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Paravascular spaces: entry to or exit from the brain?
Erik N T P Bakker1, Daphne M P Naessens1, Ed VanBavel1
1Amsterdam UMC, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam Cardiovascular Sciences, Amsterdam, The Netherlands.
Experimental Physiology
|December 25, 2018
Summary
This review examines brain glymphatic clearance, highlighting that while cerebrospinal fluid (CSF) flows along the brain surface, its bulk flow into and out of the brain requires more evidence. Alternative mixing-based clearance mechanisms are also discussed.
Area of Science:
- Neuroscience
- Cerebrospinal Fluid Dynamics
- Brain Waste Clearance
Background:
- The brain's interstitial fluid is crucial for neuronal function.
- Regulation of interstitial fluid volume and composition is vital.
- The glymphatic pathway is a recently described system for fluid exchange.
Purpose of the Study:
- To review the glymphatic clearance concept in the brain.
- To discuss concerns and alternative viewpoints on interstitial fluid-cerebrospinal fluid exchange.
- To evaluate current evidence regarding glymphatic pathway function.
Main Methods:
- Review of existing scientific literature and symposium findings.
- Evaluation of experimental evidence for cerebrospinal fluid flow patterns.
- Analysis of proposed mechanisms for brain waste removal.
Main Results:
- Cerebrospinal fluid flow along the brain's surface paravascular spaces is supported by evidence.
- Bulk flow of cerebrospinal fluid into and out of the brain via arteries and veins needs further confirmation.
- Mixing-based clearance mechanisms may explain experimental observations.
Conclusions:
- The glymphatic pathway's role in brain fluid regulation requires further investigation.
- Alternative models for interstitial fluid-cerebrospinal fluid exchange warrant consideration.
- Continued research is necessary to fully understand brain clearance mechanisms.
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