Cervical Arterial Collateral Network

Purkayastha et al reported 3 cases of proatlantal intersegmental arteries of external carotid artery origin associated with Galen’s vein malformation; however, because of their configuration, I believe that the 3 cases do not demonstrate this rare arterial variation, but rather show collateral blood flow from the occipital artery (OA) to the vertebral artery (VA). In patients with a vein of Galen malformation, the intra-arterial blood pressure in the VA is lower than that in the OA because of blood steal phenomenon at the malformation. It is well known that there is a cervical arterial collateral network between OA, VA, and the deep cervical artery arising from the subclavian artery. If one of these arteries is occluded, the remaining arteries and their branches are dilated and supply the distal segment of the occluded artery. The 3 cases reported by Purkayastha et al have a similar condition to proximal VA occlusion and therefore should not be considered proatlantal arteries.