Background. The anterior communicating artery (ACoA) complex consists of the ACoA, the pre-and post-communicating segments of the anterior cerebral artery, and the recurrent artery of Heubner. It is the most common site for anatomical variations in the circle of Willis. Such variations can mimic intracranial aneurysms. Case description. A 30-year-old female presented with recurrent episodes of extreme headache and bilateral tinnitus. A brain computed tomography (CT) scan showed no significant lesions, while her CT-angiography (CTA) showed an enlarged vascular lesion at the ACoA, raising the suspicion for an ACoA aneurysm. A repeated CTA revealed a rare anatomical variation with a pattern of cross dominance in the ACoA complex; the left A1 and right A2 were dominant-enlarged, resulting in an enlargement of the ACoA. The presence of an ACoA aneurysm was hence excluded and the patient was managed conservatively. At 6-month follow-up, CTA showed no new findings. Conclusion. ACoA enlargement can result from unequal hemodynamics around the ACoA complex, which may be mistaken for an aneurysm. A thorough study of the imaging data is of pivotal importance and may change the management strategy.
