The response of brain to transient elevations in intraventricular pressure

doi:10.1016/0022-510X(80)90107-0

Journal of the Neurological Sciences

Volume 48, Issue 3, December 1980, Pages 343-352

https://doi.org/10.1016/0022-510X(80)90107-0 Get rights and content

Abstract

A mathematical theory has been developed to evaluate the change in size of the cerebral ventricles in response to a square-wave pressure pulse within the ventricles. Specifically, the theory utilizes a lumped compartment viscoelastic spherical shell model of the brain and takes into account available creep compliance data. The pressure change in the cortical subarachnoid space plays a critical role in determining the net displacement of the brain. The rise in cortical subarachnoid pressure is governed by a rate constant γ which is nearly proportional to the absorption coefficient when absorption is rate-limiting, inversely proportional to the compliance of the spinal subarachnoid space, and also depends upon the resistance to flow through CSF pathways. A rapid rise in pressure within the cortical subarachnoid space results in an inward displacement of the ventricles immediately after the ventricular pressure pulse has ceased. Thereafter, the ventricles return toward their initial size as the pressure in the cortical subarachnoid space decays. A slow rise, on the other hand, favors permanent ventricular enlargement. Decreased absorption of CSF, long duration pulses, and bulk flow of CSF into brain, which are observed in hydrocephalus, all favor the development of ventricular enlargement.

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Information is also available from a century of animal model research and outcome data from more than half a century of successful treatment of hydrocephalus with shunts. Based on the newer information, there have been a number of attempts to create mathematic models that can improve understanding of mechanisms in hydrocephalus and better predict outcome (Avezaat et al., 1979; Marmarou et al., 1978; Spertell, 1980; van Eijndhoven and Avezaat, 1986; Rekate et al., 1988a). One of these models, based on points of potential restriction of the flow of CSF, has proved useful in understanding previously enigmatic conditions related to hydrocephalus, including idiopathic intracranial hypertension, normal-pressure hydrocephalus (NPH), and the syndrome of inappropriately low-pressure acute hydrocephalus (SILPAH), also called negative-pressure hydrocephalus (Rekate et al., 1988a; Filippidis et al., 2011; Rekate, 2011; Hamilton and Price, 2012).
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Our initial goal was to develop a mathematic model of ventricular volume regulation with a computer simulation of this control system. We began by evaluating previous attempts to develop mathematic models of intracranial biophysics to see how applicable they were to our needs.14,15 Our first requirement of the model was that it must be able to account for the 2 most enigmatic conditions of CSF dynamics, normal pressure hydrocephalus (NPH), and benign intracranial hypertension.16
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The response of brain to transient elevations in intraventricular pressure

Abstract

J. Biomech.

Exp. Neurol.

Circulation of the cerebrospinal fluid

J. Neurosurg.

Transport Phenomena

Formation and absorption of cerebrospinal fluid in man

Brain

Mechanics of Continua

Influence of systemic and cerebral vascular factors on the cerebrospinal fluid pulse waves

J. Neurosurg.