Azygos anterior cerebral artery

Case contributed by Dr Safwat Mohammad Almoghazy


A known case of gastric GIST. Postoperative decrease conscious level investigated with an urgent CT brain.

Patient Data

Age: 60 years
Gender: Female

Incidentally noted small but present A1 segment of the left anterior cerebral artery. The left and right A1segments join to form a single trunk making an azygos anterior cerebral artery (rare normal variant), before branching into normal branches. 

No evidence of acute brain insult. 

Annotated image

Annotated images. 

Case Discussion

An azygos anterior cerebral artery is an uncommon-to-rare variant of the circle of Willis where the two A1 segments of the anterior cerebral artery (ACA) join to form a single trunk. As a result, there is no anterior communicating artery. This organization is similar to that seen in lower primates.

The clinical importance of an azygos artery:

  • may be associated with a number of brain anomalies such as dysgenesis of corpus callosum and holoprosencephaly, and a predisposition to aneurysm formation
  • an occlusion of an azygos artery may result in infarcts of the bilateral medial frontal lobes and corpus callosum


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Case information

rID: 51987
Published: 21st Apr 2017
Last edited: 22nd Apr 2017
Inclusion in quiz mode: Excluded

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