Perivascular (Virchow-Robin) spaces

What it means

Small blood vessels supplying the deep parts of the brain are surrounded by a thin, fluid-filled cuff as they dip inward from the brain's surface, and this cuff is called a perivascular space, or Virchow-Robin space after the two scientists who first described it. These spaces are part of the brain's normal plumbing, thought to play a role in clearing waste fluid from brain tissue, similar in concept to the lymphatic system that drains other parts of the body.

Why it appears on a CT or MRI report

Perivascular spaces are seen on essentially every brain MRI, since they are a completely normal part of brain anatomy, and radiologists mention them in a report mainly to note when they are more numerous or slightly larger than typical for a person's age, or to distinguish them from other small findings such as tiny strokes. They typically appear as small, round or linear structures that follow the same signal pattern as cerebrospinal fluid on every imaging sequence, most often clustered near the base of the brain, along the pathway of the small deep arteries, and in the white matter above the ventricles.

What it usually means

Perivascular spaces are visible on MRI in nearly everyone and become both larger and more numerous with normal aging, so finding them, even in fairly large numbers, is usually not a sign of disease on its own. Because they follow fluid signal exactly and sit in predictable locations along blood vessels, radiologists can generally distinguish them confidently from more concerning findings like small strokes, which have a different signal pattern and don't follow the same vessel-tracking pattern.

In some situations, a notably higher number of prominent perivascular spaces has been loosely associated with high blood pressure, small vessel disease of the brain, or, rarely, certain inherited conditions, but this is generally only considered meaningful when the pattern is unusually extensive or paired with other findings and symptoms, not from the presence of perivascular spaces alone.

When to follow up

In the vast majority of cases, perivascular spaces mentioned on a report require no follow-up or treatment at all — they are simply being documented as part of a complete, accurate description of the scan. If your report specifically flags an unusually large number of them, or pairs the finding with other changes such as small vessel disease or white matter changes, it is reasonable to discuss this with your doctor, particularly if you have risk factors like high blood pressure, since managing those risk factors is generally the relevant next step rather than any action targeted at the spaces themselves.

A plain-language way to picture it

Picture the deep blood vessels of the brain as tiny pipes running through the tissue, each wrapped in a thin sleeve that carries away a trickle of fluid, much like the narrow drainage channel that sometimes runs alongside a buried water pipe. Everyone has these little sleeves, and most people accumulate a few more of them, sometimes a bit larger, as the years go by — a normal sign of a well-used system rather than evidence that anything has gone wrong with it.