Imaging description

Developmental venous anomalies (DVAs) are the most common of the cerebral vascular malformations, with an incidence of up to 2.6% in the general population. They are believed to occur as a result of an embryological event that leads to interruption in the normal development of the venous system.

Normal cerebral veins may be anatomically divided into two distinct systems of drainage: superficial (pial, cortical) and deep (subependymal). The absence of development of normal pial or subependymal veins leads to an “anomalous venous disposition,” in which the drainage patterns are reversed [1]. A DVA consists of a radial complex of venous radicles draining normal brain parenchyma that converge into a dilated collecting vein, resulting in its characteristic caput medusae (medusa head) appearance (Fig. 15.1). DVAs of the brain range from a small, single draining vein involving a small portion of the brain, to a large, essentially hemispheric venous anomaly. Contrast-enhanced CT or MRI can identify the collector vein of DVA as a linear or curvilinear focus of enhancement that courses from the deep white matter to a cortical vein or to a dural sinus (Fig. 15.2). Alternatively, the enhancement may course in the opposite direction in a deep draining DVA, in which the intracortical and superficial medullary veins drain toward the deep venous system.