Developmental venous anomalies are the most common vascular malformation seen at autopsy, with an incidence of 2.6%. Histologically, they consist of dilated, radially arranged, thin-walled venules separated by normal brain that drain into an enlarged collecting vein. They are typically located in the deep cerebral or cerebellar white matter, usually near the margin of an adjacent ventricle. They are most commonly found adjacent to the frontal horn of the lateral ventricle, with the cerebellum the second most common site. The lesions are typically solitary, with multiple seen in “blue rubber bleb nevus syndrome” (characterized by bluish discolored skin, mucocutaneous lesions, multiple venous angiomas, and sinus pericranii (an unusual venous anomaly characterized by communication of pericranial varicosities with an underlying dural sinus)).

The majority of developmental venous anomalies are aysmptomatic, typically discovered incidentally on autopsy or on imaging studies. Headache, seizures, and neurologic deficits are less common.

On cerebral angiograms, the appearance has been likened to a “Medusa head”. The appearance is radiographically diagnostic, with dilated medullary veins converging on an enlarged transcortical vein. They demonstrate superficial venous system drainage in 70% and subependymal drainage in 22%. Uniform enhancement is typical. Evidence of gliosis or hemorrhage is seen in 10-15%.

Since the developmental venous anomaly represents drainage of normal brain parenchyma, these are typically only surgical lesions when misdiagnosed, since thrombosis or removal of the lesion can produce venous infarction.