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Giant saccular aneurysm of the distal A2 segment of the azygos anterior cerebral artery. Difficulties in surgery

Azygos artery (a. azygos) in the anterior cerebral artery A2 segment is a rare anatomic anomaly, as well as giant saccular aneurysm in the A2 segment of the a. azygos trunk. Giant aneurysm of the azygos A2 segment artery is incidental, and thus far literature has reported only a small number of cases, treated surgically after the subarachnoid haemorrhage. The literature also provides a description of the coexistence of an azygos artery with corpus callosum hypoplasia, porencephalia, or vascular malformation [1–4]. In my own extensive (material subsequently treated by clipping and reviewed patients after subarachnoid haemorrhage within the last 10 years, no case of an azygos anterior artery A2 segment and coexisting giant aneurysm has been found. Differentiating the anatomic type between azygos artery and paired vascular system based on brain arteriography after subarachnoid haemorrhage is difficult due to the asymmetry of paired vessels, uneven contrast enhancement, and the possibility of vasospasm after subarachnoid haemorrhage. Angiography may suggest anomaly. Final verification is possible during the surgical approach and exposure of the vessels during the preparation of the main vessel in longitudinal fissure of the brain. I encountered this problem during my clinical practice. Initially, computed tomography (CT) examination revealed a pathological mass in the longitudinal fissure and blood collection in the regional subarachnoid space. Angiography revealed a giant aneurysm of the A2 segment located slightly above the genu of corpus callosum, and this triggered speculation as to the type of pericallosal artery anomaly, e.g. high division of pericallosal arteries, azygos artery, left pericallosal artery hypoplasia, or spasm of the vessel (Figures 1, 2). It was an urgent clinical situation on surgical duty. After angiography we discussed firstly about embolisation of the aneurysm because we have good cooperation with my colleagues from radiology. Finally, we decided to perform surgery because the aneurysm was giant with a wide neck, and it was Figure 1. Angiography examination of giant aneurysm before operation