A perivascular space, also known as a Virchow–Robin space, is a fluid-filled space surrounding certain blood vessels in several organs, including the brain, potentially having an immunological function, but more broadly a dispersive role for neural and blood-derived messengers.

The Virchow–Robin space is a continuation of the subarachnoid space and varies considerably in depth by species

Cisternostomy is a technique that incorporates knowledge of skull base surgery and microvascular surgery. By opening the brain cisterns to atmospheric pressure, the technique could decrease the intracranial pressure due to a backshift of the cerebrospinal fluid, from the swollen brain to the cisterns through the Virchow Robin spaces.

Enlarged Perivascular Space