Is bulk flow plausible in perivascular, paravascular and paravenous channels?

• DOI: 10.1186/s12987-018-0103-8
• Publication Date: 2018-05-30T09:12:18Z
• Authors: Mohammad M. Faghih; M. Keith Sharp
• Keywords: Glymphatic System; Interstitial fluid; Pia mater; Interstitial space; Perivascular space; Parenchyma; Confined space; Subarachnoid space

Transport of solutes has been observed in the spaces surrounding cerebral arteries and veins. Indeed, transport found opposite directions two different around arteries. These findings have motivated hypotheses bulk flow within these spaces. The glymphatic circulation hypothesis involves cerebrospinal fluid from cortical subarachnoid space to parenchyma along paraarterial (extramural, Virchow-Robin) arteries, return (CSF) via paravenous channels. second interstitial lymphatic vessels basement membranes between arterial smooth muscle cells.This article evaluates plausibility steady, pressure-driven channels with one-dimensional branching models.According models, hydraulic resistance is too large accommodate estimated perfusion brain, unless empties ducts after only several generations (still parenchyma). pressure drops required drive flows same magnitude are not large, but back CSF means that total difference driving both limited local differences among compartments, which be small.Periarterial driven by steady implausible, given current estimates anatomical dynamic parameters.