[Four cases of fusiform posterior inferior cerebellar artery aneurysms successfully treated by trapping and occipital artery-PICA bypass].

Aneurysms located on the proximal portion of the posterior inferior cerebellar artery (PICA) are rare, and even rarer are fusiform aneurysms in this location. Therefore the principles of surgical management are poorly understood and still subject to debate. The management plan for these lesions is based on the proper understanding of the PICA anatomy, and particularly the origin of important perforating arteries. As many anatomic variations of PICA can be observed and the perforator's origin is sometimes in complex anatomical relations with the aneurysm, the management has to be individualized in each case. The objective of management is to exclude of the aneurysm from the circulation while preserving the perforator and distal flow. We report four cases of PICA fusiform aneurysms of the anterior or lateral medullary segments which were treated successfully with trapping of the abnormal arterial segment and distal revascularization of PICA. Trapping was adjusted to the specific anatomical circumstances in each case, preserving perforators to the maximum and revascularizing (OA-distal PICA) distal territory.