Double vertebral artery-connected persisting proatlantal artery coexisting with a persisting carotid duct in an adult case: first evidence

Abstract Purpose The persistent proatlantal artery represents persistence of the embryonic first cervical intersegmental artery and creates a carotid–vertebral anastomosis. A persisting carotid duct is an exceptionally rare persistence of the dorsal aortic segment between the third and fourth aortic arches. It may be associated with segmental occlusion/stenosis of the proximal external carotid artery. Methods Archived c omputed tomography angiography files in a 62 year-old man were studied anatomically. Results A right-sided persisting carotid duct arising from the subclavian artery with short proximal ECA occlusion/stenosis and reconstitution of the distal ECA was found. A large type II PPA arose from the reconstituted ECA, formed a suboccipital loop giving rise to the occipital segment of the occipital artery, and established two distinct junctions with the vertebral artery: an anterior branch to the V3 segment near the posterior condylar foramen and an inferior branch to the V2 segment immediately before entry into the C1 transverse foramen. Conclusion This configuration provides imaging evidence of a true ‘double-connection’ of a persisting proatlantal artery, coexisting with a persisting carotid duct and proximal external carotid occlusion/stenosis, with potential implications for carotid interventions and posterior-circulation haemodynamics.