Cerebrospinal Fluid Absorption

Sahar, Abraham; Hochwald, G. M.; Sadik, Abdul R.; Ransohoff, Joseph

doi:10.1001/archneur.1969.00480180094009

Cited by 57 publications

(5 citation statements)

References 13 publications

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“…The rapid ventricular enlargement in the initial stage of acute hydrocephalus development may be caused by the increase in CSF pressure due to the obstruction of CSF pathway, as suggested previously [ 47 ]. After this acute period, it has been previously shown, in a cat model, that transventricular absorption of CSF occurs [ 48 , 49 ]. This may mitigate further increases in CSF pressure, and slow down ventricular enlargement.…”

Section: Discussionmentioning

confidence: 99%

Changes in Rat Brain Tissue Microstructure and Stiffness during the Development of Experimental Obstructive Hydrocephalus

et al. 2016

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Understanding neural injury in hydrocephalus and how the brain changes during the course of the disease in-vivo remain unclear. This study describes brain deformation, microstructural and mechanical properties changes during obstructive hydrocephalus development in a rat model using multimodal magnetic resonance (MR) imaging. Hydrocephalus was induced in eight Sprague-Dawley rats (4 weeks old) by injecting a kaolin suspension into the cisterna magna. Six sham-injected rats were used as controls. MR imaging (9.4T, Bruker) was performed 1 day before, and at 3, 7 and 16 days post injection. T2-weighted MR images were collected to quantify brain deformation. MR elastography was used to measure brain stiffness, and diffusion tensor imaging (DTI) was conducted to observe brain tissue microstructure. Results showed that the enlargement of the ventricular system was associated with a decrease in the cortical gray matter thickness and caudate-putamen cross-sectional area (P < 0.001, for both), an alteration of the corpus callosum and periventricular white matter microstructure (CC+PVWM) and rearrangement of the cortical gray matter microstructure (P < 0.001, for both), while compression without gross microstructural alteration was evident in the caudate-putamen and ventral internal capsule (P < 0.001, for both). During hydrocephalus development, increased space between the white matter tracts was observed in the CC+PVWM (P < 0.001), while a decrease in space was observed for the ventral internal capsule (P < 0.001). For the cortical gray matter, an increase in extracellular tissue water was significantly associated with a decrease in tissue stiffness (P = 0.001). To conclude, this study characterizes the temporal changes in tissue microstructure, water content and stiffness in different brain regions and their association with ventricular enlargement. In summary, whilst diffusion changes were larger and statistically significant for majority of the brain regions studied, the changes in mechanical properties were modest. Moreover, the effect of ventricular enlargement is not limited to the CC+PVWM and ventral internal capsule, the extent of microstructural changes vary between brain regions, and there is regional and temporal variation in brain tissue stiffness during hydrocephalus development.

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Section: Discussionmentioning

confidence: 99%

Changes in Rat Brain Tissue Microstructure and Stiffness during the Development of Experimental Obstructive Hydrocephalus

et al. 2016

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“…Thus chronically the CSF must escape. It was assumed by those who developed this model that the route was by ventricular absorption [220, 497, 498] and it was used in attempts to investigate this process. However, it has now been shown convincingly, at least in cats, that in chronic kaolin induced hydrocephalus there is almost no ventricular absorption [223].…”

mentioning

confidence: 99%

Fluid and ion transfer across the blood–brain and blood–cerebrospinal fluid barriers; a comparative account of mechanisms and roles

Hladky

Barrand

2016

Fluids Barriers CNS

221

253

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The two major interfaces separating brain and blood have different primary roles. The choroid plexuses secrete cerebrospinal fluid into the ventricles, accounting for most net fluid entry to the brain. Aquaporin, AQP1, allows water transfer across the apical surface of the choroid epithelium; another protein, perhaps GLUT1, is important on the basolateral surface. Fluid secretion is driven by apical Na+-pumps. K+ secretion occurs via net paracellular influx through relatively leaky tight junctions partially offset by transcellular efflux. The blood–brain barrier lining brain microvasculature, allows passage of O2, CO2, and glucose as required for brain cell metabolism. Because of high resistance tight junctions between microvascular endothelial cells transport of most polar solutes is greatly restricted. Because solute permeability is low, hydrostatic pressure differences cannot account for net fluid movement; however, water permeability is sufficient for fluid secretion with water following net solute transport. The endothelial cells have ion transporters that, if appropriately arranged, could support fluid secretion. Evidence favours a rate smaller than, but not much smaller than, that of the choroid plexuses. At the blood–brain barrier Na+ tracer influx into the brain substantially exceeds any possible net flux. The tracer flux may occur primarily by a paracellular route. The blood–brain barrier is the most important interface for maintaining interstitial fluid (ISF) K+ concentration within tight limits. This is most likely because Na+-pumps vary the rate at which K+ is transported out of ISF in response to small changes in K+ concentration. There is also evidence for functional regulation of K+ transporters with chronic changes in plasma concentration. The blood–brain barrier is also important in regulating HCO3 − and pH in ISF: the principles of this regulation are reviewed. Whether the rate of blood–brain barrier HCO3 − transport is slow or fast is discussed critically: a slow transport rate comparable to those of other ions is favoured. In metabolic acidosis and alkalosis variations in HCO3 − concentration and pH are much smaller in ISF than in plasma whereas in respiratory acidosis variations in pHISF and pHplasma are similar. The key similarities and differences of the two interfaces are summarized.

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“…Transependymal CSF flow can be explained partially by the studies done on experimental hydrocephalus models during the 60s. Early evidence is provided by animal studies: using radioactive-labeled substances, it turned out that the infused compound crosses the periventricular ependymal layer towards the extracellular space [ 22 , 23 ]. Later, in a dog model of chronic communicating hydrocephalus, James and co-workers used a radioactive isotope of [ 131 I] serum albumin, which was slowly infused intraventricularly, and animals were subjected to autoradiography.…”

Section: Transependymal Csf Flowmentioning

confidence: 99%

“…For instance, histological and ultrastructural investigation on the brains with periventricular oedema have shown that distinct dynamic processes are involved in CSF crossing through brain parenchyma [ 21 ]. In a different study, inulin or sucrose, substances that are bound to the extracellular space of the brain parenchyma, diffuses from the ventricle into the neuropil [ 22 , 30 ].…”

Section: Transependymal Csf Flowmentioning

confidence: 99%

Transependymal Cerebrospinal Fluid Flow: Opportunity for Drug Delivery?

et al. 2017

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Drug delivery to the central nervous system (CNS) is complicated by the blood-brain barrier. As a result, many agents that are found to be potentially effective at their site of action cannot be sufficiently or effectively delivered to the CNS and therefore have been discarded and not developed further for clinical use, leaving many CNS diseases untreated. One way to overcome this obstacle is intracerebroventricular (ICV) delivery of the therapeutics directly to cerebrospinal fluid (CSF). Recent experimental and clinical findings reveal that CSF flows from the ventricles throughout the parenchyma towards the subarachnoid space also named minor CSF pathway, while earlier, it was suggested that only in pathological conditions such as hydrocephalus this form of CSF flow occurs. This transependymal flow of CSF provides a route to distribute ICV-infused drugs throughout the brain. More insight on transependymal CSF flow will direct more rational to ICV drug delivery and broaden its clinical indications in managing CNS diseases.

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Cerebrospinal Fluid Absorption

Cited by 57 publications

References 13 publications

Changes in Rat Brain Tissue Microstructure and Stiffness during the Development of Experimental Obstructive Hydrocephalus

Changes in Rat Brain Tissue Microstructure and Stiffness during the Development of Experimental Obstructive Hydrocephalus

Fluid and ion transfer across the blood–brain and blood–cerebrospinal fluid barriers; a comparative account of mechanisms and roles

Transependymal Cerebrospinal Fluid Flow: Opportunity for Drug Delivery?

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