Anatomical variations of the carotid-vertebral arteries: "double-vessel" sign on Doppler ultrasonography.

We describe the "double-vessel" sign and its relevance for the diagnosis of carotid and vertebral arterial anatomical variations in a series of four patients with stroke. In these four patients, two arteries could be seen at the expected location of the common carotid artery (CCA), leading to the diagnosis of anatomical variations including separate origin of internal and external carotid artery from the aortic arch on the left side and from the brachiocephalic trunk and the subclavian artery on the right side, early bifurcation of the CCA on both sides, and an aberrant course of the vertebral artery on the left side. The presence of two arteries at the expected location of the CCA should raise the suspicion of carotid or vertebral arterial variations.