Background and purpose: We investigated whether cerebral microembolism as detected by transcranial Doppler ultrasonography (TCD) identifies patients at an increased risk for early, recurrent cerebral or retinal ischemic events.
Methods: Records of consecutive patients examined during a 40-month period in the Neurovascular Laboratory were reviewed for the presence of cerebral microembolism. Of the original 302 patients, 229 with 310 arteries met inclusionary criteria. Follow-up information was obtained from the laboratory's database as well as the hospital records. Microembolus detection studies were performed on TC-2000 or TC-2020 instruments equipped with special software, and criteria established a priori were used for microembolus selection. TCD testing was performed a median interval of 9 days after the initial symptoms of cerebral ischemia. Severity of arterial stenosis was determined by cerebral angiography or noninvasive methods.
Results: Microembolic signals were detected more frequently in symptomatic (40/140; 28.6%) than asymptomatic (21/170; 12.4%) arteries (P < .001). Ten recurrent ischemic events occurred during a median follow-up of 8 days after TCD examination, all in the territories of symptomatic arteries. Nine events occurred in the territories of microembolic signal positive arteries (9/61; 14.8%) and one in the territory of a microembolic signal-negative artery (1/249; 0.4%) (P < .00). No association was detected in the subgroup with known cardiac lesions. Microembolic signals were more frequent in arteries with lesions causing 70% or more stenosis or occlusion (26/99; 26.3%) than in those with a degree of stenosis less than 70% (17/126; 13.5%) (P = .016).
Conclusions: In this retrospective study, microembolic signals were more common in the territories of symptomatic arteries and particularly those with severely stenotic lesions. During a short follow-up, recurrent ischemic events were more common along the territories of arteries with TCD-detected microembolism and previous symptoms of cerebral or retinal ischemia.