Cerebrospinal Fluid Viscosity: A Novel Diagnostic Measure for Acute Meningitis

Yetkin, Funda; Kayabaş, Üner; Ersoy, Yasemin; Bayındır, Yaşar; Toplu, Sibel Altunisik; Tek, Ibrahim

doi:10.1097/smj.0b013e3181ebe260

Cited by 29 publications

(17 citation statements)

References 10 publications

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“…Figure 4 Measurements of the valve introduced in the emulated CSF with 10% blood at ~ 38 -40 °C shifts operation to a lower R h as expected based on the lower viscosity of the heated in vitro fluid (~ 0.72 mPa·s) relative to that of water at 23 °C (~ 0.936 mPa·s). 27 Figure 4 μm, and r i = 250 μm tested in three different working environments (water, 10% aqueous microparticle suspension, and aCSF). The latter valve displays less variation that is likely owing to its larger size.…”

Section: Basic Hydrodynamic Valve Characteristicsmentioning

confidence: 99%

In Vitro Hydrodynamic, Transient, and Overtime Performance of a Miniaturized Valve for Hydrocephalus

et al. 2015

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Reliable cerebrospinal fluid (CSF) draining methods are needed to treat hydrocephalus, a chronic debilitating brain disorder. Current shunt implant treatments are characterized by high failure rates that are to some extent attributed to their length and multiple components. The designed valve, made of hydrogel, steers away from such protracted schemes and intends to provide a direct substitute for faulty arachnoid granulations, the brain's natural CSF draining valves, and restore CSF draining operations within the cranium. The valve relies on innate hydrogel swelling phenomena to strengthen reverse flow sealing at idle and negative pressures thereby alleviating common valve failure mechanisms. In vitro measurements display operation in range of natural CSF draining (cracking pressure, PT ~ 1-110 mmH2O and outflow hydraulic resistance, Rh ~ 24-152 mmH2O/mL/min), with negligible reverse flow leakage (flow, QO > -10 µL/min). Hydrodynamic measurements and over-time tests under physically relevant conditions further demonstrate the valve's operationally-reproducible properties and strengthen its validity for use as a chronic implant.

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Section: Basic Hydrodynamic Valve Characteristicsmentioning

confidence: 99%

In Vitro Hydrodynamic, Transient, and Overtime Performance of a Miniaturized Valve for Hydrocephalus

et al. 2015

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“…This was chosen because dye injected through the cisterna magna enters the PVS nearly 10 times faster than it enters the parenchyma (<5 minutes vs. ~30 mins) 44 , presumably under a single source of difference in uid pressure. The viscosity (0.001 Pa*s) and density (1000 kg/m 3 ) of CSF were taken from experimentally determined values 45,46 .…”

Section: Modeling Choicesmentioning

confidence: 99%

Functional hyperemia drives fluid exchange in the paravascular space

Kedarasetti

Turner

Echagarruga

et al. 2020

Preprint

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The brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that directional fluid movement through the arteriolar paravascular space (PVS) promotes metabolite clearance. We performed simulations to examine if arteriolar pulsations and dilations can drive directional CSF flow in the PVS and found that arteriolar wall movements do not drive directional CSF flow. We propose an alternative method of metabolite clearance from the PVS, namely fluid exchange between the PVS and the subarachnoid space (SAS). In simulations with compliant brain tissue, arteriolar pulsations did not drive appreciable fluid exchange between the PVS and the SAS. However, when the arteriole dilated, as seen during functional hyperemia, there was a marked exchange of fluid. Simulations suggest that functional hyperemia may serve to increase metabolite clearance from the PVS. We measured blood vessels and brain tissue displacement simultaneously in awake, head-fixed mice using two-photon microscopy. These measurements showed that brain deforms in response to pressure changes in PVS, consistent with our simulations. Our results show that the deformability of the brain tissue needs to be accounted for when studying fluid flow and metabolite transport.Acknowledgements: This work was supported by NSF Grant CBET 1705854.

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“…The width of the PVS was between 2-10 µm 1,9,78 . The viscosity (0.001 Pa*s) and density (1000 kg/m 3 ) of CSF were taken from experimentally determined values 79,80 .…”

Section: Model Parametersmentioning

confidence: 99%

Functional hyperemia drives fluid exchange in the paravascular space

Kedarasetti

Turner

Echagarruga

et al. 2019

Preprint

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Maintaining the ionic and chemical composition of the extracellular spaces in the brain is extremely important for its health and function. However, the brain lacks a conventional lymphatic system to remove metabolic waste. It has been proposed that the fluid movement through the paravascular space (PVS) surrounding penetrating arteries can help remove metabolites from the brain. The dynamics of fluid movement in the PVS and its interaction with arterial dilation and brain mechanics are not well understood. Here, we performed simulations to understand how arterial pulsations and dilations interact with brain deformability to drive fluid flow in the PVS. In simulations with compliant brain tissue, arterial pulsations did not drive appreciable flows in the PVS. In contrast, when the artery dilated with dynamics like those seen during functional hyperemia, there was a marked movement of fluid through the PVS. Our simulations suggest that in addition to its other purposes, functional hyperemia may serve to increase fluid exchange between the PVS and the subarachnoid space, improving the clearance of metabolic waste. We measured displacement of the blood vessels and the brain tissue simultaneously in awake, headfixed mice using two-photon microscopy. Our measurements show that brain tissue can deform in response to fluid movement in the PVS, as predicted by simulations. The results from our simulations and experiments show that the deformability of the soft brain tissue needs to be accounted for when studying fluid flow and metabolite transport in the brain.

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Cerebrospinal Fluid Viscosity: A Novel Diagnostic Measure for Acute Meningitis

Abstract: The CSF viscosity is a simple and easy method and can be used as an adjunctive measure for the diagnosis of meningitis. With the support of further and larger clinical studies, CSF viscosity may have a role in the discrimination of bacterial versus aseptic meningitis.

Cited by 29 publications

References 10 publications

In Vitro Hydrodynamic, Transient, and Overtime Performance of a Miniaturized Valve for Hydrocephalus

In Vitro Hydrodynamic, Transient, and Overtime Performance of a Miniaturized Valve for Hydrocephalus

Functional hyperemia drives fluid exchange in the paravascular space

Functional hyperemia drives fluid exchange in the paravascular space

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