Cerebrospinal Fluid Mechanics and Its Coupling to Cerebrovascular Dynamics

Abstract

Cerebrospinal fluid (CSF) is not stagnant but displays fascinating oscillatory flow patterns inside the ventricular system and reversing fluid exchange between the cranial vault and spinal compartment. This review provides an overview of the current knowledge of pulsatile CSF motion. Observations contradicting classical views about its bulk production and clearance are highlighted. A clinical account of diseases of abnormal CSF flow dynamics, including hydrocephalus, syringomyelia, Chiari malformation type 1, and pseudotumor cerebri, is also given. We survey medical imaging modalities used to observe intracranial dynamics in vivo. Additionally, we assess the state of the art in predictive models of CSF dynamics. The discussion addresses open questions regarding CSF dynamics as they relate to the understanding and management of diseases. 219 P R E V I E WFL48CH09-Linninger ARI

New Concepts of Cerebrospinal Fluid Physiology and Development of Hydrocephalus

“…Until now, this hypothesis was named Bulat-Klarica-Orešković hypothesis by several research groups [34,[38][39][40] , and it is supported by independent experimental laboratories [34,39,44,45] as well as by computer-based models [46,47] and critically analyzed clinical data [39,40] .…”

Hydrocephalus: the role of cerebral aquaporin-4 channels and computational modeling considerations of cerebrospinal fluid

“…6,17,40,49,50,58,77,78 Previous models of hydrocephalus divided the cranial space into individual compartments, such as ventricles, parenchyma, cerebral blood, and cranial subarachnoidal space. Externally imposed changes to fluid exchange between these compartments, such as obstruction of the villi, induce accumulation of the fluid and subsequently lead to CSF accumulation in the ventricular system.…”

“…A recent review by Linninger et al summarized models of CSF dynamics and diseases. 77 Most existing computational models use an incompressible fluid assumption that does not set a specific value for absolute hydrostatic pressure (ICP). Thus incompressibility merely implies a "pressure drop" needed to entertain fluid motion by overcoming viscous frictional losses, but it does not correlate to absolute ICP.…”

“…In obstructive hydrocephalus, current treatment involves restoring normal CSF flow, either by removing the obstructive lesion or by creating a bypass of the obstruction. 77 In primary malabsorptive hydrocephalus, such as in malabsorption at arachnoid villi, shunting of CSF from the brain has been shown to be lifesaving in a disease process that was fatal as little as 65 years ago. 77 The integration of ICP, ventricular volume, and the relationship of osmolarity to molecular AQP4 pathology is difficult to intuitively align with clinical enlargement of the ventricles, and observed changes in volume and pressure parameters.…”

“…77 In primary malabsorptive hydrocephalus, such as in malabsorption at arachnoid villi, shunting of CSF from the brain has been shown to be lifesaving in a disease process that was fatal as little as 65 years ago. 77 The integration of ICP, ventricular volume, and the relationship of osmolarity to molecular AQP4 pathology is difficult to intuitively align with clinical enlargement of the ventricles, and observed changes in volume and pressure parameters. Use of computational models may potentially help clinicians to better design bypass strategies in noncommunicating hydrocephalus, complement shunt device placement in communicating hydrocephalus, and aid surgical planning for disorders of CSF flow.…”