Three-dimensional cerebrospinal fluid flow within the human ventricular system

Abstract

Cerebrospinal fluid (CSF) is a Newtonian fluid and can, therefore, be modelled using computational fluid dynamics (CFD). Previous modelling of the CSF has been limited to simplified geometric models. This work describes a geometrically accurate three dimensional (3D) computational model of the human ventricular system (HVS) constructed from magnetic resonance images (MRI) of the human brain. It is an accurate and full representation of the HVS and includes appropriately positioned CSF production and drainage locations. It was used to investigate the pulsatile motion of CSF within the human brain. During this investigation CSF flow rate was set at a constant 500 ml/day, to mimic real life secretion of CSF into the system, and a pulsing velocity profile was added to the inlets to incorporate the effect of cardiac pulsations on the choroid plexus and their subsequent influence on CSF motion in the HVS. Boundary conditions for the CSF exits from the ventricles (foramina of Magendie and Lushka) were found using a "nesting" approach, in which a simplified model of the entire central nervous system (CNS) was used to examine the effects of the CSF surrounding the ventricular system (VS). This model provided time varying pressure data for the exits from the VS nested within it. The fastest flow was found in the cerebral aqueduct, where a maximum velocity of 11.38 mm/s was observed over five cycles. The maximum Reynolds number recorded during the simulation was 15 with an average Reynolds number of the order of 0.39, indicating that CSF motion is creeping flow in most of the computational domain and consequently will follow the geometry of the model. CSF pressure also varies with geometry with a maximum pressure drop of 1.14 Pa occurring through the cerebral aqueduct. CSF flow velocity is substantially slower in the areas that are furthest away from the inlets; in some areas flow is nearly stagnant.

Characterization of CSF Hydrodynamics in the Presence and Absence of Tonsillar Ectopia by Means of Computational Flow Analysis

“…However, previous studies have suggested that these effects are small in CSF. 16 To determine whether these effects are important, future work will compare these results with a CFA method in which inertial effects are included; additional validation could be achieved with PCMR imaging at multiple levels or with a 3D PCMR technique.…”

“…14 CFA studies of the ventricular system have been performed, 15,16 but these are not relevant to the Chiari I malformation. Some physical models have been created; an in vitro study of syringomyelia hydrodynamics was performed with a phantom model of the spinal canal created from MR imaging.…”

MR Imaging of Papilledema and Visual Pathways: Effects of Increased Intracranial Pressure and Pathophysiologic Mechanisms

“…The high ICP compresses the ON at its junction with the globe and distends its prelaminar axons as their axoplasm piles up at the scleral lamina. 22 Howden et al 26 found that CSF velocity is substantially slower in areas farther away from its inlets and that at certain sites, the flow nearly stagnates. Therefore, any reduction in CSF flow rate should first affect the SAS of the ON, which is farther away from the ventricles and anatomically does not allow continuous flow.…”

“…Therefore, any reduction in CSF flow rate should first affect the SAS of the ON, which is farther away from the ventricles and anatomically does not allow continuous flow. 26 The ischemic theory postulates that elevated ICP causes reduced perfusion of the ON axons. The retrolaminar region of the ON is a watershed area and is prone to ischemic insult.…”

Flow induced by ependymal cilia dominates near-wall cerebrospinal fluid dynamics in the lateral ventricles

“…These are known to produce pulsatile CSF flow with velocities several orders of magnitude larger than those generated by the cilia [15][16][17][18][19][20]. Vice versa, none of the investigations of large-scale CSF dynamics has taken into account the effect of cilia motion.…”