Expanding Virchow Robin spaces in the midbrain causing hydrocephalus.

We describe a patient who showed cystic lesions in the midbrain and obstructive hydrocephalus. MR imaging features corresponded to abnormal dilatation of perivascular spaces. Similar clinical and MR imaging findings were described in previous reports of patients presenting with mesencephalo-thalamic expanding lacunae; the diagnosis of some of those cases was confirmed at postmortem examination This condition is extremely rare but should be part of a differential diagnosis when evaluating cystic abnormalities in this area of the brain.