Human basilar artery abnormalities in the prenatal and postnatal period

Although complex and varied, adult cerebral angioarchitecture has its origins in embryologic development, where normal components, variations, and abnormalities evolve from modifications of primitive vessels. Therefore, the aim of this report was the study of the morphologic features of the basilar fenestrations in prenatal and postnatal period and associated variants and/or pathologies.

We studied the brain vessels of 120 fetuses microscopically (i.e., with an operative microscope) and 112 adult cadavers macroscopically.

We described 10 cases of basilar abnormalities, five fetal and four adult fenestrations, as well as one adult case with a basilar aneurysm. The location of the vertebrobasilar junction on a caudal myelencephalon and a prolongation of the basilar trunk followed both fetal and adult forms of fenestrations. The same caliber values of the basilar and internal carotid arteries, a variation in the number and origin of some of the basilar side branches, and a tendency of fenestrations to be multiple in number, as particular fetal features, were mostly present in adults.

The fact that basilar fenestrations in adult specimens shared similar features with fetal ones and without aneurysms, as well as the fact that a basilar aneurysm was without fenestration in its base, lead us to hypothesis that the basilar fenestration is a vascular developmental variant related to the maintenance of vascular symmetry in the midline of the human brain base.