Microembolic Signals In The Symptomatic And Asymptomatic Patients With Intracranial And Extracranial Artery Stenosis

Background and purpose: Microembolus monitoring by TCD iswidely used for ischemic cerebrovascular disease, especially inexploring the mechanisms of ischemic stroke with intracranial andextracranial artery stenosis, in evaluating the treatment efficacyas well as evaluating the prognosis, but there is few researchesabout the clinical significance of MES in asymptomatic intracranialand extracranial artery stenosis. In our study, we studied andcompared MES incidence and related factors in symptomatic andasymptomatic intracranial and extracranial artery stenosis as wellas acute ischemic stroke patients without intracranial andextracranial artery stenosis, also we studied whether MES couldpredict the ischemic stroke in asymptomatic intracranial andextracranial artery stenosis.Method: We choosed consecutive patients of the First BethuneHospital of Jilin University who diagnosed symptomatic andasymptomatic intracranial and extracranial artery stenosis as well as acute ischemic stroke patients without intracranial andextracranial artery stenosis, but we exclude the patiens who havetandem stenosis in the intracranial and extracranial artery, alsothe patients who have potential cardiogenic emboli and blood borneemboli as well as any other artery borne embolic source were notincluded in our study. All the patients underwent microembolicsignal monitoring by TCD.Results: In the group of symptomatic artery stenosis, Weidentified227patients (including73symptomatic internal carotidstenosis,126symptomatic middle cerebral artery stenosis and28symptomatic vertebral-basilar artery stenosis). In the group ofacute ischemic stroke patients without intracranial andextracranial artery stenosis, there were43patients meet thecriterion, and in the asymptomatic artery stenosis, we identified109patients with140arteries stenosis (including26asymptomaticinternal carotid artery stenosis and83asymptomatic middlecerebral artery stenosis). By comparing the symptomatic arterystenosis group and the acute ischemic stroke patients withoutintracranial and extracranial artery stenosis group, we found thatthe smoking history and the MES positive rate of the two groups is different (P <0.01), while the other risk factors were not (P>0.05).Further we compared the MES-positive and MES-negative group of thesymptomatic artery stenosis, we did not find any difference of riskfactors between the two groups (P>0.05).In the symptomatic artery stenosis group, the MES rate ofinternal carotid artery stenosis, middle cerebral artery stenosisand vertebral-basilar artery stenosis is25/73(34.25%),49/126(38.89%) and11/28(39.29%), and there is no difference of MESrate (P>0.05). We divided the arteries of symptomatic arterystenosis group into light stenosis group, middle stenosis group,severe stenosis and near occlusive group, by comaring the MES ratewe found that: the MES rate of light stenosis group is differentfrom middle stenosis group (P=0.02) and severe stenosis group (P=0.004), but there is no difference between light stenosis groupand near occlusive group, MES rate of middle stenosis group isdifferent from near occlusive group (P=0.0005), but there is nodifference between middle stenosis group and severe stenosis group,also the MES rate is different from severe stenosis group and nearocclusive group (P=0.000).By comparing the symptomatic (73patients) and asymptomatic (26 patients) internal carotid artery stenosis group, there is nodifference of the risk factors between the two groups (P>0.05),and the rate of middle and severe artery stenosis of the two groupdid not differ. But the MES rate of the symptomatic and asymptomaticinternal carotid artery stenosis group is25/73(34.25%) and3/32（9.38%），the symptomatic group is higher than asymptomatic group(P <0.01).By comparing the symptomatic (126patients) and asymptomatic(83patients) middle cerebral artery stenosis group, we found theratio of male and smoking history are different (P <0.01), and thereare no difference of other risk factors, and the MES rate of thesymptomatic and asymptomatic middle cerebral artery stenosis groupis49/126(38.89%) and2/108(1.85%)，the symptomatic group is higherthan the asymptomatic group (P <0.01).By comparing the asymptomatic internal carotid artery stenosisand asymptomatic middle cerebral artery stenosis group, there aredifference of age and the ratio of male (P <0.01), but there areno difference of other risk factors, the MES rate of the asymptomaticinternal carotid artery stenosis and middle cerebral arterystenosis group is2/108(1.85%) and3/32(9.38%), and there is no difference of the MES rate (P>0.05).In the asymptomatic internal carotid artery stenosis andasymptomatic middle cerebral artery stenosis group,5patients werefound MES, and the number of MES is1,1,3,1,1, and during the followup (6month to1year), nobody develop ischemic stroke.Conclusion:1. MES is correlated with artery stenosis, and themore severe stenosis of the artery is, the higher the MES rate is,but the near occlusive artery have a low MES rate.2. MES iscorrelated with symptom of ischemic stroke, which suggested thatartery-to-artery embolism may be one of the mechanism of ischemicstroke.3. The atherosclerotic plaque of the asymptomatic arterystenosis especially the asymptomatic middle cerebral arterystenosis is stable.4. MES in the asymptomatic artery stenosis isnot a predictor of subsequent ischemic stroke, but the result needsfurther research.