Perivascular Spaces
Perivascular spaces are microscopic channels surrounding brain blood vessels that enable cerebrospinal fluid flow and waste clearance. They are functional structures in healthy tissue, not empty voids or signs of damage.
Perivascular spaces are microscopic channels that surround blood vessels in the brain, serving as critical conduits for the movement of cerebrospinal fluid and waste clearance via the glymphatic system. They are not pathological voids but functional anatomical structures present in healthy individuals, essential for maintaining brain homeostasis. Modern MRI techniques, including phase-contrast imaging and fluid-sensitive sequences, allow researchers to visualize flow dynamics within these spaces, though methodologies remain non-standardized across research groups.
What this means in real life
When you sleep, your brain cells shrink slightly, widening these channels around blood vessels so fluid can flush through and carry away proteins like amyloid-beta that accumulated during waking hours.
What it isn’t
These are not blood vessels themselves, nor are they the same as the blood-brain barrier. They are separate fluid-filled spaces that exist around vessels, distinct from the vessel walls or the general cerebrospinal fluid in the ventricles.
Commonly misused online
Often conflated with the glymphatic system itself; actually, perivascular spaces are one component of the glymphatic system, not synonymous with it. Some posts treat them as newly discovered, though they've been known for over a century.