Enlarging Perivascular Spaces Following Radiation Therapy in the Brain: A Report of 2 Cases and Literature Review

Background: Virchow-Robin or enlarged perivascular spaces (PVS) are benign pial-lined spaces that surround penetrating arteries and arterioles through the brain parenchyma. We present 2 cases of enlarging PVS in adults following whole-brain radiation therapy. Case Description: Two patients underwent whole-brain radiation therapy for adult-onset medulloblastoma. Neither patient had enlarged PVS at the time of radiation treatment. The patients presented with PVS in the basal ganglia 6 and 8 years following the completion of radiation, respectively. One patient subsequently showed a decrease in size of PVS over time. Neither patient experienced symptoms, required surgical intervention, or had signs of tumor recurrence. Conclusions: Enlarging PVS can occur years after radiation therapy to the brain parenchyma. Recognition of these benign PVS is important so as not to mistake the changes for more sinister pathology that could lead to unnecessary intervention. Moreover, focal cystic changes more frequently seen surrounding areas of focal brain radiation therapy might represent enlarged PVS.