The Role of the Primitive Lateral Basilovertebral Anastomosis of Padget in Variations of the Vertebrobasilar Arterial System

Purpose: The primitive lateral basilovertebral anastomosis (PLBA) is an embryonic longitudinal anastomotic channel that transiently interconnects the developing branches of the vertebrobasilar system. This study reviews the anatomy of the PLBA and describes several variants associated with its partial persistence. Methods: Four types of vertebrobasilar anomalies linked to the PLBA are illustrated by 13 angiographic observations. Results: The angiographic appearances of (i) typical and atypical persistent trigeminal artery variants, (ii) common trunks of origin for one, two, or three cerebellar arteries, (iii) aberrant origins of the cerebellar arteries, and (iv) vertebrobasilar duplications are described. The PLBA is the cranial continuation of the ascending ramus of the dorsal radicular branch of the proatlantal artery (i.e., the radicular artery of C1) and represents the cranial equivalent of the posterior-lateral spinal artery. Conclusion: Several previously ill-defined or misunderstood variations of the vertebrobasilar system can be explained by partial persistence of the PLBA. Anat Rec, 2017.