Asymptomatic carotid stenosis is associated with mobility and cognitive dysfunction and heightens falls in older adults

Impact of carotid stenosis on the outcome of stroke patients submitted to reperfusion treatments: a narrative review

Intravenous thrombolysis (IT) and mechanical thrombectomy (MD) are the two interventional approaches that have changed the outcome of patients with acute ischemic stroke (AIS). Ipsilateral and contralateral carotid stenosis (ICS, CCS) play an important role in regulating cerebral hemodynamics, both in chronic and acute situations such as AIS. Several studies have explored their role in the incidence and severity of stroke, but very few have investigated the possible impact of ICS and CCS on the efficacy of interventional procedures. The purpose of this review was to I) highlight the incidence and prevalence of carotid stenosis (CS); II) assess the impact of ICS and CCS on cerebral hemodynamics; III) evaluate the effect of carotid stenosis on the efficacy of interventional therapies (IT and MT) for AIS; and IV) report therapeutic complications related to CS. We searched PubMed/Medline for case reports, reviews, and original research articles on English-language review topics during the period from January 1, 2000 to October 1, 2023. CS is associated with 15-20 % of the total number of AIS. ICS and CCS had a negative influence on both cerebral hemodynamics before AIS and outcome after interventional procedures (IT, MT alone or in bridging). Available data on cerebral hemodynamics and efficacy of interventional therapies for AIS suggest a negative role of CS. Therefore, early diagnosis of CS may be considered relevant to preventive and post-stroke treatment strategies.

An international, multispecialty, expert-based Delphi Consensus document on controversial issues in the management of patients with asymptomatic and symptomatic carotid stenosis

OBJECTIVE

Despite the publication of various national/international guidelines, several questions concerning the management of patients with asymptomatic (AsxCS) and symptomatic (SxCS) carotid stenosis remain unanswered. The aim of this international, multi-specialty, expert-based Delphi Consensus document was to address these issues to help clinicians make decisions when guidelines are unclear.

METHODS

Fourteen controversial topics were identified. A three-round Delphi Consensus process was performed including 61 experts. The aim of Round 1 was to investigate the differing views and opinions regarding these unresolved topics. In Round 2, clarifications were asked from each participant. In Round 3, the questionnaire was resent to all participants for their final vote. Consensus was reached when ≥75% of experts agreed on a specific response.

RESULTS

Most experts agreed that: (1) the current periprocedural/in-hospital stroke/death thresholds for performing a carotid intervention should be lowered from 6% to 4% in patients with SxCS and from 3% to 2% in patients with AsxCS; (2) the time threshold for a patient being considered "recently symptomatic" should be reduced from the current definition of "6 months" to 3 months or less; (3) 80% to 99% AsxCS carries a higher risk of stroke compared with 60% to 79% AsxCS; (4) factors beyond the grade of stenosis and symptoms should be added to the indications for revascularization in AsxCS patients (eg, plaque features of vulnerability and silent infarctions on brain computed tomography scans); and (5) shunting should be used selectively, rather than always or never. Consensus could not be reached on the remaining topics due to conflicting, inadequate, or controversial evidence.

CONCLUSIONS

The present international, multi-specialty expert-based Delphi Consensus document attempted to provide responses to several unanswered/unresolved issues. However, consensus could not be achieved on some topics, highlighting areas requiring future research.

Association between high-sensitivity cardiac troponin I and fall-related hospitalisation in women aged over 70 years

OBJECTIVE

To examine the association between high-sensitivity cardiac troponin I (hs-cTnI), a biomarker of myocardial injury, muscle function decline and 14.5-year fall-related hospitalisation risk in women aged over 70 years.

METHODS

1179 ambulatory community-dwelling women aged over 70 years with subclinical levels of hs-cTnI (ie, <15.6 ng/L), who were followed up for 14.5 years, were included. Samples for hs-cTnI were obtained in 1998. Fall-related hospitalisations were retrieved from linked health records. Muscle function measures, including handgrip strength and the Timed-Up-and-Go (TUG) test, were assessed in 1998 and 2003.

RESULTS

Mean±SD age was 75.2±2.7 years. Over 14.5 years of follow-up, 40.4% (476 of 1179) experienced fall-related hospitalisation. Participants were categorised into four approximate hs-cTnI quartiles: quartile 1 (<3.6 ng/L), quartile 2 (3.6-4.4 ng/L), quartile 3 (4.5-5.8 ng/L) and quartile 4 (≥5.9 ng/L). Compared with those in Q1, women in Q4 were likely to experience fall-related hospitalisation (36.0% vs 42.8%). In a multivariable-adjusted model that accounted for CVD and fall risk factors, compared with women in Q1, those in Q4 had a 46% higher risk of fall-related hospitalisation (HR 1.46, 95% CI 1.08 to 1.98). Additionally, women in Q4 had slower TUG performance compared with those in Q1 (10.3 s vs 9.5 s, p=0.032).

CONCLUSION

Elevated level of hs-cTnI was associated with slower TUG performance and increased fall-related hospitalisation risk. This indicates subclinical level of hs-cTnI can identify clinically relevant falls, emphasising the need to consider cardiac health during fall assessment in women aged over 70 years.

TRIAL REGISTRATION NUMBER

ACTRN12617000640303.

Sonographic assessment of carotid intima-media thickness in healthy young Thai adults

Purpose

Early detection of carotid stenosis can reduce cardiovascular risk. In this study, the maximum-carotid intimamedia thickness (CIMT), the mean-CIMT, and the presence of plaque were examined in healthy young Thai adults. Additionally, correlations between CIMT and cardiovascular risk factors were assessed.

Materials and Methods

Left and right carotid arteries of 302 participants (15-45 years old) were scanned, with CIMT measured at the far walls of the common carotid artery, carotid bulb, and internal carotid artery. Demographics and risk factors were assessed using a questionnaire. Ten random participants were re-scanned after 4 weeks.

Results

The study included 123 (40.70%) male and 179 (59.30%) female participants. The max-CIMT, mean-CIMT, and plaque thickness were 0.400±0.100, 0.403±0.095 and 1.520±0.814 mm, respectively. Male participants had significantly higher CIMT values for nearly all locations and age groups. The right-sided CIMT values were higher for all locations. The carotid bulb had the greatest CIMT values (0.437±0.178 mm), followed by the common (0.403±0.095 mm) and internal (0.361±0.099 mm) carotid arteries. Plaque was present in 18 locations (1.00%), affecting 15 participants (4.97%). These plaques were found in the right carotid bulb (n=9; 0.50%), left carotid bulb (n=7; 0.39%), and right internal carotid artery (n=2; 0.11%). Adjusted multivariable regression revealed significant positive associations between CIMT and male, increased age and "other" occupation (P<0.05).

Conclusion

Both max-CIMT and mean-CIMT were approximately 0.4 mm. Plaque was observed in 4.97% of patients, with an average thickness of 1.5 mm. The most influential risk factors for increased CIMT were sex, age, and occupation.

Symptomatic Common Carotid Artery Stenosis Managed With Carotid Endarterectomy

Extracranial carotid artery disease is typical at the carotid bifurcation and internal carotid artery (ICA) and is rarely symptomatic from isolated common carotid artery (CCA) stenosis. We present the case of a 60-year-old female patient who presented with a transient ischemic attack (TIA) with significant stenosis of the ipsilateral CCA only, without any involvement of the ICA or bifurcation. This was treated with carotid endarterectomy (CEA) with desirable postoperative outcomes; at up to six months postoperative follow-up, this patient had no recurrence of symptoms. We draw attention to the current gap in the literature with regard to a lack of specific guidelines for optimal evidence-based surgical treatment for this specific condition, with recent advances within certain vascular societies.

Effects of asymptomatic cerebral artery stenosis of anterior circulation and establishment of collateral circulation on cognition

OBJECTIVE

The purpose of this study is to investigate how cognition is affected by asymptomatic cerebral artery stenosis (CAS) of the anterior circulation and its related collateral circulation.

METHODS

102 patients with CAS of the anterior circulation and 52 controls were enrolled from January 1, 2019 to June 30, 2022. Patients with CAS of anterior circulation were further divided into different subgroups according to the degree of stenosis, cerebral perfusion, and collateral circulation. A series of neuropsychological scales were used to evaluate the participant's cognitive function, activities of daily living, and neuropsychiatric symptoms (such as memory, execution, psychomotor speed, etc.). The data were analyzed using T-test, F-test, chi-square test, rank sum test, and other statistical methods, moreover, the quantitative data were further examined for trends. The relationship between the degree of CAS, cerebral perfusion, collateral circulation, and the outcome of the cognitive test was investigated using Spearman correlation analysis.

RESULTS

Compared to controls, there were severe impairments of global cognition, psychomotor speed/execution, memory, attention, activities of daily living, and more neuropsychiatric symptoms in patients with anterior circulation CAS (p < 0.05), and these impairments got worsened with the aggravation of CAS (p < 0.05). The global cognition, psychomotor speed / executive function, memory function, and daily living ability were impaired both in the cerebral perfusion-compensated group and decompensated group(p < 0.05), while there was no statistically significant difference between the two groups (p > 0.05). With the aggravation of CAS, the proportion of poor collateral formation increased, and this difference was statistically significant (P < 0.01). The degree of stenosis, cerebral perfusion, and collateral circulation establishment of anterior circulation CAS was correlated with global cognition, memory, psychomotor speed, execution, attention, activities of daily living, and neuropsychiatric symptoms (all p < 0.01).

CONCLUSION

Cognitive impairment and the percentage of inadequate collateral circulation development rise as stenosis progresses in patients with anterior circulation CAS. The decline in global cognitive function was accompanied by impairments in psychomotor speed / executive function, memory function, attention, and daily living skills, as well as the aggravation of neuropsychiatric symptoms, especially in patients with impaired cerebral perfusion and poor collateral circulation formation.

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.

Study of cognitive function in patients with severe asymptomatic carotid artery stenosis by a computerized neuropsychological assessment device

Background

Carotid stenosis can lead to stroke and cognitive impairment. Moreover, the cognitive function was assessed mostly by paper and pencil cognitive tests. This study aimed to evaluate the impact of severe asymptomatic carotid artery stenosis (SACAS) on cognitive function by a computerized neuropsychological assessment device (CNAD). The diagnostic value of screening SACAS of the CNAD was analyzed.

Methods

There were 48 patients with ≥70% asymptomatic carotid stenosis and 52 controls without carotid stenosis. Duplex ultrasound defined the degree of stenosis. The differences of cognitive function were analyzed between patients and controls. The relationship of scores of cognitive tests and age were analyzed in the linear regression equation. The diagnostic value of CNAD was evaluated by the receiver operating characteristic (ROC) curve.

Results

Stenosis and control subjects had no statistically significant differences in baseline characteristics. Stenosis patients had worse scores for Stroop color-word test (p = 0.002), one back test (p = 0.013), and identification test (p = 0.006) corresponding to attention and executive ability. The analysis of linear regression equation indicated that cognitive scores of stenosis patients declined faster with age, especially for digit span test, Stroop color-word test, one back test and identification test. In analysis of ROC curve, the Stroop color-word test (p = 0.002), one back test (p = 0.013), and identification test (p = 0.006), and comprehensive index of the three tests (p = 0.001) had the diagnostic value.

Conclusion

The CNAD has evaluation value and screening value for patients with cognitive impairment and SACAS. But it is necessary to update the CNAD and conduct a study with a bigger sample.

Measures of carotid atherosclerosis and fall-related hospitalization risk: The Perth Longitudinal Study of Ageing Women

BACKGROUND AND AIMS

We and others have identified links between cardiovascular conditions and poor musculoskeletal health. However, the relationship between measures of carotid atherosclerosis such as focal carotid plaque and common carotid intima media thickness (CCA-IMT) and falls remains understudied. This study examined the association between measures of carotid atherosclerosis and fall-related hospitalization over 11.5 years in community dwelling older women.

METHODS AND RESULTS

1116 older women recruited in 1998 to a five-year randomized controlled trial to examine the effect of calcium supplementation in preventing fracture and who had undertaken B-mode ultrasound in 2001 (three years after the baseline clinical visit) were included in this study. The participants were followed for over 11.5 years as Perth Longitudinal Study of Ageing Women (PLSAW). Over the follow up period, 428 (38.4%) women experienced a fall-related hospitalization. Older women with carotid plaque had 44% a higher relative hazard for fall-related hospitalization (HR 1.44; 95%CI, 1.18 to 1.76) compared to those without carotid plaque. The association persisted after adjustment for established falls risk factors such as measures of muscle strength and physical function.Each SD increase in the mean and maximum CCA-IMT was also associated with a higher risk of fall-related hospitalizations (HR 1.10; 95%CI, 1.00 to 1.21 and HR 1.11; 95%CI, 1.01 to 1.22, respectively).

CONCLUSIONS

Measures of carotid atherosclerosis are associated with a higher risk of fall-related hospitalization independent of established falls risk factors. These findings suggest the importance of vascular health when considering falls risk.

eICAB: A novel deep learning pipeline for Circle of Willis multiclass segmentation and analysis

BACKGROUND

The accurate segmentation, labeling and quantification of cerebral blood vessels on MR imaging is important for basic and clinical research, yet results are not generalizable, and often require user intervention. New methods are needed to automate this process.

PURPOSE

To automatically segment, label and quantify Circle of Willis (CW) arteries on Magnetic Resonance Angiography images using deep convolutional neural networks.

MATERIALS AND METHODS

MRA images were pooled from three public and private databases. A total of 116 subjects (mean age 56 years ± 21 [standard deviation]; 72 women) were used to make up the training set (N=101) and the testing set (N=15). In each image, fourteen arterial segments making up or surrounding the CW were manually annotated and validated by a clinical expert. Convolutional neural network (CNN) models were trained on a training set to be finally combined in an ensemble to develop eICAB. Model performances were evaluated using (1) quantitative analysis (dice score on test set) and (2) qualitative analysis (external datasets, N=121). The reliability was assessed using multiple MRAs of healthy participants (ICC of vessel diameters and volumes on test-retest).

RESULTS

Qualitative analysis showed that eICAB correctly predicted the large, medium and small arteries in 99±0.4%, 97±1% and 88±7% of all images, respectively. For quantitative assessment, the average dice score coefficients for the large (ICAs, BA), medium (ACAs, MCAs, PCAs-P2), and small (AComm, PComm, PCAs-P1) vessels were 0.76±0.07, 0.76±0.08 and 0.41±0.27, respectively. These results were similar and, in some cases, statistically better (p<0.05) than inter-expert annotation variability and robust to image SNR. Finally, test-retest analysis showed that the model yielded high diameter and volume reliability (ICC=0.99).

CONCLUSION

We have developed a quick and reliable open-source CNN-based method capable of accurately segmenting and labeling the CW in MRA images. This method is largely independent of image quality. In the future, we foresee this approach as a critical step towards fully automated analysis of MRA databases in basic and clinical research.

Associations between carotid atherosclerotic plaque characteristics determined by magnetic resonance imaging and improvement of cognition in patients undergoing carotid endarterectomy

BACKGROUND

To determine the predictive value of carotid plaque characteristics for the improvement of cognition in patients with moderate-to-severe carotid stenosis after carotid endarterectomy (CEA), using vessel wall magnetic resonance imaging (MRI).

METHODS

This was a prospective cohort study. Patients with unilateral, moderate-to-severe carotid stenosis referred to the Peking University Third Hospital for CEA were prospectively recruited and underwent carotid vessel wall MRI within 1 week before CEA. We performed Montreal Cognitive Assessment (MoCA) within 1 week before and 3-4 days after CEA. The morphological and compositional characteristics of carotid plaques on MRI were evaluated. Improvement of cognition was defined as >10% increase of the total MoCA score after CEA compared with baseline. Carotid plaque characteristics were compared between patients with and without cognitive improvement.

RESULTS

In total, 105 patients (91 males; mean age, 65.5±8.4 years) were included. The volume {48.0 [interquartile range (IQR), 21.0 to 91.6] vs. 16.3 (IQR, 8.1 to 53.1) mm3; P=0.005} and cumulative slice [4.0 (IQR, 3.0 to 7.0) vs. 3.0 (IQR, 2.0 to 5.0); P=0.019] of carotid calcification, and maximum percentage of calcification area [13.1% (IQR, 6.0% to 19.8%) vs. 6.2% (IQR, 3.7% to 10.8%); P=0.004] were significantly smaller in participants with cognitive improvement compared to those without. Univariate logistic regression analysis showed that volume [odds ratio (OR) =0.994; 95% confidence interval (CI): 0.989 to 1.000; P=0.043] and cumulative slice (OR =0.823; 95% CI: 0.698 to 0.970; P=0.020) of carotid calcification, and maximum percentage of calcification area (OR =0.949; 95% CI: 0.909 to 0.991; P=0.018) were significantly correlated with cognitive improvement. After adjusting for confounding factors, these associations remained statistically or marginally significant (volume: OR =0.994; 95% CI: 0.988 to 1.000; P=0.057; maximum percentage of calcification area: OR =0.937; 95% CI: 0.890 to 0.987; P=0.014; and cumulative slice: OR =0.791; 95% CI: 0.646 to 0.967; P=0.022). No significant associations were found between other plaque characteristics and cognitive improvement (all P>0.05).

CONCLUSIONS

More than half of the participants with unilateral, moderate-to-severe carotid atherosclerotic stenosis had cognitive improvement. The size of calcification might be an effective indicator of cognitive improvement after CEA.

Association between carotid revascularization for asymptomatic stenosis and cognitive functions

Summary: Asymptomatic carotid stenosis (ACS) can cause cognitive dysfunction, related to cerebral hypoperfusion and microemboli. These mechanisms could be treated by carotid revascularization, but the impact of carotid angioplasty stenting (CAS) or carotid endarterectomy (CEA) on cognitive functions remains unclear. The aim of this systematic review was to realize a report on the actual state of results about asymptomatic carotid stenosis revascularization and cognitive function. We performed a systematic literature review to analyze all studies assessing the impact of asymptomatic carotid stenosis revascularizations on cognitive functions. We reviewed all publications published in Medline database and Cochrane between January 2010 and January 2020 including subjects with a cognitive evaluation and receiving carotid revascularization for asymptomatic stenosis. We identified 567 records for review, and finally we included in the systematic review 20 studies about ACS revascularization and cognitive functions. Only observational studies analyzed the impact of CEA and CAS on cognitive functions. Thus, too heterogeneous data associated to the lack of randomized controlled trials with an evaluation of optimal medical treatment did not enable to affirm the interest of the revascularization management of ACS in cognitive domain. There was a lack of standardization and finally studies were too heterogeneous to conclude on the impact of carotid revascularization on cognitive functions. There is an urgent need to harmonize research in this domain in order to prevent and treat cognitive dysfunction related to ACS, especially in our society with an aging population.

The microbiota-gut-brain axis participates in chronic cerebral hypoperfusion by disrupting the metabolism of short-chain fatty acids

BACKGROUND

Chronic cerebral hypoperfusion (CCH) underlies secondary brain injury following certain metabolic disorders and central nervous system (CNS) diseases. Dysregulation of the microbiota-gut-brain axis can exacerbate various CNS disorders through aberrantly expressed metabolites such as short-chain fatty acids (SCFAs). Yet, its relationship with CCH remains to be demonstrated. And if so, it is of interest to explore whether restoring gut microbiota to maintain SCFA metabolism could protect against CCH.

RESULTS

Rats subjected to bilateral common carotid artery occlusion (BCCAO) as a model of CCH exhibited cognitive impairment, depressive-like behaviors, decreased gut motility, and compromised gut barrier functions. The 16S ribosomal RNA gene sequencing revealed an abnormal gut microbiota profile and decreased relative abundance of some representative SCFA producers, with the decreased hippocampal SCFAs as the further evidence. Using fecal microbiota transplantation (FMT), rats recolonized with a balanced gut microbiome acquired a higher level of hippocampal SCFAs, as well as decreased neuroinflammation when exposed to lipopolysaccharide. Healthy FMT promoted gut motility and gut barrier functions, and improved cognitive decline and depressive-like behaviors by inhibiting hippocampal neuronal apoptosis in BCCAO rats. Long-term SCFA supplementation further confirmed its neuroprotective effect in terms of relieving inflammatory response and hippocampal neuronal apoptosis following BCCAO.

CONCLUSION

Our results demonstrate that modulating the gut microbiome via FMT can ameliorate BCCAO-induced gut dysbiosis, cognitive decline, and depressive-like behaviors, possibly by enhancing the relative abundance of SCFA-producing floras and subsequently increasing SCFA levels. Video abstract.

A systematic review of cognitive function after carotid endarterectomy in asymptomatic patients

OBJECTIVE

Asymptomatic carotid stenosis has been associated with a progressive decline in neurocognitive function. However, the effect of carotid endarterectomy on this process is poorly understood. We aimed to evaluate pre and post-operative cognitive function changes in asymptomatic patients after carotid endarterectomy METHODS: A systematic review of the existing reports in PubMed/MEDLINE, Embase, and Cochran databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement recommendations. All original retrospective or prospective studies (including cohort, cross-sectional, case-control, pilot studies, etc.) and clinical trials that compared pre and post-operative neurocognitive function in asymptomatic patients with carotid stenosis after CEA, which were published from January 2000 to April 2021 were identified and considered eligible for inclusion in the study.

RESULTS

Thirteen studies (502 CEAs) comparing cognitive function changes before and after CEA were identified. In seven studies with a total number of 272 patients, a mean age range of 67.3 ± 4.8 to 76.35 years old and after follow-up ranging between 1 and 12 months, overall cognitive function improved after CEA. However, in six studies with a total sample of 230, a mean age range of 68.6 ± 6.9 to 74.4±6.1 years, and follow-up ranged from 24 hours to 3 years, showed no change or decline in overall cognitive function after procedures.

CONCLUSIONS

The lack of standardization of specific cognitive tests and cognitive function assessment timing after CEA does not allow for definite conclusions to be made. However, improving the brain perfusion with combination of CEA and statin therapy may be a protective strategy against cognitive function decline.

Revascularization for asymptomatic carotid artery stenosis improves balance and mobility

OBJECTIVE

Balance and mobility function worsen with age, more so for those with underlying chronic diseases. We recently found that asymptomatic carotid artery stenosis (ACAS) restricts blood flow to the brain and might also contribute to balance and mobility impairment. In the present study, we tested the hypothesis that ACAS is a modifiable risk factor for balance and mobility impairment. Our goal was to assess the effect of restoring blood flow to the brain by carotid revascularization on the balance and mobility of patients with high-grade ACAS (≥70% diameter-reducing stenosis).

METHODS

Twenty adults (age, 67.0 ± 9.4 years) undergoing carotid endarterectomy for high-grade stenosis were enrolled. Balance and mobility assessments were performed before and 6 weeks after revascularization. These included the Short Physical Performance Battery, the Berg Balance Scale, the Four Square Step Test, the Dynamic Gait Index (DGI), the Timed Up and Go test, gait speed, the Mini-Balance Evaluation Systems Test (Mini-BESTest), and the Walking While Talking complex test.

RESULTS

Consistent with our previous findings, patients demonstrated reduced scores on the Short Physical Performance Battery, Berg Balance Scale, DGI, and Timed Up and Go test and in gait speed. Depending on the outcome measure, 25% to 90% of the patients had scored in the impaired range at baseline. After surgery, significant improvements were observed in the outcome measures that combined walking with dynamic movements, including the DGI (P = .02) and Mini-BESTest (P = .002). The proportion of patients with Mini-BESTest scores indicating a high fall risk had decreased significantly from 90% (n = 18) at baseline to 40% (n = 8) after surgery (P = .02). We used Pearson's correlations to examine the relationship between balance and mobility before surgery and the change after surgery. Patients with lower baseline DGI and Mini-BESTest scores demonstrated the most improvement after surgery (r = -0.59, P = .006; and r = -0.70, P = .001, respectively).

CONCLUSIONS

Carotid revascularization improved patients' balance and mobility, especially for measures that combine walking and dynamic movements. The greatest improvements were observed for the patients who had been most impaired at baseline.

Editor's Choice - Asymptomatic Carotid Stenosis and Cognitive Impairment: A Systematic Review

OBJECTIVE

The aim was to evaluate the relationship between asymptomatic carotid stenosis (ACS) of any severity and cognitive impairment and to determine whether there is evidence supporting an aetiological role for ACS in the pathophysiology of cognitive impairment.

DATA SOURCES

PubMed/Medline, Embase, Scopus, and the Cochrane library.

REVIEW METHODS

This was a systematic review (35 cross sectional or longitudinal studies) RESULTS: Study heterogeneity confounded data interpretation, largely because of no standardisation regarding cognitive testing. In the 30 cross sectional and six longitudinal studies (one included both), 33/35 (94%) reported an association between any degree of ACS and one or more tests of impaired cognitive function (20 reported one to three tests with poorer cognition; 11 reported four to six tests with poorer cognition, while three studies reported seven or more tests with poorer cognition). There was no evidence that ACS caused cognitive impairment via silent cortical infarction, or via involvement in the pathophysiology of lacunar infarction or white matter hyperintensities. However, nine of 10 studies evaluating cerebral vascular reserve (CVR) reported that ACS patients with impaired CVR were significantly more likely to have cognitive impairment and that impaired CVR was associated with worsening cognition over time. Patients with severe ACS but normal CVR had cognitive scores similar to controls.

CONCLUSION

Notwithstanding significant heterogeneity within the constituent studies, which compromised overall interpretation, 94% of studies reported an association between ACS and one or more tests of cognitive impairment. However, "significant association" does not automatically imply an aetiological relationship. At present, there is no clear evidence that ACS causes cognitive impairment via silent cortical infarction (but very few studies have addressed this question) and no evidence of ACS involvement in the pathophysiology of white matter hyperintensities or lacunar infarction. There is, however, better evidence that patients with severe ACS and impaired CVR are more likely to have cognitive impairment and to suffer further cognitive decline with time.

Gait and Balance Disorder in Patients with Transient Ischemic Attack or Minor Stroke

PURPOSE

Transient ischemic attack (TIA) and minor stroke had a high recurrence rate, resulting in potential neurological impairment. Only a few previous studies focused on gait and balance disorder in TIA and minor stroke. This study aimed to explore the relationship between gait and balance disorder and TIA/minor stroke.

PATIENTS AND METHODS

Eighty-two patients with TIA/minor stroke and fifty-two healthy control participants were recruited. The gait and balance function of the two groups was tested with six measurements (Four Square Step, Tandem, Functional Reach, Gait and Pivot Turn, Timed "Up and Go", and Single Leg Balance tests). The associations between these measures and TIA/minor stroke were determined through linear and logistic regression analyses.

RESULTS

There were no significant group differences in age, gender, body mass index, vision, and cognitive function. People with TIA/minor stroke had poorer performance in all six gait and balance measures (all p<0.05). Logistic regression analysis showed TIA/minor stroke was strongly associated with gait and balance disorder (Four Square Step Test [OR, 24.07; 95% CI 5.90-98.13; p<0.001], Tandem Test [OR, 5.50; 95% CI 1.64-18.40; p=0.006], Functional Reach Test [OR, 4.25; 95% CI 1.04-17.33; p=0.044], Gait and Pivot Turn Test [OR, 3.78; 95% CI 1.22-11.31; p=0.021], Timed"Up and Go"Test [OR, 15.79; 95% CI 2.32-107.48; p=0.005], and Single Leg Balance Test [OR, 8.96; 95% CI 2.34-34.01; p=0.001]). TIA/minor stroke patients with older age, cognitive dysfunction, high K-CRP level, and severe atherosclerosis in lower limbs were more likely to have gait and balance disorder.

CONCLUSION

Our findings highlight the significant relationship between gait and balance disorder and TIA/minor stroke. It seems that people with TIA/minor stroke had a higher possibility to get gait and balance disorder. Gait and balance disorder following a minor stroke or TIA may be attributed to cognitive function in these patients.

Asymptomatic carotid artery stenosis is associated with cerebral hypoperfusion

OBJECTIVE

We have shown that almost 50% of patients with asymptomatic carotid stenosis (ACS) will demonstrate cognitive impairment. Recent evidence has suggested that cerebral hypoperfusion is an important cause of cognitive impairment. Carotid stenosis can restrict blood flow to the brain, with consequent cerebral hypoperfusion. In contrast, cross-hemispheric collateral compensation through the Circle of Willis, and cerebrovascular vasodilation can also mitigate the effects of flow restriction. It is, therefore, critical to develop a clinically relevant measure of net brain perfusion in patients with ACS that could help in risk stratification and in determining the appropriate treatment. To determine whether ACS results in cerebral hypoperfusion, we developed a novel approach to quantify interhemispheric cerebral perfusion differences, measured as the time to peak (TTP) and mean transit time (MTT) delays using perfusion-weighted magnetic resonance imaging (PWI) of the whole brain. To evaluate the utility of using clinical duplex ultrasonography (DUS) to infer brain perfusion, we also assessed the relationship between the PWI findings and ultrasound-based peak systolic velocity (PSV).

METHODS

Structural and PWI of the brain and magnetic resonance angiography of the carotid arteries were performed in 20 patients with ≥70% ACS. DUS provided the PSV, and magnetic resonance angiography provided plaque geometric measures at the stenosis. Volumetric perfusion maps of the entire brain from PWI were analyzed to obtain the mean interhemispheric differences for the TTP and MTT delays. In addition, the proportion of brain volume that demonstrated a delay in TTP and MTT was also measured. These proportions were measured for increasing severity of perfusion delays (0.5, 1.0, and 2.0 seconds). Finally, perfusion asymmetries on PWI were correlated with the PSV and stenosis features on DUS using Pearson's correlation coefficients.

RESULTS

Of the 20 patients, 18 had unilateral stenosis (8 right and 10 left) and 2 had bilateral stenoses. The interhemispheric (left-right) TTP delays measured for the whole brain volume identified impaired perfusion in the hemisphere ipsilateral to the stenosis in 16 of the 18 patients. More than 45% of the patients had had ischemia in at least one half of their brain volume, with a TTP delay >0.5 second. The TTP and MTT delays showed strong correlations with PSV. In contrast, the correlations with the percentage of stenosis were weaker. The correlations for the PSV were strongest with the perfusion deficits (TTP and MTT delays) measured for the whole brain using our proposed algorithm (r = 0.80 and r = 0.74, respectively) rather than when measured on a single magnetic resonance angiography slice as performed in current clinical protocols (r = 0.31 and r = 0.58, respectively).

CONCLUSIONS

Interhemispheric TTP and MTT delay measured for the whole brain using PWI has provided a new tool for assessing cerebral perfusion deficits in patients with ACS. Carotid stenosis was associated with a detectable reduction in ipsilateral brain perfusion compared with the opposite hemisphere in >80% of patients. The PSV measured at the carotid stenosis using ultrasonography correlated with TTP and MTT delays and might serve as a clinically useful surrogate to brain hypoperfusion in these patients.

A New Rat Model of Chronic Cerebral Hypoperfusion Resulting in Early-Stage Vascular Cognitive Impairment

Objective

Currently, most models of vascular cognitive impairment are established by occluding the carotid arteries uni- or bilaterally to reduce the cerebral blood flow mimicking chronic cerebral hypoxia. Due to the sudden blood flow interruption, a gradual narrowing of the carotid artery cannot be completely imitated. This paper aims to establish a bilateral carotid stenosis model with mild cognitive dysfunction and mild white matter changes to simulate patients with vascular predementia.

Methods

Aged Wistar rats (18 months old) underwent either bilateral common carotid artery stenosis (BCAS) or occlusion (BCAO) surgery or a sham operation (control group). The cerebral blood flow in the frontal cortex was measured using Doppler flowmetry. Thirty days after surgery, cognitive function impairments were determined with the Morris water maze; cerebral magnetic resonance imaging was performed to detect changes in fractional anisotropy to assess white matter injuries, and histological studies were performed.

Results

The aged rats in the BCAS group showed a more gradual cerebral blood flow reduction and a lower mortality rate (11%) compared to rats in the BCAO group. The water maze test revealed a more marginal impairment affecting spatial learning and memory in rats with BCAS than in rats with BCAO. Diffusion tensor imaging detected white matter injuries in the hippocampus and cerebral cortex of BCAS rats. Particularly, a small portion of nerve fibers of the lateral somatosensory cortex was significantly different between rats of the BCAO and BCAS groups. In the BCAS group, the microscopic structure of the hippocampal CA1 region changed slightly after 30 days and sustained a slight mitochondrial crista crack. Fluorescence staining indicated that the number of GFAP-positive cells was increased in rat brains of the BCAS group, and this phenomenon was even more pronounced in the BCAO group. The hnRNPA2/B1 and GABA_AR-α1 expression levels were significantly decreased in the hippocampus of rats with BCAS compared to those of controls.

Conclusion

Severe bilateral carotid stenosis induced mild cognitive dysfunction and slight structural changes in the brains of aged rats. Thus, a chronic cerebral hypoperfusion model was successfully established.

Animal Models of Chronic Cerebral Hypoperfusion: From Mouse to Primate

Vascular cognitive impairment (VCI) or vascular dementia occurs as a result of brain ischemia and represents the second most common type of dementia after Alzheimer’s disease. To explore the underlying mechanisms of VCI, several animal models of chronic cerebral hypoperfusion have been developed in rats, mice, and primates. We established a mouse model of chronic cerebral hypoperfusion by narrowing the bilateral common carotid arteries with microcoils, eventually resulting in hippocampal atrophy. In addition, a mouse model of white matter infarct-related damage with cognitive and motor dysfunction has also been established by asymmetric common carotid artery surgery. Although most experiments studying chronic cerebral hypoperfusion have been performed in rodents because of the ease of handling and greater ethical acceptability, non-human primates appear to represent the best model for the study of VCI, due to their similarities in much larger white matter volume and amyloid β depositions like humans. Therefore, we also recently developed a baboon model of VCI through three-vessel occlusion (both the internal carotid arteries and the left vertebral artery). In this review, several animal models of chronic cerebral hypoperfusion, from mouse to primate, are extensively discussed to aid in better understanding of pathophysiology of VCI.