On DSA, there is no evidence of ruptured intracranial aneurysm and no clinoid/supraclinoid left ICA aneurysm. A persistent trigeminal artery (PTA) is demonstrated, which is the dominant supply of the basilar artery and bilateral SCA/PCAs, with reflux in the proximal diminutive vertebrobasilar system. A 7-mm multilobulated semi-saccular, semi-fusiform aneurysm involving the origin of the PTA is demonstrated.