Study On The Correlation Between Cerebral Hemodynamics And Severity Of White Matter Lesions And Cortical Microinfarcts In Patients With Ischemic Stroke

PartⅠ Correlation between cerebral hemodynamics and severity of white matter lesions in patients with ischemic stroke Background:The pathogenesis underlying age-related white matter changes(ARWMC)remains unclear.Recent evidence suggests a possible correlation between intracranial atherosclerotic stenosis(ICAS)and ARWMC,which needs further verification.In addition,it is uncertain how ICAS would influence the severity of ARWMC.Objectives:This study was to investigate the relationship between cerebral hemodynamics and the severity of white matter in patients with ischemic stroke and the influencing factors of white matter lesions in patients with ischemic stroke.Methods:Patients with a recent ischemic stroke or transient ischemic attack and a middle cerebral artery(MCA)-M1 stenosis(50-99%)on magnetic resonance angiography(MRA),within the Chinese Intracranial Atherosclerosis(CICAS)cohort,were screened and recruited to the current study.The distal to proximal signal intensity ratio(SIR)of a MCA stenosis was measured on MRA to represent its hemodynamic significance.The relationships between the degree of MCA stenosis,SIR and the severity of ipsilateral ARWMC assessed on T2-weighted fluid attenuated inversion recovery images were analyzed.For a patient with bilateral MCA-M1 stenosis,the side with a higher degree of stenosis was chosen for such analyses.Results:Overall,180 subjects(mean age,63.7±11.6 years)were recruited.ARWMC scales were significantly,linearly and negatively correlated with SIR of ipsilateral MCA stenosis(Spearman correlation coefficient,-0.543;p<0.001).but not the degree of stenosis(p=0.93).Multivariate ordinal logistic regression revealed that age(OR=1.037;95% CI,1.008-1.066;p=0.011)and SIR(OR=0.010;95%CI,0.002-0.058;p<0.001)were significantly associated with the severity of ipsilateral ARWMC.Conclusions:The effects of ICAS on the severity of ipsilateral ARWMC may lie in its hemodynamic significance and the consequent hypoperfusion,rather than the degree of stenosis.Further studies are needed to validate such findings and unlock the underlying pathophysiological mechanisms.Part II Correlation between cerebral hemodynamics and cortical infarcts in patients with ischemic stroke Background:Cortical microinfarct(CMI)has been reported of potential clinical relevance.It was previously considered only visible upon microscope,but was recently reported visible on 3.0 Tesla MRI and linked to presence of intracranial stenosis.We investigated incidence of CMIs and associated factors in stroke patients with atherosclerotic middle cerebral artery(MCA)stenosis.Objectives:This study was designed to investigate the incidence of CMIs in patients with acute ischemic stroke accompanied by atherosclerotic MCA stenosis and its influencing factors.Methods:Patients with a recent non-cardioembolic ischemic stroke or transient ischemic attack in the Chinese Intracranial Atherosclerosis(CICAS)cohort were screened and those with a MCA-M1 stenosis(50-99%)were recruited in the current study.The severity of MCA stenosis was defined as moderate(50-69%)or severe(70-99%)on time-of-flight MR angiography(MRA).The distal to proximal signal intensity ratio(SIR)of MCA stenosis was measured on time-of-flight MRA to represent its hemodynamic significance.The presence of CMI(s)in ipsilateral hemisphere to an index MCA stenosis was assessed on axial T1/T2-weighted images and T2-weighted fluid-attenuated inversion-recovery(FLAIR)images.Relationships between the stenotic severity,SIR,and other factors with the presence of ipsilateral CMI(s)were analyzed.Results:Overall,86 patients(mean age 62.8 years;77.9% males)were analyzed.Sixty-six(76.7%)and 20(23.3%)patients respectively had moderate and severe MCA-M1 stenoses,with a median SIR of 0.91.Forty-five(52.3%)patients had CMI(s),with 28(32.6%)having 1 CMI and 17(19.8%)having multiple CMI(s).Age(p=0.033),a history of dyslipidemia(p=0.016),intervals from onset to admission(p=0.024)and to MRI exam(p=0.012),and percentages of patients with a SIR <median(p=0.033)were significantly different between patients with and without CMI(s)in univariate analyses.Multivariate logistic regression showed that a history of dyslipidemia(OR=6.83,95% CI 1.67-27.94;p=0.008)and a SIR lower than median(OR=4.73,95% CI 1.37-16.26;p=0.014)were independently associated with presence of CMI(s)in ipsilateral hemisphere to a MCA-M1 stenosis.Conclusions:Patients with stroke and intracranial stenosis had a high burden of CMI.Except for a history of dyslipidemia,the hemodynamic significance of the arterial stenosis and the downstream hypoperfusion may contribute to the presence of CMI(s)in these patients,which warrants further investigation in prospective,longitudinal studies.