Delayed Rupture from a Pseudoaneurysm after Mechanical Thrombectomy: A Case Report.

Pseudoaneurysm following mechanical thrombectomy (MT) is a rare but possible complication associated with endovascular procedures. This report presents a case of delayed rupture of a pseudoaneurysm after MT with a stent retriever, which was confirmed by open surgery. During hospitalization, an 85-year-old woman had right hemiplegia and aphasia. Magnetic resonance imaging and angiography revealed acute ischemic changes in the left middle cerebral artery because of M2 segment occlusion. MT was performed to address persistent M2 occlusion. Retrieving from distal vessels with the fully deployed Solitaire 4 × 20 mm stent retriever was considered dangerous, we resheathed the stent, but the microcatheter jumped distally. Angiography through microcatheter revealed contrast leakage into the subarachnoid space. The diagnosis was vessel perforation caused by the microcatheter. The lesion was treated with temporary balloon occlusion for 5 minutes using a balloon-guiding catheter, combined with the reversal of heparin anticoagulation by protamine, and a systolic blood pressure reduction to below 120 mm Hg. Anticoagulation was initiated after confirming that postprocedural subarachnoid hemorrhage (SAH) decreased 1 day after the procedure. Fourteen days after the procedure, computed tomography and angiography revealed a massive hematoma with a newly formed small pseudoaneurysm at the site of vessel rupture. Open surgery was performed to close the small artery rupture using a clip. Delayed rupture of the pseudoaneurysm occurred after MT using a stent retriever. If SAH is observed after MT, performing follow-up computed tomography angiography or magnetic resonance angiography is recommended to consider pseudoaneurysm formation.