These prominent venous structures at the left parietal region along with prominent dilated draining vein and normal related brain parenchyma are likely representing developmental venous anomalies.

Developmental venous anomalies (DVA) represent variations of normal venous drainage rather than true malformations. They are usually asymptomatic. They consist of tortuous tributary veins that converge on an enlarged draining vein giving a "caput medusae" appearance.