Silent Brain Infarction In Patients With Asymptomatic Internal Carotid Artery Occlusion

Objective : To analyze the clinical characteristics of silent cerebral infarction(SBI)in patients with asymptomatic internal carotid artery occlusion(AICAO)and its correlation with the outcome of cerebrovascular diseases.Materials & methods : A total of 95 patients with AICAO were recruited from Neurology Department of The first Affiliated Hospital of Soochow University between January 2012 and October 2016.The clinical characteristics of these 95 patients were analyzed retrospectively.The size,distribution and hemodynamic characteristics of SBI were compared by nonparametric test.Possible influencing factors of SBI in AICAO patients were analyzed by logistic regression,then the independent risks and the developed regression model was evaluated by ROC curve of its diagnostic value for SBI.The effect of SBI on AICAO patients' cerebrovascular outcome was analyzed by survival analysis and ROC curve.Results : AICAO,with commonly occult pathogenesis,is mainly caused by systematic atherosclerosis progression(74.74%,d71/95)gradually.Occlusion most frequently occured at common carotid artery bifurcation and the beginning of ICA(C1 segment,71.57%,68/95),secondly at ophthalmic or communicating segment of ICA(C6/7 segment,25.26%,24/95).Brain MRI scan suggested SBI lesions in the anterior circulation of AICAO patients were of high incidence(66.3%),more prone to the occluded side[52.94%vs34.12%(contralateral side),P=0.012].The vast majority lesions(91/119)were lacunar infarction located in the deep brain parenchyma,diameter 3 ~ 15 mm,but the proportion of lesions over 15 mm diameter significantly increased regarding of cortical site.Coronary disease was the most impressively independent risk factor of predicting SBI in AICAO patients(OR:21.386,95%CI:3.080-148.489),followed by carotid artery unstable plaque(OR:13.331,95%CI:1.1971-108.408),contralateral ICA stenosis(OR:1.732,95%CI: 1.122-2.673).Above three-risk joint assessment has a moderate value for predicting SBI(AUC:0.880,95%CI:0.570-0.818).Luckily,current "medical treatment",at least including anti-platelet/anticoagulation,enhanced lipid regulation and control of blood pressure,stable blood glucose levels,improved bad habits,was effective to prevent SBI(OR:0.089,95%CI:0.019-0.420).By using Kaplan-Meier survival analysis,the cumulative survival rate of no SBI group was significantly higher than that of SBI group(90.9 %vs 65.4%,P = 0.048).However,there wasn't sufficient supportive evidence(AUC:0.636,95%CI: 0.493-0.783,P=0.100)for judging AICAO patients' poor cerebrovascular prognosis by SBI alone yet.Conclusions:1.Most of AICAO is chronic athresia caused by atherosclerosis,ICA C1 segment is the most frequently involved.2.there was a high incidence of ipsilateral SBI lesions in the anterior circulation of AICAO patients and a characteristic distribution according to lesion size,which meant that embolism,hypoperfusion,cerebral microvascular disease were all involved in SBI pathogenesis of AICAO patients.3.Coronary heart disease,contralateral ICA stenosis,carotid artery instability plaque were independent risk factors to SBI in AICAO with "medical treatment" bringing effective prevention from it.4.Combined assessment of AICAO patients with coronary disease history,contralateral ICA stenosis,carotid plaque character had a moderate diagnostic value for SBI.Although strongly associated with cerebrovascular outcomes in AICAO patients,SBI can't independently predicate poor cerebrovascular prognosis yet.