Left type I proatlantal artery with bilateral aberrant vertebral arteries and a ruptured aneurysm: a case report and review of the literature

Persistent proatlantal artery is one rare kind of persistent primitive anastomoses between carotid and basilar vascular system. This case firstly introduces a type I proatlantal artery with complex vascular anomalies of bilateral vertebral arteries and a ruptured aneurysm, which is extremely uncommon. A 43-year-old female was hospitalised for SAH and ventricular hematocele. The subsequent digital subtraction angiography and computed tomography angiography revealed a type I proatlantal artery which arises from left internal carotid artery, associating with a hypoplastic right vertebral artery, an aplastic left vertebral artery and a ruptured left posterior inferior cerebellar artery aneurysm. An interventional procedure was taken later. The present case raises awareness on the incidence of persistent primitive anastomoses which combined other complex vascular anomalies before surgical or interventional procedures, especially in view of unique blood supply to posterior circulation from the primitive vessel.