Flow Alteration Therapy for Ruptured Vertebral Artery Dissecting Aneurysms Involving the Posterior Inferior Cerebellar Artery.

Surgery for- and endovascular treatment of vertebral artery (VA) dissecting aneurysms involving the origin of the posterior inferior cerebellar artery (PICA) remain challenging. Their ideal treatment is complete isolation of the aneurysm by surgical or endovascular trapping plus PICA reconstruction. However, postoperative lower cranial nerve palsy and medullary infarction are potential complications. We report four patients with VA dissecting aneurysms involving the PICA origin who were treated by occipital artery (OA)-PICA bypass followed by proximal occlusion of the VA and clip ligation of the PICA origin instead of trapping. There were no procedural or ischemic complications. In all patients, angiography performed 2-3 weeks later showed good patency of the bypass graft and complete obliteration of the aneurysm. During the follow-up period ranging from 1 to 14 years, none experienced bleeding. Although retrograde blood flow to the dissecting aneurysm persisted in the absence of trapping, iatrogenic lower cranial nerve injury could be avoided. The decrease in aneurysmal flow might elicit spontaneous thrombosis and prevent aneurysmal rerupture. Our technique might be less invasive than aneurysmal trapping and help to prevent rebleeding.