The persistent proatlantal artery: types and subtypes
A nomenclature-focused review of the rare persistent proatlantal artery, arguing that classification should be driven primarily by cervical course and C1 transverse-foramen relationship rather than by arterial origin alone.
Origin alone is insufficient.
The traditional “Type I = ICA / Type II = ECA” shorthand breaks down in hybrid cases. A course-forward approach—especially whether the channel traverses the C1 transverse foramen—better separates canonical Type I, Type II spinal, and Type II occipital/mixed configurations.
Course first, origin second
Select a configuration to compare origin, course, transverse-foramen relationship, vertebral-artery connection, and occipital-artery behaviour.
Separate origin from course
The review proposes a harmonised reading of the literature by documenting both the carotid-system origin and the actual cervical pathway.
Four descriptors reduce ambiguity
The paper recommends a standardised report rather than a one-word label.
Origin
ICA, ECA / occipital system, or CCA.
C1 transverse foramen
Traversed or bypassed.
Occipital artery
Record incorporation, shared trunk, or branch origin.
VA / posterior supply
Document ipsilateral VA status and whether posterior circulation depends on the PPA.
An ECA-origin Type II, occipital subtype
The illustrative CTA case demonstrates exactly why origin-only naming fails.
Patient age
A 73-year-old woman.
Origin
The PPA arose from the posterior aspect of the left external carotid artery opposite C2/C3.
Course
It bypassed the C1 transverse foramen, gave rise to the occipital artery, continued as V3, and entered via the foramen magnum.
Why recognition matters before intervention
A PPA may be a minor collateral or the dominant posterior-fossa supply.
ECA ligation / embolisation
Potentially dangerous when an ECA-derived PPA contributes substantially to the posterior circulation.
Carotid endarterectomy
Carotid flow manipulation may endanger posterior circulation when the PPA is dominant.
CVJ / skull-base surgery
Suboccipital and C1-related variants can lie directly in operative corridors.
Endovascular access
The PPA can occasionally serve as the only feasible route to posterior circulation lesions.