Biomechanics of Hydrocephalus: A New Theoretical Model

Nagashima, Tatsuya; Tamaki, Norihiko; Matsumoto, Satoshi; Horwitz, Barry; Seguchi, Yasuyuki

doi:10.1227/00006123-198712000-00019

Cited by 118 publications

(48 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…FE analysis of the hydrocephalic brain can simulate the main features of hydrocephalus, such as structural deformation, ventricular enlargement, PVL, and cerebral edema; thus, it is widely considered a valid approach to assess biomechanical changes in the hydrocephalic brain. 5,6,9,19,26,30,39,42,43,45 …”

Section: Methodsmentioning

confidence: 99%

“…The negative pore pressure (i.e., the fluid influx) in the periventricular region was visible when the degree of The void ratio of parenchyma is 0.2. 26 The permeability of white and gray matter is 1 × 10 −7 and 1 × 10 −9 , respectively. 17 The compressibility parameter D 1 (224 Pa) and shear parameter C 10 (77.9 Pa) of the parenchyma were calculated from Young's modulus and Poisson's ratio, in accordance with the neoHookean model for describing compressible biological tissue.…”

Section: Periventricular Lucency In the Fe Hydrocephalic Brain Modelmentioning

confidence: 99%

“…The method has been increasingly used to assess the biomechanical behavior of the hydrocephalic brain since the pioneering study of Nagashima et al in 1987. 26 The present study was based on the hypothesis that the changes in geometrical characteristics of the brain induced by ventricular enlargement could affect aspects of PVL. This possible relationship was investigated with a geometrically detailed FE hydrocephalic brain model, thereby providing insights into the clinical significance of PVL.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?

Kim¹,

Jeong

Park³

et al. 2016

JNS

View full text Add to dashboard Cite

P eriventricular lucency (PVL) refers to the decreased attenuation level, or "blurring," around the periventricular area on CT, or T2 hyperintensity on MRI. This radiological phenomenon is a common finding not only in various neurological or cardiovascular disorders, but also in the general elderly population. 21,22,29,47 Although widely researched and documented, the pathogenesis and clinical significance of PVL are still inconclusive, especially for PVL associated with hydrocephalus. Hydrocephalus is defined as the excessive accumulation of CSF in the brain due to various causes. The disease is considered to be caused by an imbalance between the formation and reabsorption of CSF, due to the disturbance in CSF dynamics. 28 Considering the site of the obstruction in the flow of CSF, two types of hydrocephalus have been defined: communicating and noncommunicating. PVL in hydrocephalus was first documented by Naidich et al. 27PVL and enlarged ventricles are typical radiological signs of acute or noncommunicating hydrocephalus.30 However, these two signs also exist in chronic or communicating hydrocephalus, although the prevalence is relatively lower. 25,34 In either case, the pathogenesis of PVL remains abbreviatioNs FE = finite element; ICP = intracranial pressure; ISF = interstitial fluid; PVL = periventricular lucency; TPG = transmantle pressure gradient. obJective Periventricular lucency (PVL) is often observed in the hydrocephalic brain on CT or MRI. Earlier studies have proposed the extravasation of ventricular CSF into the periventricular white matter or transependymal CSF absorption as possible causes of PVL in hydrocephalus. However, there is insufficient evidence for either theory to be conclusive. methods A finite element (FE) model of the hydrocephalic brain with detailed anatomical geometry was constructed to investigate the possible mechanism of PVL in hydrocephalus. The initiation of hydrocephalus was modeled by applying a transmantle pressure gradient (TPG). The model was exposed to varying TPGs to investigate the effects of different geometrical characteristics on the distribution of PVL. The edema map was derived based on the interstitial pore pressure. results The model simulated the main radiological features of hydrocephalus, i.e., ventriculomegaly and PVL. The degree of PVL, assessed by the pore pressure, was prominent in mild to moderate ventriculomegaly. As the degree of ventriculomegaly exceeded certain values, the pore pressure across the cerebrum became positive, thus inducing the disappearance of PVL. coNclusioNs The results are in accordance with common clinical findings of PVL. The degree of ventriculomegaly significantly influences the development of PVL, but two factors were not linearly correlated. The results are indicative of the transependymal CSF absorption as a possible cause of PVL, but the extravasation theory cannot be formally rejected.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Periventricular Lucency In the Fe Hydrocephalic Brain Modelmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?

Kim¹,

Jeong

Park³

et al. 2016

JNS

View full text Add to dashboard Cite

show abstract

“…We used the ‘negatively symmetric nonlinear model’ [13]to estimate the volume shifts. While conventional mathematical models of the pressure-volume relationship in the human central nervous system [29, 30, 31, 32]were developed to understand the CSF dynamics in supine position, they cannot be extrapolated to allow calculations involving negative pressures in the upright position. We therefore used the ‘negatively symmetric nonlinear model’ [13]that is decidedly superior to using the conventional curves, which become mathematically void for negative pressure estimations (since there is no estimable log of a negative pressure).…”

Section: Discussionmentioning

confidence: 99%

Postural Changes in Intracranial Pressure in Chronically Shunted Patients

et al. 2000

View full text Add to dashboard Cite

A subset of hydrocephalic patients with indwelling shunts become symptomatic when they are upright and active. Intracranial pressure (ICP) measurements in these patients have shown a significant drop in pressure when the patient is upright with return to normal levels when the patient is supine. In 20 chronically shunted hydrocephalic patients who previously had no siphon protection devices, ICP changes in supine and upright position were studied at the time when the patient had external ventriculostomy for treatment of shunt infection. Our hypothesis was that these patients might display rapid changes in ICP from fluid shifts occurring in non-CSF compartments. To minimize the effects of hysteresis, drift and zero-point error, measurements were made using a fluid manometer rather than a strain gauge pressure transducer. The pressure-volume index was estimated using the standard technique of bolus injection. Intracranial CSF volume was estimated on CT scans. The fluid shift was calculated using a mathematical model of the CSF compartment that incorporates negative pressure and volume components that permits simulation of siphoning. Sixteen patients had small, slit ventricles; 3 patients had moderate-sized ventricles and in 1 patient the ventricular size was normal. The average intracranial CSF volume estimated on CT scan was 12 cm³. There was a mean drop in ICP in the upright position of 159 mm H₂O. The mean PVI of 42 ml suggested a volume displacement out of proportion to the available intracranial CSF volume. Based on these findings, we conclude that even in the absence of drainage through the shunt, chronically shunted patients still display a fall in ICP when assuming the upright position. This raises the possibility of fluid shifts other than of CSF through nonshunt pathways. Possible mechanisms involving altered CSF-venous system interaction are discussed.

show abstract

“…Several studies have been carried out experimentally to elucidate the unclear mechanism of NPH [9][10][11]. Due to the difficulty in performing experimental studies, interest in analytical and numerical approaches has increased [12][13][14]. Among these approaches, Levine highlighted the role of interstitial fluid (ISF) absorption as a source of compliance in a spherical model of brain [15].…”

Section: Introductionmentioning

confidence: 99%

Ventricle Equilibrium Position in Healthy and Normal Pressure Hydrocephalus Brains Using an Analytical Model

Shahim¹,

Drezet

Martin

et al. 2012

Journal of Biomechanical Engineering

View full text Add to dashboard Cite

The driving force that causes enlargement of the ventricles remains unclear in case of normal pressure hydrocephalus (NPH). Both healthy and NPH brain conditions are characterized by a low transparenchymal pressure drop, typically 1 mm Hg. The present paper proposes an analytical model for normal and NPH brains using Darcy's and Biot's equations and simplifying the brain geometry to a hollow sphere with an internal and external radius. Self-consistent solutions for the large deformation problem that is associated with large ventricle dilation are presented and the notion of equilibrium or stable ventricle position is highlighted for both healthy and NPH conditions. The influence of different biomechanical parameters on the stable ventricle geometry is assessed and it is shown that both CSF seepage through the ependyma and parenchymal permeability play a key role. Although very simple, the present model is able to predict the onset and development of NPH conditions as a deviation from healthy conditions.

show abstract

Biomechanics of Hydrocephalus: A New Theoretical Model

Cited by 118 publications

References 0 publications

Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?

Finite element analysis of periventricular lucency in hydrocephalus: extravasation or transependymal CSF absorption?

Postural Changes in Intracranial Pressure in Chronically Shunted Patients

Ventricle Equilibrium Position in Healthy and Normal Pressure Hydrocephalus Brains Using an Analytical Model

Contact Info

Product

Resources

About