An adult right-sided vascular constellation in which a persisting carotid duct reconstitutes the distal external carotid artery and a type II persisting proatlantal artery connects that system to both V3 and V2 segments of the vertebral artery.
The double connection occurred in the same case as a persisting carotid duct and short proximal ECA non-opacification/critical stenosis, creating a developmentally unusual and haemodynamically important collateral network.
Archived head-and-neck CTA from a 62-year-old man was reconstructed with multiplanar, maximum-intensity-projection, and 3D volume-rendering techniques.
Adult male case.
Vessel calibre reported at its subclavian origin.
Non-opacified segment interpreted as critical stenosis/occlusion.
Large vessel arising from the reconstituted distal ECA.
Use the buttons to highlight each functional segment of the collateral system.
The report includes morphometric distances that help anchor the unusual pathway in the upper neck and suboccipital region.
Distance from subclavian origin to the vertebral artery origin.
Distance distal to the vertebral artery origin on the subclavian artery.
PPA crossed the atlas transverse process 34 mm inferior to the mastoid tip.
Superior loop contacted the mastoid 0.52 cm lateral to the occipitomastoid suture.
Anterior PPA branch joined V3 posteroinferior to the posterior condylar foramen.
Descending PPA limb reached 0.59 cm posterior to V3 before dividing.
The authors distinguish a developmental vessel pattern from ordinary muscular collateralisation around the vertebral artery.
The vessel arises from the reconstituted distal ECA, forms a defined suboccipital loop, contributes the occipital artery segment, and joins the VA at two separate sites.
The short proximal ECA non-opacification is interpreted as most likely acquired critical stenosis/occlusion in this 62-year-old; the pre-existing persisting carotid duct then functions as an important feeder of the distal ECA.