Tailored PICA Revascularization for Unusual Ruptured Fusiform Vertebro-PICA Origin Aneurysms: Rationale and Case Illustrations

Ruptured fusiform aneurysms of the vertebral artery involving posterior inferior cerebellar artery (PICA) origin are difficult to manage without sacrificing PICA. In this report, two very unusual cases are described which highlight different revascularization strategies that may be required. The first case initially appeared to be a small saccular PICA origin aneurysm, but detailed angiography showed a serpentine recanalization of a fusiform aneurysm. This was treated with PICA-PICA anastomosis and trapping of the aneurysm. The second case is a dissecting vertebral aneurysm with both PICA and the anterior spinal artery originating from the dome. PICA was found to be a bihemispheric variant, so no in situ bypass was available, and an occipital artery to PICA bypass was performed. The vertebral artery was occluded proximally only and follow-up angiography showed remodeling of the distal vertebral artery with the anterior spinal artery filling by retrograde flow from the distal vertebral artery. These cases illustrate both the anatomic variability of this region as well as the need to be familiar with multiple treatment strategies including revascularization techniques to be able to successfully treat these aneurysms.