Bilateral Type 1 Proatlantal Arteries with Absence of Vertebral Arteries

Summary: The persistent proatlantal artery is a well-de-scribed communication between the carotid and vertebro-basilar system. However, persistence of bilateral proatlan-tal arteries is exceptionally rare. Although usually noted as an incidental finding, the presence of a proatlantal artery, particularly when bilateral, may result in unusual symp-toms or may have implications for therapy. We report a case of bilateral proatlantal arteries, describe their embry-ology, and consider potential clinical implications of this finding. Communications between the carotid and verte-brobasilar system are well-recognized anomalies. One such communication, the persistent proatlantal artery, was first described at autopsy in the 19th century (1). Since that time, more than 40 case