ANATOMIC VARIATIONS A case of a type II proatlantal artery with arteriovenous malformation L. A. Arra ´ez-Aybar • P. Navia-A ´ lvarez • J. C. Me ´ndez-Cendo ´n Received: 4 September 2009 / Accepted: 28 May 2010 / Published online: 12 June 2010 Ó Springer-Verlag 2010 Abstract We describe a 64-year-old woman evaluated with angiography a case of persistence of a proatlantal artery (type II) with an arteriovenous malformation asso- ciated to the posterior cerebral artery. This association has been reported once in the literature consulted. The proat- lantal artery arises from external carotid artery, cranial to the origin of facial artery at the level of C4 vertebra, anteromedial to the internal carotid artery, laying on it during its course cranial, lateral and posterior. After mak- ing a loop at the level of the transverse process of C3 vertebra, it enters into the transverse foramen of C3 ver- tebra and continuing its course, through the transverse foramen of C2 and C1 vertebra, as vertebral artery. Winds behind the superior articular process of the atlas enters the skull through the foramen magnum and, at the lower border of the pons, joins with the vessel of the opposite side to form the basilar artery. The internal carotid artery is nor- mal. This variation is associated with congenital arterio- venous malformations that represent the persistence of an embryonic pattern of congenital vessels. Keywords Carotid-vertebral anastomoses Á External carotid artery Á Vertebral artery Á Basilar artery Á Arterial variations Introduction Proatlantal artery (PA) is a remnant of one of the primitive channels that supplies communication between the carotid (anterior) and vertebrobasilar (posterior) circulatory sys- tems for a short period of time during embryonic life. Rarely, these anastomoses will persist into adult life these are typically identified serendipitously. In 1885 Gottschau [see 26], at autopsy, has made the first anatomical description of a PA, arising from the internal carotid artery (ICA). Froriep in 1886 [5], Hochstetter in 1890 and Schemeidel in 1932 [see 26] were, respectively, the first in observing and interpreting correctly the PA in bovine, rabbit and human embryo. Sutton in 1962 [see 22] has made the first angiographical description. However, Abe and Suzuki in 1964 [see 15] were the first to identify this anomalous vessel as the PA. The incidence is between 0.1% of the carotid endarterec- tomies and the 0.023% of the cerebral angiograms [28]. Lucarelli and de Ferrari [12], Flynn [4] and Hackett and Wilson [7] could find a variant of PA, that arose from the external carotid artery (ECA), this leads Lie [11] to acknowledge two types of PA those arising from the ICA (which he called intersegmental proatlantal artery) and those arising from the ECA (which he called primitive Proatlantal artery), that Lasjaunias et al. [9] denominate, respectively, ‘‘Proatlantal artery type I’’ and ‘‘Proatlantal artery type II’’. Nowadays some authors [9, 26] consider that type I PA begins either from the ECA or the ICA or the common L. A. Arra ´ez-Aybar (&) Department of Human Anatomy and Embryology II, Faculty of Medicine, University Complutense Ciudad Universitaria s/n, 28040 Madrid, Spain e-mail: arraezla@med.ucm.es L. A. Arra ´ez-Aybar Á P. Navia-A ´ lvarez Institute of Morphofunctional Sciences, University Complutense Ciudad Universitaria s/n, Madrid, Spain J. C. Me ´ndez-Cendo ´n Department of Radiology, Hospital Ramo ´n y Cajal, Madrid, Spain 123 Surg Radiol Anat (2011) 33:85–89 DOI 10.1007/s00276-010-0685-6