Neuroradiology

Proatlantal arteries, intersegmental

very rare persistent embryonal anastomoses (usually single, primitive cervical segmental arteries) that connect the internal or external carotid artery with the ipsilateral verteral artery before the latter traverses the foramen magnum. The distal course of the vertebral artery and basilar artery in these instances is normal whereas the proximal segment of the vertebral artery may be atretic.

Angiograms of the common carotid artery demonstrate the entire posterior circulation of the brain and the circulation of the ipsilateral hemisphere (see carotidovertebrobasilar anastomosis persistent).

GS