D poroelastic model for the evolution of hydrocephalus.

We formulate in general terms the equations for axisymmetric and fully 3D models of a hydrocephalic brain. The model is developed using small strain poroelasticity that includes non-linear permeability. The axisymmetric model is solved for four ventricle shapes, an ellipsoid, a 'peanut' shape, a 'cross' shape and a 'bone' shape.

Effect of non-linear permeability in a spherically symmetric model of hydrocephalus.

We examine a spherically symmetric model of the brain and apply non-linear permeability in a small strain poroelastic framework. Numerical solutions to the model show that non-linear effects tend to improve predictions of ventricle wall displacement and pressure increase in acute hydrocephalus in comparison with a constant permeability model. Our model is used to study different mechanisms for hydrocephalus: complete blockage of the aqueduct and normal pressure hydrocephalus (NPH), as well as offering observations on mechanical effects in idiopathic intracranial hypertension.