Iatrogenic dissection on atherosclerotic stenosis of the middle cerebral artery caused by stent retriever thrombectomy for internal carotid artery embolic occlusion.

Background: Arterial dissection is a rare complication of mechanical thrombectomy, and the risk factors and clinical course are not well known. We report a case of iatrogenic dissection on atherosclerotic stenosis of the middle cerebral artery (MCA) caused by stent retriever thrombectomy for internal carotid artery (ICA) embolic occlusion. Case Description: A 78-year-old woman underwent mechanical thrombectomy for ICA embolic occlusion. Preprocedural angiography indicated a thrombus from the C1 segment of the left ICA to the proximal M1 segment of the left MCA and slow antegrade contrast opacification of the mid- to distal-M1. A stent retriever was deployed across the stenotic lesion and pulled back to retrieve a thrombus. Although reperfusion was achieved, mid-M1 occlusion occurred the next day. We considered that endothelial damage from the stent retriever caused iatrogenic dissection at existing atherosclerotic stenosis at mid-M1. Conclusion: Stent retriever thrombectomy can worsen atherosclerotic stenosis. Vascular imaging follow-up is important after thrombectomy in patients with intracranial stenotic lesions. Clinicians should be aware that iatrogenic dissections can be more likely in atherosclerotic vessels following stent retriever thrombectomy.