Artery of Percheron, an Uncommon Variant of Posterior Cerebral Circulation: A Case Report

Abstract

The posterior communicating artery (PcomA), P1 and P2 segments of the posterior cerebral arteries (PCAs) give rise to numerous small branches that chiefly supply the thalamus and midbrain. Thalamic vascular supply is classically categorized into four regions: anterior, paramedian, infero-lateral and posterior. Despite significant variations and overlap in the blood supply, this traditional classification helps in understanding the vascular anatomy of the thalamus. Gerard Percheron extensively studied thalamic blood supply and described its anatomical variants depending on its origin. The artery of Percheron (AOP) is a rare anatomical variation of paramedian-mesencephalic arterial supply in which a solitary arterial trunk arises from the PCA and distributes bilaterally to both paramedian thalami and often to the rostral part of the midbrain. During routine dissection of the brain of a 46-year-old female in the department of anatomy, it was seen that thalamo-perforating artery (AOP) took origin as a single trunk from the P1 segment of the left PCA. The specimen was dissected and photographed for documentation and to see more details. The exact prevalence of AOP remains unknown, but various studies show that it can be present in 7% to 11.7% of subjects. Detailed knowledge of AOP anatomical variation is crucial for interpreting neuroimaging results or performing different neuro-endovascular techniques at the basilar bifurcation, particularly in patients with bilateral thalamic and midbrain infarctions.

Keywords: artery of percheron; neuroimaging; posterior cerebral artery; thalamoperforators; thalamus.

Figure 1. Depicts AOP originating from the P1 segment of left PCA.

AOP-Artery of Percheron, BA-Basilar Artery, Lt PCA-Left posterior cerebral artery, Rt PCA- Right posterior cerebral artery, MB- Mamillary body, ICA- internal carotid artery, PcomA- Posterior communicating artery

Figure 2. Variants of thalamic blood supply.

(A) Type I: Both the left (L) and right (R) paramedian arteries (PMAs) typically originate independently from their respective posterior cerebral arteries (PCAs). This is considered the most common type of thalamic blood supply. (B) Type IIa: Both PMAs emerge from either the left (L) or right (R) PCA, deviating from the usual bilateral origins. (C) Type IIb: The artery of Percheron is a specific type where both thalami are supplied by a single branch that can take origin either from the left (L) or right (R) PCA. (D) Type III: Multiple small perforating branches emanate from a singular arterial arc that spans the P1 segments of both PCAs. AN-anterior nucleus, MDN- mediodorsal nucleus, VAN- ventral anterior nucleus, VLN- ventral lateral nucleus, VPN- ventral posterior nucleus, LPN- lateral posterior nucleus, LDN- Lateral dorsal nucleus (Image credit - Dr. Neha Xalxo)