Multiple variations in vertebrobasilar system: A cadaveric study

The intracranial parts of the vertebral arteries (VAs), basilar artery (BA) and their branches together form the vertebrobasilar system (VBS). Numerous anomalies have been seen in VBS, which are usually benign. Many authors have reported unilateral hypoplasia of VAs, posterior and anterior inferior cerebellar arteries and variation in origin of branches of VA and BA. These are thought to develop due to some errors during development. Aplasia of VA is a common variant but seldom reported. During routine dissection a rare variant of VA along with multiple variations in other arteries of vertebrobasilar system was observed in one cadaveric brain. It was observed that there was aplasia of left VA and left PICA took origin from the right VA, crossed midline and supplied the contralateral side of the cerebellar hemisphere. Double origin of right anterior inferior cerebellar artery (AICA) and bilateral fetal PCA (posterior cerebral artery) was also observed.