Thanks to Sandro for this link. Cerebrospinal fluid (CSF) flow is essential for brain health and disruption of normal flow is related to neurodegenerative diseases, like MS.
"Recent insights into CSF biology suggesting that CSF and interstitial fluid exchange along a brain-wide network of perivascular spaces termed the 'glymphatic' system suggest that CSF circulation may interact intimately with glial and vascular function to regulate basic aspects of brain function. Dysfunction within this glial vascular network, which is a feature of the aging and injured brain, is a potentially critical link between brain injury, neuroinflammation and the development of chronic neurodegeneration." http://www.ncbi.nlm.nih.gov/pubmed/26499397

Biochim Biophys Acta. 2015 Oct 21. pii: S0925-4439(15)00314-2. doi: 10.1016/j.bbadis.2015.10.014. [Epub ahead of print] REVIEW