An unusual variant of the callosomarginal artery from the A1 segment of the anterior cerebral artery.

BACKGROUND

Although the anatomy of the A1 segment of the anterior cerebral artery (ACA) is highly variable, a callosomarginal artery (CMA) arising from the A1 segment of the ACA is rare.

CASE DESCRIPTION

A 27-year-old man presented with severe headache and was admitted to our hospital. Initial computed tomography (CT) showed subarachnoid hemorrhage in the basal cistern. Three-dimensional CT angiography revealed a saccular aneurysm arising from the left internal carotid bifurcation and showed an anomalous cortical branch originating from the left A1 segment of the ACA. The anomalous artery was interpreted as a CMA.

CONCLUSIONS

Recognizing this variant preoperatively could be helpful in preventing complications of surgery. Careful follow-up studies are necessary in the present case to monitor the development of another aneurysm at the junction between the left CMA and the left A1 segment of the ACA.