A case of cerebral cardioembolism successfully treated by Merci retriever despite a large ischemic change on diffusion-weighted MR imaging

A 63-year-old man with paroxysmal atrial fibrillation presented with aphasia (16:30) followed by right hemiplegia. The last known time that he was clinically well was 14:30. On admission (17:43), his baseline NIHSS score was 34. Head diffusion-weighted MR imaging (DWI) demonstrated large hyperintense signals throughout the left middle cerebral artery (MCA) territory. The left carotid angiogram (CAG) demonstrated occlusion of the left ICA 2 cm distal from the bifurcation. The right CAG showed a small branch laterally extending from the left anterior cerebral artery (ACA). Mechanical thrombectomy with a Merci retriever removed a large amount of thrombi after the first trial. The left ICA and MCA were recanalized to grade TICI 2b. The left hemiplegia was markedly improved, and he could walk independently. His NIHSS score was 11 at discharge. Revascularization therapy may improve a motor deficit in patients with possible penumbra of the precentral gyrus by collateral circulation from the ACA even if the ischemic lesion in the MCA territory is large on DWI.