Abstract
ObjectiveSevere carotid artery stenosis (CAS) can lead to atrophy of gray matter (GM) and memory impairment; however, the underlying mechanism is unknown. Thus, we aimed to identify memory impairment and GM atrophy and explore the possible correlation between them in patients with asymptomatic severe CAS.MethodsTwenty-four patients with asymptomatic severe CAS and 10 healthy controls completed the mini-mental state examination (MMSE) and clinical memory scale (CMS) and underwent 7T magnetic resonance imaging (MRI) scan. Field intensity inhomogeneities were corrected. Images were processed using VBM8, and GM images were flipped. First, 11 flipped and 10 non-flipped images of patients with unilateral CAS and 5 flipped and 5 non-flipped images of controls were pre-processed using DARTEL algorithm and analyzed using an analysis of variance (ANOVA). Second, flipped and non-flipped images of unilateral patients were similarly pre-processed and analyzed using the paired t-test. Third, pre-processed non-flipped GM images and CMS scores of 24 patients were analyzed by multiple regression analysis. Nuisance variables were corrected accordingly.ResultsBasic information was well matched between patients and controls. MMSE scores of patients were in the normal range; however, memory function was significantly reduced (all P < 0.05). GM volumes of patients were significantly reduced in the anterior circulation regions. The stenosis-side hemispheres showed greater atrophy. GM volumes of the left pars opercularis, pars triangularis, and middle frontal gyrus were strongly positively correlated with the total scores of CMS (all r > 0.7, P = 0.001). Additionally, the left middle frontal gyrus was strongly positively correlated with associative memory (r = 0.853, P = 0.001). The left pars opercularis was moderately positively correlated with semantic memory (r = 0.695, P = 0.001).ConclusionPatients with asymptomatic CAS suffer from memory impairment. Bilateral anterior circulation regions showed extensive atrophy. The hemisphere with stenosis showed severer atrophy. Memory impairment in patients may be related to atrophy of the left frontal gyrus and atrophy of different regions may result in different memory impairments.
Highlights
Carotid artery stenosis (CAS), a type of vascular degenerative disease, can cause cerebral ischemic events, such as amaurosis, transient ischemic attack (TIA), and stroke, which threaten life and health
Baseline information, including age, gender, details of stenosis, and education background, is listed in Table 1, and there were no statistical differences between patients with asymptomatic severe CAS and healthy controls
General Memory Function We found that the gray matter (GM) volumes of the left frontal pars triangularis, left frontal pars opercularis, and the frontal part of the left middle frontal gyrus were strongly positively correlated with the total score of clinical memory scale (CMS)
Summary
Carotid artery stenosis (CAS), a type of vascular degenerative disease, can cause cerebral ischemic events, such as amaurosis, transient ischemic attack (TIA), and stroke, which threaten life and health. Thinning of the cortex is considered a potential biomarker, which has shown to be associated with cognitive impairment in aging, neurodegenerative disease, and small vascular disease (Seo et al, 2010; Kim et al, 2014; Pettigrew et al, 2016; Weston et al, 2016). All these studies raise the possibility that cortical thinning in CAS patients may contribute to memory decline; this has not been clarified. Locating the specific correlating cortex may allow a better understanding of the mechanism of memory impairment in CAS patients
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