Effect of carotid artery stenting on cognitive function in patients with asymptomatic carotid artery stenosis, a multimodal magnetic resonance study

Introduction: More and more evidence suggesting that internal carotid artery stenosis is not only a risk factor for ischemic stroke but also for cognitive impairments. Hypoperfusion and silent micro emboli have been reported as the pathophysiological mechanisms causing cognitive impairment. The effect of carotid artery stenting (CAS) on cognitive function varied from study to study. This study aims to explore the effect of CAS on cognition and exam the changes in cerebral perfusion and brain connectivity with pulsed arterial spin labeling (pASL) and resting-state functional MRI (R-fMRI).

Methods: We conducted a controlled trial to assess alterations in cognitive performance among patients with "asymptomatic" carotid artery stenosis prior to and 3 months post-CAS intervention. Cognitive function including the Montreal Cognitive Assessment (MoCA) Beijing Version, the Minimum Mental State Examination (MMSE), the Digit Symbol Test, the Rey Auditory Verbal Learning Test (RAVLT), and the Verbal Memory Test. pASL perfusion MRI and R-fMRI were also performed prior to and 3 months post-CAS intervention.

Results: 13 patients completed all the follow-up. We observed increased perfusion in the right parietal lobe and right occipital lobe, increased amplitude of low-frequency fluctuation (ALFF) in the right precentral gyrus, increased connectivity to the posterior cingulate cortex (PCC) in the right frontal gyrus and right precuneus, and increased voxel-wise mirrored homotopic connectivity (VMHC) in the right precuneus 3 months after CAS when compared with prior to CAS. Cognitive test results showed significant improvement in the scores on the MMSE, the Verbal Memory test, and the delayed recall.

Conclusion: CAS can partly improve the cognitive function in patients with "asymptomatic" carotid artery stenosis, and the improvement may be attributable to the increased perfusion in the right parietal lobe and right occipital lobe, increased ALFF in the right precentral gyrus, increased connectivity to the PCC in the right frontal gyrus and right precuneus, and increased VMHC in the right precuneus.