Abstract
Distal anterior cerebral artery (DACA) aneurysm accounts for 6‐8% of all intracranial aneurysms. DACA was divided in four segments (A2‐5) by Dashi. We modified that aneurysm of A2 segment extends from the fronto-orbital artery branch origin to the border between rostrum and inferior genu, which is called infracallosal aneurysm. The A2 segment of DACA accounts for 8‐10% of all DACA. There are almost no detailed descriptions of infracallosal aneurysms in the literature. Infarcallosal aneurysms in five of our cases revealed a few features. The first was that the dome of the aneurysm in four of five cases projected posteriorly and superiorly. The second was that aneurysms in three cases were not associated with the branch on the A2 trunk. Two of the five cases were complicated with azygos artery or fenestration. Furthermore, almost all aneurysms had a relatively broad neck. It is very difficult to occlude infracallosal aneurysms because the A2 segment is in the deepest portion of the DACA running and tight between both inner frontal lobes.
A wide working space for the approach to the infarcallosal aneurysm should be maintained when using the basal anterior and distal interhemispheric procedure.
