Plaque Ulceration and Lumen Thrombus Are the Main Sources of Cerebral Microemboli in High-grade Internal Carotid Artery Stenosis

Abstract

Background and Purpose Previous work has shown that rates of cerebral microemboli downstream of high-grade internal carotid artery stenosis are higher in recently symptomatic compared with asymptomatic patients. In addition, microembolic rates decline after carotid endarterectomy. We conducted a prospective investigation of 40 consecutive asymptomatic or recently symptomatic patients undergoing carotid endarterectomy for 70% to 95% internal carotid artery stenosis to determine the relationship between microembolic rate and pathoanatomic features of the carotid plaque. Methods Transcranial Doppler monitoring including automated emboli detection was performed preoperatively to assess the rate of cerebral microemboli of the ipsilateral middle cerebral artery. The corresponding endarterectomy specimens were evaluated histologically with respect to the occurrence of plaque fissuring, intraplaque hemorrhage, plaque ulceration, or intraluminal thrombosis. Results There were strong associations between plaque ulceration, intraluminal thrombosis, and downstream cerebral microemboli ( P ≤.005, respectively). There were no correlations of microembolism with plaque fissuring or intraplaque hemorrhage ( P =.82 and P =.28, respectively). Conclusions We conclude that ulceration and luminal thrombosis of the atheromatous plaque are the main sources of downstream cerebral microemboli in patients with high-grade internal carotid artery stenosis. Our data support the view that these pathoanatomic features may also play a key role in symptom development.