Fenestration of the double origin of the posterior inferior cerebellar artery associated with a contralateral vertebral artery dissection.

Double origin of the posterior inferior cerebellar artery (PICA) is an infrequent developmental anomaly predisposing an individual to intracranial aneurysm formation. Fenestration of the PICA is extremely rare, and furthermore, fenestration of the double origin of the PICA in association with an intracranial aneurysm is unique. We present the first reported case of fenestration of the double origin of the PICA associated with a dissecting aneurysm of the contralateral vertebral artery (VA) that healed spontaneously after medical observation.