Rare Neurovascular Variants Arising from the Internal Carotid Artery

We reviewed rare cervical and intracranial ICA anatomic variants, aberrant ECA origins; aberrant or aplastic ICAs; CCA absence; persistent proatlantal, stapedial, hypoglossal, and trigeminal arteries; primitive maxillary and mandibular arteries; and duplicated posterior communicating arteries, including a persistent primitive fetal branch or hyperplastic anterior choroidal artery, infraoptic anterior cerebral artery, and dorsal-ventral ophthalmic arteries. Variants of the ICA are rare, typically asymptomatic, and incidental findings. However, these variants can occasionally influence surgical or endovascular strategies, temporary occlusion times, inadvertent embolization risk, and collateral pathways, with a potential impact on procedural complications and patient outcomes.

Learning Objective: Review anatomic variations of the internal carotid artery (ICA), including imaging appearances, embryologic development, prevalence, and associations of clinically relevant variants with neurovascular pathology.