The function and structure of the cerebrospinal fluid outflow system

Abstract

This review traces the development of our understanding of the anatomy and physiological properties of the two systems responsible for the drainage of cerebrospinal fluid (CSF) into the systemic circulation. The roles of the cranial and spinal arachnoid villi (AV) and the lymphatic outflow systems are evaluated as to the dominance of one over the other in various species and degree of animal maturation. The functional capabilities of the total CSF drainage system are presented, with evidence that the duality of the system is supported by the changes in fluid outflow dynamics in human and sub-human primates in hydrocephalus. The review also reconciles the relative importance and alterations of each of the outflow systems in a variety of clinical pathological conditions.

CSF dynamic analysis of a predictive pulsatility-based infusion test for normal pressure hydrocephalus

“…Alternative or additional pathways for CSF absorption via cranial nerve roots to the lymphatic system, as well as both secretion from and absorption to the capillaries and the interstitial fluid of the brain have been described. [29,30] The ventricles and part of the subarachnoid space is contained within the rigid confines of the skull, and thus interacts intimately with the arterial and venous systems through the fixed total volume these systems can inhabit. The Monro-Kellie doctrine states that any increase in the volume of brain matter, blood or CSF must be compensated for by an equal decrease in the other volumes.…”

“…Conventional knowledge posits that CSF is formed continually in the ventricles and circulates from there to the subarachnoid space surrounding the brain and spine before being absorbed into venous blood through structures called arachnoid granulations mainly located in the intracranial subarachnoid space [30,34]. The relationships describing the interactions of the volume and flow of CSF and the intracranial pressure (ICP) are referred to as the CSF dynamics.…”

The Distributional Nexus of Choroid Plexus to Cerebrospinal Fluid, Ependyma and Brain

“…Flow of CSF is from lateral ventricles to the third and then through the narrow mesencephalic aqueduct into the fourth ventricle. CSF advances toward drainage sites (Grzybowski et al 2006) by bulk flow (arrows 4 and 9, Figure 1) driven by a hydrostatic pressure gradient between CSF and venous blood (Johnston, Boulton, and Flessner 2000;Pollay 2010). CSF bulk flow distributes endogenous materials widely throughout the CNS.…”

Cranial Arachnoid Protrusions and Contiguous Diploic Veins in CSF Drainage

“…[1][2][3][4] Arachnoid granulations located adjacent to or in the cranial dural sinuses have been explored by using a variety of methods, including neuroimaging, [5][6][7][8][9][10][11][12][13][14][15] postmortem dissection, 5,16,17 investigations by using casting material, 18 and ex vivo studies. 1 However, no report has actually shown the process of CSF absorption in vivo.…”