The mid-term effects of carotid endarterectomy on cognition and regional neural activity analyzed with the amplitude of low frequency fluctuations technique

Abstract

Purpose The study aims to evaluate the mid-term effects of carotid endarterectomy (CEA) on cognition and resting-state functional magnetic resonance imaging (rs-fMRI) using the Amplitude of Low Frequency Fluctuations (ALFF) technique. Methods In this observational study, patients eligible for CEA were prospectively included. On the same day, within 1 week of the CEA procedure performed and 12 months after the CEA procedure, all patients underwent (i) an MRI examination for rs-fMRI analysis and (ii) a cognitive evaluation using the Italian version of the Mini-Mental State Examination (MMSE) corrected for age and schooling. Pre-CEA and post-CEA MMSE scores were evaluated using paired sample t-tests, adopting a p-value < 0.05 as statistical threshold. The ALFF technique was used for analyzing the differences between pre-CEA and post-CEA rs-fMRI scans in terms of regional neural activation. This was accomplished by applying non-parametric statistics based on randomization/permutation for cluster-level inferences, adopting a cluster-mass p-value corrected for false discovery < 0.05 for cluster threshold, and a p-uncorrected < 0.01 for the voxel threshold. Results Twenty asymptomatic patients were enrolled. The mean MMSE score resulted improved following CEA procedure (p-value = 0.001). The ALFF analysis identified a single cluster of 6260 voxels of increased regional neural activity following CEA, and no cluster of reduced activity. The majority of voxels covered the right precentral gyrus, the right middle frontal gyrus, and the anterior division of the cingulate gyrus. Conclusion Mid-term cognitive improvements observed after CEA are associated to increased regional neural activity of several cerebral regions.

Functional MRI evaluation of cognitive effects of carotid stenosis revascularization

“…Data showed that the earliest fMRI investigation of cognitive effects of the carotid stenosis revascularization was published in 2012 (Cheng et al., 2012 ). Most studies were conducted using high‐field MRI (3 Tesla), except two that were conducted at 1.5T (Porcu et al., 2019 ; Porcu et al., 2021 ). Only one study applied a cognitive task (Chinda et al., 2021 ), whereas the rest were resting‐state studies (Cheng et al., 2012 ; Huang et al., 2018 ; Lin et al., 2016 ; Porcu et al., 2019 ; Porcu et al., 2021 ; Tani et al., 2018 ; Wang et al., 2017 ).…”

“…Most studies were conducted using high‐field MRI (3 Tesla), except two that were conducted at 1.5T (Porcu et al., 2019 ; Porcu et al., 2021 ). Only one study applied a cognitive task (Chinda et al., 2021 ), whereas the rest were resting‐state studies (Cheng et al., 2012 ; Huang et al., 2018 ; Lin et al., 2016 ; Porcu et al., 2019 ; Porcu et al., 2021 ; Tani et al., 2018 ; Wang et al., 2017 ). Clinical revascularization interventions included CAS alone (Cheng et al., 2012 ; Chinda et al., 2021 ; Huang et al., 2018 ; Tani et al., 2018 ; Wang et al., 2017 ), CEA alone (Porcu et al., 2019 ), and combined CAS and medical therapy (Lin et al., 2016 ).…”

“…The mean age of patients across the studies was 71.2 ± 7.7 years (median = 71.4), whereas the sex ratio of the research patients was male predominated, ranging from 70 to 100% (mean = 82.0 ± 12.5 %, median = 79.5%). Most of the studies were done on asymptomatic patients (Cheng et al., 2012 ; Huang et al., 2018 ; Lin et al., 2016 ; Porcu et al., 2019 ; Porcu et al., 2021 ; Wang et al., 2017 ); one study investigated only symptomatic patients (Lin et al., 2016 ); one study investigated both symptomatic and asymptomatic patients (Chinda et al., 2021 ). Only a couple of the studies (Cheng et al., 2012 ; Lin et al., 2016 ) carried out analyses of imaging findings and cognitive assessments blinded to diagnosis and treatment (Table 1A ).…”

“…Most of the resting‐phase studies examined the default mode network components; although several studies also examined brain regions including the dorsal attention, somatosensory, and salience networks (Table 1B ). The Mini Mental State Exam (MMSE) total score, which tests global cognition, was popular among studies where neuropsychological testing was applied (Cheng et al., 2012 ; Huang et al., 2018 ; Lin et al., 2016 ; Porcu et al., 2019 ; Porcu et al., 2021 ; Wang et al., 2017 ); although other tests, such as the Stroop test that measures a range of cognitive domains, were also used by some studies (Table 1B ).…”

“…Most recently, Porcu et al. ( 2021 ) studied asymptomatic unilateral carotid stenosis patients by contrasting the resting‐phase fMRI data 1 week pre‐CEA and 12 months post‐CEA. They observed treatment‐related increases in regional neural activity in the right precentral gyrus, middle frontal gyrus, and the anterior division of the cingulate gyrus; while the MMSE scores saw statistically significant improvements at the 12 months’ evaluation (Tables 1A and 1B ).…”