Can a harmless branching pattern of brain arteries look like an aneurysm on a scan?

Details

This single-patient case report describes a woman suspected of having an anterior cerebral artery (ACA) aneurysm who was ultimately found to have an “azygous ACA shield.” This benign finding highlights the importance of thorough investigation with cerebral digital subtraction angiography (DSA).

The 73-year-old woman initially presented with shortness of breath and dizziness. A CT angiogram of the head suggested an incidental 5 mm ACA aneurysm. Subsequent DSA showed a Type I azygos ACA supplied by the left A1 segment. There was also a focal widening of the azygos trunk where it gave rise to the pericallosal and callosomarginal arteries on both sides. Three-dimensional visualization showed that this was a benign widening due to the branching of these four vessels; no aneurysm was seen.

The abstract states that the incidence of aneurysms at the distal dividing point of an azygos ACA ranges from 13% to 71%. Nevertheless, it emphasizes that careful anatomical examination is essential: an apparent aneurysm may instead be a benign widening for which intervention is not indicated.