Ventricular dilation as an instability of intracranial dynamics.
We address the question of the ventricles' dilation as a possible instability of the intracranial dynamics. The ventricular system is shown to be governed by a dynamical equation derived from first principles. This general nonlinear scheme is linearized around a well-defined steady state which is mapped onto a pressure-volume model with an algebraic effective compliance depending on the ventricles' geometry, the ependyma's elasticity, and the cerebrospinal fluid (CSF) surface tension. Instabilities of different natures are then evidenced. A first type of structural instability results from the compelling effects of the CSF surface tension and the elastic properties of the ependyma. A second type of dynamical instability occurs for low enough values of the aqueduct's conductance. This last case is then shown to be accompanied by a spontaneous ventricle's dilation. A strong correlation with some active hydrocephalus is evidenced and discussed. The transfer function of the ventricles, compared to a low-pass filter, are calculated in both the stable and unstable regimes and appear to be very different.
Bouzerar
R
R
Condensed Matter Physics Laboratory, UFR Sciences, Université de Picardie, 33 Rue Saint-Leu, 80039 Amiens, France. robert.bouzerar@sc.u-picardie.fr
Ambarki
K
K
Balédent
O
O
Kongolo
G
G
Picot
J C
JC
Meyer
M E
ME
D000818:Animals; D001683:Biological Clocks; D002552:Cerebral Ventricles / Q000503:physiopathology*; D002555:Cerebrospinal Fluid; D003198:Computer Simulation; D004108:Dilatation, Pathologic / Q000503:physiopathology*; D004548:Elasticity; D006801:Humans; D006849:Hydrocephalus / Q000503:physiopathology*; D007427:Intracranial Pressure; D008954:Models, Biological; D011312:Pressure