Effects Of Carotid Artery Stenting On Cognitive Function,Cerebral Perfusion And Neural Network In Patients With Asymptomatic Carotid Artery Stenosis

Background Carotid artery stenosis without transient ischemic attack(TIA)or stroke is considered as "asymptomatic".However,recent studies have demonstrated that these"asymptomatic" carotid artery stenosis(aCAS)patients had cognitive impairment in executive function,memory and psychomotor speed.However,the pathophysiological changes underlying these impairments largely remain unknown.Although carotid artery stenting(CAS)have been proven can reduce future strokes,the effect of carotid artery stenting on cognition are conflicting.In recent years,pulsed arterial spin labeling(pASL)MRI,Proton MR Spectroscopy(MRS)and Resting-state functional MRI(R-fMRI)have been employed to study cognition impairment This study aimed to evaluate the cognitive impairment in severe aCAS patients and the impact of carotid artery stenting by utilizing an integrated MRI including pASL MRI,MRS and R-fMRI.Methods In part one,19 asymptomatic,severe(?70%)and unilateral internal carotid artery(ICA)stenosis patients were compared with 24 healthy controls on 5 neuropsychiatric tests(including the MMSE,the MoCA Beijing Version,the Digit Symbol Test,the Rey Auditory Verbal Learning Test and the Verbal Memory Test)and an integrated MRI(including pASL MRI,MRS and R-fMRI).In part two,we prospectively enrolled 16 asymptomatic,severe(?70%),unilateral internal carotid artery stenosis patients,who are going to perform carotid artery stenting.Cognition assessment and integrated MRI were administered 7 days before and 3 months after carotid artery stenting.Results aCAS patients showed significantly lower scores in all cognitive tests.Utilizing this integrated MRI,we also found aCAS patients suffered from decreased cerebral blood flow in the Left Frontal Lobe,had lower NAA/Cr ratio in the left hippocampus and decreased connectivity to the posterior cingulate cortex(PCC)in the anterior part of default mode network(DMN).After carotid artery stenting,significant improvement in the scores on the MMSE,the Verbal Memory test and the delayed recall were found.After stenting,patients showed increased perfusion in the Left Frontal Gyrus,increased amplitude of low-frequency fluctuation(ALFF)in the Right Precentral Gyrus and increased connectivity to the PCC in the Right Supra Frontal Gyrus.However,no significant correlation was found between these imaging changes and cognition scores.Conclusion Hypoperfusion in the Left Frontal Lobe,lower NAA/Cr ratio in the left hippocampus and decreased connectivity to the PCC in the anterior part of DMN might be partly responsible for the cognition impairment in aCAS patients.Successful carotid artery stenting can partly improve cognition in aCAS patients.This improvement may be partly attributed to the increased perfusion in the Left Frontal Gyrus,increased ALFF in the Right Precentral Gyrus and increased connectivity to the PCC in the Right Supra Frontal Gyrus.