A bilateral fetal origin of the posterior cerebral artery coexisting with an absent A1 segment of the anterior cerebral artery.

Background: The cerebral arterial circle variants are well-described due to their clinical significance for neurosurgeons and neuroradiologists.

Materials and methods: This magnetic resonance angiography (MRA) report describes the unusual coexistence of three cerebral variants incidentally identifiedin a 44-year-old female patient.

Results: The right-sided first segment (A1) of the anterior cerebral artery (ACA) was absent, and both the posterior cerebral arteries (PCAs) originated from the internal carotid arteries (ICAs). Thus, the unilateral A1 segment absence coexisted with a bilateral PCA of fetal origin. These variants' coexistence significantly disrupts the patient's primary collateral pathway.

Conclusions: The clinical significance and consequences of such variants after stroke or transient ischemic attack cannot be overstated, underscoring the importance of the current imaging findings in understanding and managing these conditions.