Dual fenestration of the A1 and azygos A2 segments of the anterior cerebral artery illustrated by Magnetic Resonance Imaging.

purposeFenestrations are probably the most common among the anomalies of intracranial arteries. They are known for their association with other vascular conditions, such as aneurysms and arterio-venous malformations. Anterior cerebral artery (ACA) in both A1 and A2 segments is subjected to many anomalies, including fenestrations, but they are rarer than hypoplasia and aplasia. The association of more than one anomaly has been described, but the presence of a dual fenestration in a single arterial segment has been anecdotally reported.

methodsA case of an incidentally discovered association of two ACA anomalies, i.e. dual fenestration in the A1 segment and azygos pattern in the A2 segment, is presented. Both anomalies were identified in a brain Magnetic Resonance Imaging (MRI) study with MR Angiography. The clinical indication for MRI was tinnitus. The other intracranial arteries were unremarkable (apart from duplicated posterior communicating arteries) and the brain parenchyma did not show abnormalities. No aneurysms were found.

conclusionsThe reported anomalies (the dual fenestration and the azygos A2 ACA) are located in the same arterial territory and potentially have a long-term effect on the local hemodynamics of the ACA facilitating the formation of aneurysms. Then, an imaging follow-up may be adviced.