Biomechanics of Hydrocephalus: A new theoretical model

Abstract

The finite element method (FEM) , an advanced method of computer simulation, is used to examine biomechanieal studies of hydrocephalus. Biot's theory of consolidation, whieh describes the mechanical behavior of a porous medium containing viscous fluid, is applied to represent the coupled behavior of tissue and fluid in the hydrocephalic brain . A computer simulation of the hydrocephalic process is carried out by FEM to evaluate the mathematical model. A two-dimensional finite element model is constructed using a horizontal computed tomographie (CT) slice of the brain. Specifying the material properties of the brain parenchyma , the loading characteristics, and the boundary conditions, the change of interstitial pressure, intracerebral stress distribution , and ventricular configuration are computed and graphieally represented. The result s of the computer simulation are compared with the findings of CT and magnetie resonance imaging of hydrocephalic patients. The progress of periventrieular cerebrospinal fluid edema and ventrieular enlargement is weIl represented by the mathematical model. The model demonstrated that stress concentration in the brain tissue and increased parenchymal hydraulie conductivity play an important roIe in the generation of periventricular cerebrospinal fluid edema. (Neurosurgery 21: 898-904 , 1987)

New experimental model of acute aqueductal blockage in cats: Effects on cerebrospinal fluid pressure and the size of brain ventricles

“…The pressure gradient is often associated with the occurrence of hydrocephalus, particularly the acute one, and some authors view it as the fundamental mechanism of hydrocephalus development regardless of whether a low gradient (Conner et al, 1984;Hakim and Hakim, 1984;Penn, 2005;Levine, 2008) or a high gradient is in question (Nagashima et al, 1987;Kaczmarek et al, 1997;Smillic et al, 2005). There are, nevertheless, some other authors who believe that CSF pressure gradient is not possible within the cranium firmly enclosed by bones, and more so because they did not observe such a gradient either in experiments involving animals (Shapiro et al, 1987) or in patients with communicating or noncommunicating hydrocephalus (Stephensen et al, 2002).…”

The formation of cerebrospinal fluid: Nearly a hundred years of interpretations and misinterpretations

“…It is also not clear if the pressure gradient is often associated with the occurrence of hydrocephalus, particularly the acute one, and some authors view it as the fundamental mechanism of hydrocephalus development regardless of whether a low gradient (Conner et al, 1984;Hakim and Hakim, 1984;Levine, 2008;Penn et al, 2005) or a high gradient is in question (Kaczmarek et al, 1997;Nagashima et al, 1987;Smillic et al, 2005). There are, nevertheless, some other authors who believe that CSF pressure gradient is not possible within the cranium firmly enclosed by bones, mostly because they did not observe such a gradient neither in experiments involving animals (Shapiro et al, 1987) nor in patients with communicating or non-communicating hydrocephalus (Stephensen et al, 2002).…”

Development of hydrocephalus and classical hypothesis of cerebrospinal fluid hydrodynamics: Facts and illusions

“…It seems that without such a gradient it would be difficult to conceptualize how brain ventricular dilatation occurs. It is equally unclear if the pressure gradient can really be the fundamental mechanism of hydrocephalus development, regardless of whether it is low (Conner et al, 1984;Hakim and Hakim, 1984;Levine, 2008;Penn et al, 2005) or high (Kaczmarek et al, 1997;Nagashima et al, 1987;Smillic et al, 2005). There are, nevertheless, some other authors who believe that a CSF pressure gradient is not possible within the cranium firmly enclosed by bones, mostly because they did not observe such a gradient neither in experiments involving animals (Shapiro et al, 1987) nor in patients with communicating or non-communicating hydrocephalus (Stephensen et al, 2002).…”