Delayed Rebleeding from Pseudoaneurysm After Mechanical Thrombectomy Using Stent Retriever Due to Small Artery Avulsion Confirmed by Open Surgery

Abstract

Pseudoaneurysm after mechanical thrombectomy (MT) is rare but is one of the potential complications associated with endovascular procedures. There is limited information regarding its mechanism of formation and the potential risk of delayed bleeding. An 84-year-old woman was admitted to our institution with right hemiplegia and global aphasia. Magnetic resonance imaging and angiography revealed occlusion of the M2 segment of the left middle cerebral artery with subtle acute ischemic change in this territory. After initiating intravenous thrombolysis, MT was performed for persistent occlusion of the M2. Successful revascularization was finally achieved with a single pass of a Trevo XP 3 mm× 20 mm stent retriever; significant deviation of the vessel occurred during withdrawal of the stent retriever. Anticoagulation was initiated after confirming resolution of a small amount of postprocedural subarachnoid hemorrhage 1 day after the procedure. However, 4 days after the procedure, computed tomography and angiography revealed a massive sylvian hematoma with de novo formation of a small pseudoaneurysm at the site where the stent retriever was deployed. Open surgery revealed a small artery avulsion at this site. The lesion was closed by microsurgical suturing. Angiographic and intraoperative findings showed that the mechanism of formation of the pseudoaneurysm was small artery avulsion resulting from deviation of the vessel during withdrawal of the stent retriever. When performing MT in a tortuous distal vessel, the possibility of small artery avulsion should be kept in mind to both prevent and manage critical hemorrhagic complications.