Right occipital to Right distal PICA bypass and trapping of ruptured Right PICA dissecting aneurysm after initial coil embolization.

Posterior inferior cerebellar artery (PICA) aneurysms are rare, constituting less than 5 % of intracranial aneurysms, and are associated with a high rupture risk [1]. Management is challenging due to proximity to brainstem structures, the need for vessel reconstruction or excision, and the risk of ischemia in PICA territory [2,3]. We present a case of subarachnoid hemorrhage caused by a ruptured, dissecting ∼1 cm proximal PICA aneurysm. The aneurysm had a calcified neck, and the contralateral PICA was small and not adjacent to the ipsilateral PICA. Treatment was staged: first, partial endovascular coil embolization to prevent re-rupture during ICU care [4,5], followed by an occipital-to-PICA artery (p3) bypass via a far lateral approach. The bypass enabled successful aneurysm trapping and resection. This case demonstrates the importance of staged endovascular and surgical interventions in managing large, complex aneurysms and highlights technical aspects of posterior circulation bypass.