Vessel Wall Injury After Stent Retriever Thrombectomy for Internal Carotid Artery Occlusion with Duplicated Middle Cerebral Artery

Background: Experimental evidence that stent retriever thrombectomy (SRT) may cause arterial wall damage is increasing, although histopathologic findings focused on vessel wall injury after SRT have not fully been reported in humans. Case Description: We describe an autopsy case of an 82-year-old woman who presented with acute left intracranial internal carotid artery occlusion and received SRT. When we attempted to catheterize the M1 segment of the normal middle cerebral artery (MCA), we were not aware of a duplicated MCA and advanced the microcatheter into the main MCA trunk with a smaller caliber than that of the normal M1 segment. A 6-mm Trevo thrombectomy device was deployed from the main MCA trunk but was insufficiently expanded in the MCA segment. Two passes with a Trevo resulted in failed recanalization. The patient died on postoperative day 4 because of extensive infarction. Autopsy revealed a duplicated MCA and subintimal arterial dissection in the proximal segment of the main MCA trunk. The supraclinoid internal carotid artery also revealed endothelial denudation and mural thrombus. Conclusions: We provide a histopathologic report of vessel wall injury after SRT that caused failed recanalization. Anatomic variations of the MCA should be considered when selecting suitable thrombectomy devices in order to avoid vessel wall injury.