MICROSURGICAL ANATOMY AND CLINICAL-SIGNIFICANCE OF THE ANTERIOR COMMUNICATING ARTERY AND ITS PERFORATING BRANCHES

OBJECTIVE: Precise identification of the anomalous anterior communicat ing artery (ACoA) or the perforating branches of the ACoA is usually d ifficult on preoperative angiograms because of the vascular complexity around the ACoA and its small-caliber branches. The purpose of this s tudy was to review the microsurgical anatomy of the ACoA and its branc hes to show their importance for the interhemispheric trans-lamina ter minalis approach and ACoA aneurysmal surgery. METHODS: In 30 cadaver b rains, the ACoA and its branches were examined under magnification usi ng a surgical microscope. RESULTS: The ACoA was evident in all specime ns and had variations consisting of plexiform (33%), dimple (33%), fen estration (21%), duplication (18%), string (18%), fusion (12%), median artery of the corpus callosum (6%), and azygous anterior cerebral art ery (3%). The perforating branches were also observed in all cadaver b rains. They were classified into subcallosal, hypothalamic, and chiasm atic branches according to their vascular territories. The subcallosal branch, usually single and the largest, supplied the bilateral subcal losal areas, branching off to the hypothalamic area. The hypothalamic branches, multiple and of small caliber, terminated in the hypothalami c area. CONCLUSION: The incidence of anomalous ACoA was higher than ha s been previously reported, and any segment of the anomalous ACoA may have perforating branches regardless of diameter. Among the three bran ches, the subcallosal branch is the most important because it feeds bi lateral subcallosal areas branching to the hypothalamic area.