Objective:

Describe two cases of persistent trigeminal artery (PTA) presenting with ischemic stroke and highlight how PTA recognition influences diagnosis and long-term management.

Background:

PTA is a persistent embryologic carotid–basilar anastomosis, connecting the cavernous segment of the internal carotid artery to the posterior circulation. Found in <1% of the population, PTA can provide collateral flow when the vertebrobasilar system is hypoplastic. PTA is also associated with vascular nerve compression syndromes, posterior circulation ischemia, and aneurysm formation. PTA types according to the Saltzman classification are, Type I: PTA supplies the distal vertebrobasilar and is typically associated with hypoplastic caudal basilar/distal vertebral arteries; Type II: PTA supplies superior cerebellar arteries (SCAs) while posterior cerebral arteries (PCAs) are supplied by robust posterior communicating arteries; Type III: PTA does not join the basilar trunk but terminates directly as a cerebellar artery.

Design/Methods:

Case Report

Results:

Case 1: A 67-year-old female with dyslipidemia presented with acute vertigo, nystagmus, and emesis. CT angiogram was concerning for mid-basilar occlusion; however, cerebral angiogram (DSA) revealed a right PTA supplying the distal basilar artery, PCAs, and SCAs, with hypoplastic vertebral contribution. MRI showed scattered infarcts in the right cerebellum and parietal lobe, suggesting an embolic source. Case 2: A 64-year-old male with hypertension, tobacco and polysubstance use presented with right MCA infarct. DSA demonstrated right-sided critical distal M1 stenosis and a right PTA filling the SCAs and PCAs bilaterally, suggesting possible flow limiting ischemia to the MCA territory. A 2mm right paraclinoid ICA aneurysm was also noted.

Conclusions:

PTA can predispose to stroke through embolic transfer from the anterior to posterior circulation, flow-related insufficiency, or in situ thrombosis, and is associated with aneurysm formation due to altered hemodynamics. Recognition of PTA has direct implications for stroke diagnosis and mechanism, impacts management decisions, and underscores the need for careful vascular surveillance.