Figure 11: Cerebral angiography (lateral view) with injection of the left vertebral artery (arrow) shows occlusion of the basilar artery (open arrow) at the vertebrobasilar junction, just above the origin of the right superior cerebellar artery (white arrowhead). There are many tiny collaterals that supply the territory of the brainstem perforators (small arrowheads) and wider collaterals that reconstitute the superior cerebellar artery (asterisks). There is also retrograde filling of the right vertebral artery (white arrows) and of the right PICA.