Abstract: ObjectiveTo determine the frequency of cerebral microembolism in patients with asymptomatic or symptomatic extracranial and intracranial arterial stenosis and to assess its relationship to the onset and course of ischemic stroke.MethodsTCD was used to monitor patients with extracranial and intracranial cerebral arterial stenosis. Double channel four-gated and power M-Mode were used to detect microembolic signals (MES). The recording time was 60 min and the number of MES was counted. Patients were divided into 2 groups as extracranial internal carotid artery (ICA) stenosis and middle cerebral artery (MCA) stenosis. Each group was divided into 3 subgroups as asymptomatic, acute ischemic stroke (<30 d) and old ischemic stroke (≥30 d).ResultsThe total number of monitored artery was 74 in 63 patients. In ICA stenosis with asymptom, old ischemic stroke and acute ischemic stroke, the frequency of MES was 0(0/10), 0(0/7), 33%(6/18) and the number of MES in acute ischemic stroke was 3, 9, 8, 10, 1, 40 (mean=11.8). In MCA stenosis with asymptom, old ischemic stroke and acute ischemic stroke, the frequency of MES was 14%(2/14), 14%(1/7), 39%(7/18) and the number of MES was 4 and 1 in asymptom, 1 in old ischemic stroke, 4, 1, 4, 15, 16, 1 and 29(mean=10) in acute ischemic stroke. In ICA stenosis, the difference between acute ischemic stroke and asymptom (P=0.013), between acute and old ischemic stroke (P=0.031) reached statistic significance.In MCA stenosis, there was no significant difference between acute ischemic stroke and asymptom (P=0.115), so as between acute and old ischemic stroke (P=0.214).ConclusionEmbolism was important in the mechanism of ischemic stroke due to extracranial and intracranial arterial stenosis. The closer to ischemic stroke onset, the higher the frequency and the number of MES. TCD monitor was helpful to study the pathogenesis of ischemic stroke due to extracranial and intracranial arterial stenosis and determine the treatment.

Key words: cerebral artery, stenosis, cerebral embolism, ultrasonics