Extracranial aneurysm of the distal PICA presenting as isolated fourth ventricular hemorrhage: case report and literature review.

BACKGROUND: Posterior inferior cerebellar artery (PICA) aneurysms are relatively uncommon, comprising only 0.5-3% of all intracranial aneurysms. Distal PICA aneurysms are much more uncommon, with more than 200 cases being reported in the literature. The finding of an extracranially located aneurysm of distal PICA is considered a true rarity. METHODS AND DISCUSSION: A rare case of extracranially located PICA aneurysm presenting with isolated fourth ventricular hemorrhage is presented and the diagnostic and therapeutic challenges discussed.