Intracranial aneurysms associated with a double origin of the posterior inferior cerebellar artery.

The posterior inferior cerebellar artery (PICA) frequently has a variable course and target territory. However, double origin PICA is a rare finding. Its significance is uncertain, but it has been associated with intracranial aneurysms localized at the PICA proper or at a distant site. The presence of this variation imposes specific challenges. We describe two cases of double origin PICA, one of them associated with an ipsilateral PICA aneurysm. The role of this finding was critically reviewed. A literature search identified 23 cases of double origin PICA, including both cases reported in this paper. Intracranial aneurysms were strongly associated with double origin PICA (71% in 21 detailed cases of double origin PICA). The current patient harboring a PICA aneurysm was successfully treated by endovascular trapping. In the setting of double origin PICA aneurysms, this variation beneficially affects the treatment choice once the two limbs enable the safe sacrifice of the channel involved, with preservation of blood flow through the other channel.