Abstract:

　　Objective: To present a surgical strategy dealing with the distal anterior cerebral artery aneurysm(DACAA) by the microanatomy of distal anterior cerebral artery, focusing especially on the relationship between the pericallosal artery (PerA) and callosomarginal artery (CMA) located in the lower half of the A3 (infracallosal) segment. Methods: The microsurgical anatomy of the distal anterior cerebral artery region was examined on 20 adult cadaveric cerebral hemispheres after perfusing of the arteries and veins with colored silicone. The relationships of the infracallosal segment of the PerA to the CMA and the A2 segment of the PerA to the frontopolar artery were examined. The distance between the nasion and the site at which a parallel line directed along the long axis of the infracallosal PerA just proximal to the origin of the CMA artery crosses the forehead (which we have named the PC point) was also measured. In addition, the surgical approaches to DACAA were examined in stepwise dissections. Results: The pericallosal-callosomarginal artery junctions located at the supracallosal and infracallosal segments of A3 in accounting for 55 and 45% of cases, respectively. In the infracallosal region, it was difficult to gain proximal control of the artery with the tumor on it. The PC point was, on average, 31.52 mm and 34.64 mm away from the nasion in cadaveric cerebral hemispheres and T2RMRI, respectively. There was only a limited space in which to gain access to infracallosal DACAA below the PC point to establish proximal control by the anterior interhemispheric approach. Conclusions: When the approach is made above the PC point, an anterior callosotomy might be necessary to establish proximal control before final aneurysm dissection and clip placement is completed. The PC point is an important surgical landmark in planning the surgical strategy for treating infracallosal distal DACAA.

Key words: distal anterior cerebral artery aneurysm, interhemispheric approaches, microsurgical anatomy, surgical strategies