Vascular anatomy is an unreplaceable knowledge for any surgical and interventional specialist, where its proficiency must include at least the most common anatomical variants described in the population. In this subject, aortic arch and its branches are not an exception. The most common anatomical variant of the aortic arch branches is a fourth vessel arising from it, corresponding to the origin of the left vertebral artery. In this case report we describe a patient with an aortic arch branches’ variant plus an intracranial arteriovenous malformation. Up to our knowledge, this is the first case report describing with a proper imaging protocol both a vertebral artery variation and an arteriovenous malformation. Although there is no evidence supporting an association among these two vascular conditions, hereby we present a coincidental vascular finding that requires further research as to propose possible association. Key words: vertebral artery, arteriovenous malformation, aortic arch origin, vascular variant.

In normal conditions, the aortic arch gives rise to the brachiocephalic trunk, the right common carotid artery and the left subclavian artery (LSA). The left vertebral artery (LVA) arises as the first branch of the LSA, from its posterosuperior aspect, 0.5-2 cm medial to the thyrocervical trunk. It is divided into four segments: V1 or ostial segment goes from its origin at the subclavian artery until reaching the transverse foramen of C6; V2 or foraminal segment which traverse through the transverse foramina of C6 to C1; V3 or suboccipital segment courses posterior and superiorly to the posterior arch of the atlas until piercing the atlanto-occipital membrane and duramater; and V4 or intradural segment which joins the contralateral vertebral artery to form the basilar artery. In 1928, Buntaro Adachi , best known for his studies of vascular anatomy and considered the master of vascular anatomical variations, described in his masterpiece “Das Arteriensystem der Japaner”, a variation in which a fourth vessel, an anomalous LVA, arises from the aortic arch, classified as Adachi Type C .