Abstract
A thorough understanding of the microanatomy of the basilar artery and its perforators is important for the surgical treatment of basilar trunk aneurysms. Therefore, 25 cadaver brains were dissected and their anatomies were observed under an operating microscope. The findings are given below. On the average, 20.5 (±3.1) small branches, consisting of 12 (±2.2)) median branches and 8.4 (±1.9) circumferential branches, originated from the basilar artery. The median branches were distributed rather evenly, whereas the distribution (and number) of the circumferential branches varied, depending on how the anterior inferior cerebellar artery (AICA) and the superior cerebellar artery (SCA) had developed. In clinical cases that showed a poorly developed AICA and SCA on angiography, the blood supplying the brain stem was found to depend on the circumferential branches, so that when surgically treating such cases, particular attention should be paid to preserving the circumferential branches. Further, fenestration of the basilar artery was seen in two specimens, and since the number of perforators from the fenestrated portion of the basilar artery was found to be the same in brains without this anomaly, trapping of the fenestrated portion should be preferably avoided so as to preserve the perforators.
