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The artery of Percheron is a rare anatomical variant in which a single dominant perforating artery arises from one P1 segment of the posterior cerebral artery (PCA) and supplies bilateral paramedian thalami with or without involvement of the rostral midbrain.

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• It was first described by French neurologist Gérard Percheron.
• It is a classic stroke syndrome, often underrecognized.

Anatomy & Variants

• Normally, thalamic–midbrain perforators arise bilaterally from both PCAs.
• In the AOP variant, one common trunk supplies both sides.

Four main variants of thalamic–midbrain arterial supply (Percheron classification):

1. Type I: Each PCA gives off its own perforators (most common).
2. Type IIa: Both thalami supplied by branches from one PCA.
3. Type IIb (classic AOP): Single unpaired trunk from one PCA bifurcates to supply both thalami.
4. Type III: Arterial arcade between both PCAs provides supply.

Clinical Importance

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Occlusion produces bilateral thalamic infarcts, with hallmark features of altered consciousness, memory dysfunction, and vertical gaze palsy.

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Symptoms:

• Altered consciousness (diencephalic involvement).
• Memory impairment, confusion, hypersomnolence.
• Vertical gaze palsy, oculomotor disturbances.
• Sometimes hemiparesis or cerebellar signs (if midbrain also involved).