Diagnostic Pitfall: Atypical Cerebral Venous Drainage via the Vertebral Venous System

Summary: We report a case of atypical cerebral venous drainage in a 38-year-old woman with symptoms of benign paroxysmal positional vertigo. Thrombosis of the left inter-nal jugular vein and sigmoid sinus was suspected on the basis of spin-echo and time-of-flight MR findings, but mul-tisection CT angiograms showed a patent sigmoid sinus and predominant drainage via the emissary veins toward the vertebral plexus, with only a minor contribution of the jugular veins. This case illustrates the variability of the venous anatomy in the craniocervical region. Internal jugular vein (IJV) and sigmoid sinus thrombosis was suspected because of the following: 1) absence of flow-induced signal alterations on MR images, 2) apparent collateral flow through strongly dilated intraspinal and vertebral veins, and 3) lo