What are normal variants of neurovascular anatomy relevant to posterior cerebral artery (PCA) stroke?

Updated: Jul 30, 2018
  • Author: Erek K Helseth, MD; Chief Editor: Helmi L Lutsep, MD  more...
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The fetal PCA variant is seen in up to 30% of people, with incidence depending on how the variant is defined. The variant occurs when the P1 segment is congenitally absent or markedly hypoplastic and the PCA arises directly from the ipsilateral internal carotid artery (ICA). This can have diagnostic importance, in that PCA territory stroke may be caused by atheromatous disease of the anterior circulation (ie, ipsilateral carotid bulb atheroma).

The central artery of Percheron variant is uncommon and occurs when the bilateral medial thalamic/rostral midbrain perforators arise from a single trunk from one P1 segment. Occlusion may result in bilateral paramedian thalamic and rostral midbrain infarction. This is an example in which a single cerebral artery supplies bilateral structures.

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