Cognitive Deficits in Symptomatic and Asymptomatic Carotid Endarterectomy Surgical Candidates

Cognition and Cerebral Blood Flow After Extracranial Carotid Revascularization for Carotid Atherosclerosis: A Systematic Review

PURPOSE

Extracranial atherosclerotic carotid stenosis is associated with inadequate cerebral blood flow (CBF) and cognitive dysfunction. The impact of extracranial carotid revascularization on cognition and how any cognitive change relates to changes in CBF are less clear. This review examines the effects of revascularization of extracranial carotid disease by carotid endarterectomy (CEA) or carotid stenting (CAS) on cognition, and how this relates to changes in CBF.

METHODS

A systematic review of existing reports in the Medline, Embase, and Cochrane databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement recommendations. All original retrospective or prospective studies and clinical trials that compared pre- and postoperative cognitive function and CBF in patients with extracranial carotid stenosis who underwent CEA or CAS versus a control group, published between January 1985 and December 2022, were identified and considered eligible for inclusion in this study.

FINDINGS

Seven studies (661 participants; 460 CEA or CAS) were identified. All were observational studies and of moderate to good methodologic quality. Six studies (619 participants; follow-up range 1 month to 2 years) demonstrated improvement in some cognitive domains following CEA or CAS, improvement in CBF following revascularization, and correlated some of these cognitive changes with changes in CBF. One study (42 participants; 3 months follow-up) found cognitive improvement following CEA, but found no improvement in CBF or any correlation between cognitive and CBF change. The literature however represented heterogenous study populations examining asymptomatic and/or symptomatic carotid stenosis, differing in treatment modality and criteria for control groups ranging from healthy volunteers to those with stenosis but not who underwent surgical revascularization, and finally, differing reporting methods. This heterogeneity precluded meta-analysis.

IMPLICATIONS

Definitive conclusions are limited by variation in cognitive function assessment, timing of testing, and how these are correlated to CBF. However, research suggests a potential improvement in cognition which may be associated with improvement in CBF, particularly in those patients who have more significant CBF deficit at baseline. Further studies are required to better understand this association and provide a clearer picture of the cognitive effects of carotid revascularization.

Cognitive impairment in asymptomatic cerebral arterial stenosis: a P300 study

BACKGROUND

Cerebral arterial stenosis (CAS), in the absence of a structural lesion, can result in cognitive impairment that represents an ongoing contention among studies. Accordingly, we investigated cognitive functions in asymptomatic patients with CAS, using P300 which is a neurophysiological tool. We also compared cognition in intracranial stenosis (ICS) and extracranial stenosis (ECS).

METHODS

Asymptomatic patients with CAS (≥ 70%) in the absence of structural brain lesions were categorized into ICS and ECS groups of 15 patients each, in addition to 15 normal controls. MRI, MRA, CT angiography, P300 analysis, Mini-Mental State examination (MMSE), Wisconsin Card Sorting Test (WCST), and Wechsler Memory Scale Test-Revised (WMST) were performed to all patients.

RESULTS

Impairment on all cognitive scales ranged from 70 up to 100% among CAS group. Prolonged p300 latency and reaction time correlated with worse performance on WMST (p = 0.02), while lower amplitude and decreased accuracy correlated with more errors on WCST (p = 0.01). ICS scores on WCTS were lower than those of ECS group (p = 0.001), while ECS had a longer reaction time (p = 0.02) and lower scores on MMS and WMST than those of ICS group (p = 0.03).

CONCLUSION

Patients with asymptomatic CAS had a high prevalence of cognitive dysfunction which places them at risk of higher morbidity. ICS group showed impairment on executive functions, while the ECS group showed predilection to memory and information processing dysfunction.

Clinical Values and Underlying Mechanism Analysis of Serum miR-455-5p in Carotid Artery Stenosis

Purpose

Carotid artery stenosis (CAS) is a leading cause of cerebral infarction, its early diagnosis and intervention are necessary. In light of the important role of microRNAs (miRNAs) in cerebrovascular disease, this study aimed to investigate the expression pattern and clinical significance of serum miR-455-5p in the onset and development of CAS, as well as its underlying mechanism.

Patients and Methods

Seventy patients with asymptomatic CAS were recruited, and the development of cerebral ischemia events (CIEs) was recorded during the five-years follow-up. qRT-PCR was performed for the serum miR-455-5p detection. ROC curve was applied for the diagnostic ability evaluation. By constructing multivariable logistic or cox regression model, odds ratio (OR) or hazard ratio (HR) were calculated to assess the impact of each risk factor on independent variables. Human aortic endothelial cells (HAECs) were treated with ox-LDL to induce endothelial cell damage. The role of miR-455-5p in the cell viability, apoptosis, oxidative stress and inflammatory response was detected.

Results

Serum miR-455-5p showed low expression in cases with CAS, and had an independent influence on the degree of CAS. The diagnostic ability of serum miR-455-5p to diagnose CAS was determined via ROC curve, with the AUC of 0.927. During follow-up, patients with low miR-455-5p expression showed high incidence of CIEs. In multivariable cox regression model, degree of CAS and miR-455-5p were significant risk factors for the development of CIEs in the CAS patients. In vitro, miR-455-5p was at a low expression in HAECs cell models and can prevent cells from ox-LDL induced cell apoptosis, oxidative stress and inflammatory response. SOCS3 was a target gene of miR-455-5p and upregulated in ox-LDL treated cells.

Conclusion

Down-regulated expression of serum miR-455-5p is hopeful to be used as a biomarker for the early diagnosis of CAS. MiR-455-5p is an independent risk factor for the degree of CAS, and has a certain predictive value for the development of CIEs. That might be associated with the protective role of miR-455-5p against ox-LDL-induced endothelial cell injury via targeting SOCS3.

Carotid Plaque Strain Indices Were Correlated With Cognitive Performance in a Cohort With Advanced Atherosclerosis, and Traditional Doppler Measures Showed no Association

OBJECTIVES

Traditional Doppler measures have been used to predict cognitive performance in patients with carotid atherosclerosis. Novel measures, such as carotid plaque strain indices (CPSIs), have shown associations with cognitive performance. We hypothesized that lower mean middle cerebral artery (MCA) velocities, higher bulb-internal carotid artery (ICA) velocities, the MCA pulsatility index (PI), and CPSIs would be associated with poorer cognitive performance in individuals with advanced atherosclerosis.

METHODS

Neurocognitive testing, carotid ultrasound imaging, transcranial Doppler imaging, and carotid strain imaging were performed on 40 patients scheduled for carotid endarterectomy. Kendall tau correlations were used to examine relationships between cognitive tests and the surgical-side maximum peak systolic velocity (PSV; from the bulb, proximal, mid, or distal ICA), mean MCA velocity and PI, and maximum CPSIs (axial, lateral, and shear strain indices used to characterize plaque deformations with arterial pulsation). Cognitive measures included age-adjusted indices of verbal fluency, verbal and visual learning/memory, psychomotor speed, auditory attention/working memory, visuospatial construction, and mental flexibility.

RESULTS

Participants had a median age of 71.0 (interquartile range, 9.75) years; 26 were male (65%), and 14 were female (35%). Traditional Doppler parameters, PSV, mean MCA velocity, and MCA PI did not predict cognitive performance (all P > .05). Maximum CPSIs were significantly associated with cognitive performance (P < .05).

CONCLUSIONS

Traditional velocity measurements of the maximum bulb-ICA PSV, mean MCA velocity, and PI were not associated with cognitive performance in patients with advanced atherosclerotic disease; however, maximum CPSIs were associated with cognitive performance. These findings suggest that cognition may be associated with unstable plaque rather than blood flow.

Effect of Unilateral Carotid Artery Stenting on Cognitive Function in Patients with Severe Bilateral Stenosis

CASE DESCRIPTION

An 82-year-old man with dementia, gait disturbance, and a small cerebral infarction owing to severe bilateral carotid artery stenosis was successfully treated with carotid artery stenting (CAS). Preoperative cerebral vascular reactivity was reduced in the bilateral cerebral hemispheres. We performed CAS to treat right internal carotid artery stenosis. Following CAS, cerebral vascular reactivity showed an increase in the bilateral cerebral hemispheres. Memory, fluency, and attention also showed improvement.

CONCLUSIONS

This case illustrates the potential benefit of single-stage CAS for cognitive function in severe bilateral carotid artery stenosis without hyperperfusion syndrome.

Lagrangian carotid strain imaging indices normalized to blood pressure for vulnerable plaque

OBJECTIVE

Ultrasound Lagrangian carotid strain imaging (LCSI) utilizes physiological deformation caused by arterial pressure variations to generate strain tensor maps of the vessel walls and plaques. LCSI has been criticized for the lack of normalization of magnitude-based strain indices to physiological stimuli, namely blood pressure. We evaluated the impact of normalization of magnitude-based strain indices to blood pressure measured immediately after the acquisition of radiofrequency (RF) data loops for LCSI.

MATERIALS AND METHODS

A complete clinical ultrasound examination along with RF data loops for LCSI was performed on 50 patients (30 males and 20 females) who presented with >60% carotid stenosis and were scheduled for carotid endarterectomy. Cognition was assessed using the 60-minute neuropsychological test protocol.

RESULTS

For axial strains correlation of maximum accumulated strain indices (MASI), cognition scores were -0.46 for non-normalized and -0.45, -0.49, -0.37, and -0.48 for systolic, diastolic, pulse pressure, and mean arterial pressure normalized data, respectively. The corresponding area under the curve (AUC) values for classifiers designed using maximum likelihood estimation of a binormal distribution with a median-split of the executive function cognition scores were 0.73, 0.70, 0.71, 0.70, and 0.71, respectively.

CONCLUSIONS

No significant differences in the AUC estimates were obtained between normalized and non-normalized magnitude-based strain indices.

The Preservation of Cognition 1 Year After Carotid Endarterectomy in Patients With Prior Cognitive Decline

BACKGROUND

Vascular cognitive decline is critically important in the course of atherosclerosis and stroke.

OBJECTIVE

To explore the hypothesis that carotid endarterectomy (CEA) by removing an unstable plaque may slow the course of vascular cognitive decline in both symptomatic and asymptomatic patients.

METHODS

Patients with clinically significant (>60%) carotid stenosis were studied preop and 1 yr post-CEA for clinical symptoms, vascular cognitive decline, instability of carotid plaque-presence of microemboli, brain white matter changes, and medical risk factors.

RESULTS

Forty-six percent were classically symptomatic. All patients showed vascular cognitive decline at presentation which correlated with degree of plaque instability. Significant white matter hyperintensity changes (48.7%) and cerebral emboli (25%) were also seen at baseline in both classically symptomatic and asymptomatic. One year after CEA, both groups showed no decline in cognitive function and significant improvement in 2 tests (P = .028 and P = .013). Brain white matter hyperintensities were unchanged. Microemboli were reduced but remained present (17.86%). Improvement was predicted by the presence of hypertension (P = .001), or less advanced cognitive decline preoperatively (P = .009).

CONCLUSION

This study demonstrates the importance of vascular cognitive decline in atherosclerotic disease. This is a function of the degree of instability of the atherosclerotic plaque more than the presence of stroke symptoms. It further suggests that atherosclerotic vascular cognitive decline need not be inevitable, and may be modified by treating hypertension and removal of the unstable plaque. This highlights the need for continued research on the cognitive effects of cerebrovascular disease and the synergistic benefits of intensive medical and surgical therapy.

Cortical thickness and cognitive performance in asymptomatic unilateral carotid artery stenosis

Background

We investigated changes of cortical thickness and its association with cognitive performance in patients with high-grade carotid artery stenosis without ischemic brain lesions.

Methods

We studied 25 patients with unilateral carotid artery stenosis ≥50% and 25 age-matched controls. All subjects underwent T1-weighted MRI, and cortical thickness was measured in 33 regions of interest in each hemisphere, as well as in brain regions belonging to the vascular territory of the middle cerebral artery (MCA). General linear mixed models were fitted to the dependent variable cortical thickness. Cognitive assessment comprised the Stroop Test and Trail Making Test B.

Results

In the linear mixed model, presence of carotid stenosis had no effect on cortical thickness. There was a significant interaction of stenosis and region with a trend towards lower cortical thickness in the MCA region on the side of carotid stenosis. Patients with carotid stenosis performed significantly worse on the Stroop test than controls, but there was no correlation with cortical thickness.

Conclusion

In patients with carotid stenosis without ischemic brain lesions, neither a clear pattern of reduced cortical thickness nor an association of cortical thickness with cognitive function was observed. Our data do not support the hypothesized association of cortical thinning and cognitive impairment in carotid stenosis.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1127-y) contains supplementary material, which is available to authorized users.

A Cross-Sectional Investigation of Cognition and Ultrasound-Based Vascular Strain Indices

OBJECTIVE

We examine the relationship between variability in the plaque strain distribution estimated using ultrasound with multiple cognitive domains including executive, language, visuospatial reasoning, and memory function.

METHOD

Asymptomatic (n = 42) and symptomatic (n = 34) patients with significant (>60%) carotid artery stenosis were studied for plaque instability using ultrasound strain imaging and multiple cognitive domains including executive, language, visuospatial reasoning, and memory function. Correlation and ROC analyses were performed between ultrasound strain indices and cognitive function. Strain indices and cognition scores were also compared between symptomatic and asymptomatic patients to determine whether there are significant group differences.

RESULTS

Association of high-strain distributions with dysexecutive function was observed in both asymptomatic and symptomatic patients. For memory, visuospatial, and language functions, the correlations between strain and cognition were weaker for the asymptomatic compared to symptomatic group.

CONCLUSIONS

Both asymptomatic and symptomatic patients demonstrate a relationship between vessel strain indices and executive function indicating that silent strokes and micro-emboli could initially contribute to a decline in executive function, whereas strokes and transient ischemic attacks may cause the further decline in other cognitive functions.

Influence of Severe Carotid Stenosis on Cognition, Depressive Symptoms and Quality of Life

BACKGROUND

Carotid artery disease is not just a causal risk factor of ischemic stroke, but may predispose patients to depressive symptoms and low health related quality of life (HRQoL).

OBJECTIVES

The objectives of the present study were to assess the association between severe carotid artery stenosis (CAS) and cognitive impairment, frequency of depressive symptoms and status of HRQoL.

METHODS

Cross - sectional study involved 55 patients with severe CAS and 54 patients with lower extremity peripheral artery disease (PAD). Cognitive impairment was assessed using Montreal Cognitive Assessment Scale (MoCA), depressive symptoms - PHQ-9 scale. HRQoL was measured using Medical Outcome Survey Short Form version 2 (SF-36v2).

RESULTS

Median MoCA score 24 [23;26] was significantly lower in patients with severe CAS than in patients with PAD - 26 [25-28],(p=0.005; effect size r=0.3). There was no statistically significant difference of median PHQ-9 scores the in CAS group (median PHQ-9 score 4.0 [5]) and in the PAD group (median PHQ-9 score 5.5 [7]), (p=0.08, effect size r=0.18). Mean SF-36v2 scores were similar in CAS and PAD groups except for bodily pain (p=0.001, Cohen's d value = 0.77) and vitality (p=0.02, Cohen's d value = 0.49).

CONCLUSION

In summary, our findings indicate that severe CAS could play a role in cognitive decline. Further studies should be conducted using larger patient cohorts without ischemic brain lesions and with balanced vascular risk profiles to investigate impact of CAS on cognition. There was no association between severe CAS and depressive symptoms in the present study. As patients with severe CAS did not exhibit physical symptoms, HRQoL was better for those patients than for patients with lower extremity PAD.

Transcranial Doppler and Microemboli Detection: Relationships to Symptomatic Status and Histopathology Findings

The purpose of this study was to determine the relationship between symptomatic status, transcranial Doppler (TCD) microemboli presence and plaque histopathology findings. TCD was performed on 60 patients (37 symptomatic, 23 asymptomatic) before undergoing clinically indicated carotid endarterectomy. The frequency of microemboli signals was not significantly different between symptomatic and asymptomatic subject groups (p = 0.88) and there were no differences observed in the macroscopic or histopathology scoring of these plaques (p-values all > 0.05). The presence of microemboli was associated with an ulceration score (regardless of symptomatic or asymptomatic status, p = 0.034), with a one-level increase in ulceration rating associated with an odds ratio of 5.86 (95% [CI] 1.55, 43.4). These findings suggest that both symptomatic and asymptomatic patients may have plaque with similar features of instability and ability to create emboli. Thus, identifying new ways to measure plaque instability may provide important information for optimizing treatment to prevent future stroke.

Visual Aids for Improving Patient Decision Making in Severe Symptomatic Carotid Stenosis

BACKGROUND

Because of the large amount of information to process and the limited time of a clinical consult, choosing between carotid endarterectomy (CEA) and carotid angioplasty with stenting (CAS) can be confusing for patients with severe symptomatic internal carotid stenosis (ICA).

GOAL

We aim to develop a visual aid tool to help clinicians and patients in the decision-making process of selecting between CEA and CAS.

MATERIALS AND METHODS

Based on pooled analysis from randomized controlled trials including patients with symptomatic and severe ICA (SSICA), we generated visual plots comparing CEA with CAS for 3 prespecified postprocedural time points: (1) any stroke or death at 4 months, and (2) any stroke or death in the first 30 days and ipsilateral stroke thereafter at 5 years and (3) at 10 years.

RESULTS

A total of 4574 participants (2393 assigned to CAS, and 2361 to CEA) were included in the analyses. For every 100 patients with SSICA, 6 would develop any stroke or death in the CEA group compared with 9 undergoing CAS at 4 months (hazard ratio [HR] 1.53; 95%CI 1.20-1.95). At 5 years, 7 patients in the CEA group would develop any periprocedural stroke or death and ipsilateral stroke thereafter versus 12 undergoing CAS (HR 1.72; 95%CI 1.24-2.39), compared with 10 patients in the CEA and 13 in the CAS groups at 10 years (HR 1.17; 95%CI 0.82-1.66).

CONCLUSION

Visual aids presented in this study could potentially help patients with severe symptomatic internal carotid stenosis to better weigh the risks and benefits of CEA versus CAS as a function of time, allowing for the prioritization of personal preferences, and should be prospectively assessed.

Quantification of carotid artery plaque stability with multiple region of interest based ultrasound strain indices and relationship with cognition

Vulnerability and instability in carotid artery plaque has been assessed based on strain variations using noninvasive ultrasound imaging. We previously demonstrated that carotid plaques with higher strain indices in a region of interest (ROI) correlated to patients with lower cognition, probably due to cerebrovascular emboli arising from these unstable plaques. This work attempts to characterize the strain distribution throughout the entire plaque region instead of being restricted to a single localized ROI. Multiple ROIs are selected within the entire plaque region, based on thresholds determined by the maximum and average strains in the entire plaque, enabling generation of additional relevant strain indices. Ultrasound strain imaging of carotid plaques, was performed on 60 human patients using an 18L6 transducer coupled to a Siemens Acuson S2000 system to acquire radiofrequency data over several cardiac cycles. Patients also underwent a battery of neuropsychological tests under a protocol based on National Institute of Neurological Disorders and Stroke and Canadian Stroke Network guidelines. Correlation of strain indices with composite cognitive index of executive function revealed a negative association relating high strain to poor cognition. Patients grouped into high and low cognition groups were then classified using these additional strain indices. One of our newer indices, namely the average L  -  1 norm with plaque (AL1NWP) presented with significantly improved correlation with executive function when compared to our previously reported maximum accumulated strain indices. An optimal combination of three of the new indices generated classifiers of patient cognition with an area under the curve (AUC) of 0.880, 0.921 and 0.905 for all (n  =  60), symptomatic (n  =  33) and asymptomatic patients (n  =  27) whereas classifiers using maximum accumulated strain indices alone provided AUC values of 0.817, 0.815 and 0.813 respectively.

Carotid atherosclerotic plaque instability and cognition determined by ultrasound-measured plaque strain in asymptomatic patients with significant stenosis

OBJECTIVE This article describes the use of ultrasound measurements of physical strain within carotid atherosclerotic plaques as a measure of instability and the potential for vascular cognitive decline, microemboli, and white matter changes. METHODS Asymptomatic patients with significant (> 60%) carotid artery stenosis were studied for dynamic measures of plaque instability, presence of microemboli, white matter changes, and vascular cognitive decline in comparison with normative controls and premorbid state. RESULTS Although classically asymptomatic, these patients showed vascular cognitive decline. The degree of strain instability measured within the atherosclerotic plaque directly predicted vascular cognitive decline in these patients thought previously to be asymptomatic according to classic criteria. Furthermore, 26% of patients showed microemboli, and patients had twice as much white matter hyperintensity as controls. CONCLUSIONS These data show that physical measures of plaque instability are possible through interpretation of ultrasound strain data during pulsation, which may be more clinically relevant than solely measuring degree of stenosis. The data also highlight the importance of understanding that the definition of symptoms should not be limited to motor, speech, and vision function but underscore the role of vascular cognitive decline in the pathophysiology of carotid atherosclerotic disease. Clinical trial registration no.: NCT02476396 (clinicaltrials.gov).