Cerebrospinal Fluid Homeostasis and Hydrodynamics: A Review of Facts and Theories

Abstract

<b><i>Background and Purpose:</i></b> According to the classical hypothesis, the cerebrospinal fluid (CSF) is actively secreted inside the brain’s ventricular system, predominantly by the choroid plexuses, before flowing unidirectionally in a cranio-caudal orientation toward the arachnoid granulations (AGs), where it is reabsorbed into the dural venous sinuses. This concept has been accepted as a doctrine for more than 100 years and was subjected only to minor modifications. Its inability to provide an adequate explanation to questions arising from the everyday clinical practice, in addition to the ever growing pool of experimental data contradicting it, has led to the identification of its limitations. Literature includes an increasing number of studies suggesting a more complex mechanism than that previously described. This review article summarizes the proposed mechanisms of CSF regulation, referring to the key clinical and experimental developments supporting or defying them. <b><i>Methods:</i></b> A non-systematical literature search of the major databases was performed for studies on the mechanisms of CSF homeostasis. Gray literature was additionally assessed employing a hand-search technique. No restrictions were imposed regarding the time, language, or type of publication. <b><i>Conclusion:</i></b> CSF secretion and absorption are expected to take place throughout the entire brain’s capillaries network under the regulation of hydrostatic and osmotic gradients. The unidirectional flow is defied, highlighting the possibility of its complete absence. The importance of AGs is brought into question, potentiating the significance of the lymphatic system as the primary site of reabsorption. However, the definition of hydrocephalus and its treatment strategies remain strongly associated with the classical hypothesis.

Molecular and Cellular Analysis of the Repair of Zebrafish Optic Tectum Meninges Following Laser Injury

“…We therefore suggest that these cells may be RBC/thrombocytes located in venous sinuses known as cisterns. It has been suggested that these structures drain cerebrospinal fluid (CSF) via arachnoid granulations following the one-way circulation of the CSF through the subarachnoid space after its production in the choroid plexus [29][30][31]. We identified six domains of EGFP-positive cells on the basis of cell distributi shape.…”

“…-Arachnoid cells (ARA), color-coded in yellow. This population of cells with strong, positive EGFP staining was located in the so-called arachnoid space [32,33] at the periphery of the OT, at the surface of the cisterns [29][30][31], adjacent to the telencephalon and cerebellum (Figure 1A,G). In mammals [18,19], the subarachnoid space also extends between the telencephalon and midbrain, and between the midbrain and cerebellum.…”

Application of Metabolomics in Childhood Leukemia Diagnostics

“…An aspect of the bioinformatics analysis of metabolomics data is the appropriate visualization of the obtained results. Only after the use of effective bioinformatics tools for data visualization, it is possible to maximally simplify the comprehensive comparative analysis of multidimensional databases (van der Greef et al 2013;Wang et al 2011). Building reference databases of chemical compounds is very important for the correct identification of cellular metabolites.…”

“…Progress in bioanalytical science made it possible to use advanced technologies, such as nuclear magnetic resonance (NMR) or mass spectrometry (MS), and this in turn forced the development of appropriate mathematical tools for processing the huge amounts of data obtained as a result of research. Thus, although studies of cellular metabolism or quantification of metabolic processes are not new in science, it was not until the end of the twentieth century that it became possible to perform a comprehensive analysis of virtually all metabolites found in cell fluids (Brindle 2015;Clarke and Foster 2012;van der Greef et al 2004).…”

Brain Stroke Lesion Segmentation Using Computed Tomography Images based on Modified U-Net Model with ResNet Blocks

“…For stroke diagnosis, the most widely employed imaging techniques are computed tomography (CT) and magnetic resonance imaging (MRI). CT scans are the most commonly used technique for the diagnostics of intraventricular hemorrhage [4]. All patients may benefit from CT scans since they are generally accessible, affordable and quick.…”