Some new research by the group of scientists at the University of Rochester who discovered the glymphatic system; the system cleans debris from our brains when we are deeply sleeping (non-REM slow wave sleep): Immediately after a stroke, the known swelling of the brain that occurs -- and greatly enhances the likelihood of immediate death -- is caused by cerebral spinal fluid (not plasma, as previously thought) coursing into the brain. The details are in the brief article below, including a video.
-- Saul
https://newatlas.com/medical/waste-removal-system-drown-brain-stroke/