Increased Intima Media Thickness and Atherosclerotic Plaques in the Carotid Artery as Risk Factors for Silent Brain Infarcts

Novel Biomarkers and Imaging Indices for the "Vulnerable Patient" with Carotid Stenosis: A Single-Center Study

BACKGROUND

We investigated the relationship of matrix metalloproteinases (MMPs), cardio-ankle vascular index (CAVI), and Gray-Scale Median (GSM) score with the severity and vulnerability of carotid atherosclerosis and major adverse cardiovascular events (MACE) during follow-up of carotid artery revascularization.

METHODS

We enrolled 262 patients undergoing carotid revascularization therapy (GRT), 109 asymptomatic patients with low-grade carotid stenosis (40-70%) receiving conservative treatment (GCT), and 92 age- and sex-matched control subjects without carotid atherosclerosis (GCO). All participants underwent carotid ultrasound and we assessed at baseline clinical parameters, metabolic profile, CAVI, GSM, and circulating levels of hsCRP, MMP-3,-7,-9, and TIMP-1.

RESULTS

Both GRT and GCT presented with elevated CAVI, MMPs, and TIMP-1 levels compared to GCO (p < 0.001). The escalation highly correlated to the presence of symptoms or paralleled the degree of carotid stenosis (p < 0.001). During follow-up (mean duration: 55 months), 51 GRT patients experienced MACE unrelated to the revascularization procedure. Within GRT, diabetes (HR: 2.07; CI: 1.55-2.78, p < 0.001), smoking (HR: 1.67; CI: 1.35-1.95, p < 0.001), high CAVI (HR: 1.22; CI: 1.09-1.43, p = 0.023) and MMP-9 (HR: 1.44; CI: 1.29-2.15, p = 0.005), and low GSM (HR: 1.40; CI: 1.16-2.12, p = 0.002) independently predicted MACE occurrences, despite the optimum medical therapy.

CONCLUSIONS

Novel imaging and biochemical biomarkers were positively associated with atherosclerosis severity, while CAVI, MMP-9, and low GSM showed a positive, independent relationship with MACE after carotid revascularization, describing "vulnerable patients".

Quantitative comparison between carotid plaque hardness and histopathological findings: an observational study

Background

Plaque hardness in carotid artery stenosis correlates with cerebral infarction. This study aimed to quantitatively compare plaque hardness with histopathological findings and identify the pathological factors involved in plaque hardness.

Methods

This study included 84 patients (89 lesions) undergoing carotid endarterectomy (CEA) at our institution. Plaque hardness was quantitatively measured immediately after excision using a hardness meter. Collagen and calcification were evaluated as the pathological factors. Collagen was stained with Elastica van Gieson stain, converted to a gray-scale image, and displayed in a 256-step histogram. The median gray-scale median (GSM) was used as the collagen content. The degree of calcification was defined by the hematoxylin–eosin stain as follows: "0:" no calcification, "1:" scattered microcalcification, or "2:" calcification greater than 1 mm or more than 2% of the total calcification. Carotid echocardiographic findings, specifically echoluminance or the brightness of the narrowest lesion of the plaque, classified as hypo-, iso-, or hyper-echoic by comparison with the intima-media complex surrounding the plaque, and clinical data were reviewed.

Results

Plaque hardness was significantly negatively correlated with GSM [Spearman's correlation coefficient: -0.7137 (p < 0.0001)]: the harder the plaque, the higher the collagen content. There were significant differences between plaque hardness and degree of calcification between "0" and "2" (p = 0.0206). For plaque hardness and echoluminance (hypo-iso-hyper), significant differences were found between hypo-iso (p = 0.0220), hypo-hyper (p = 0.0006), and iso-hyper (p = 0.0015): the harder the plaque, the higher the luminance. In single regression analysis, GSM, sex, and diabetes mellitus were significant variables, and in multiple regression analysis, only GSM was extracted as a significant variable.

Conclusions

Plaque hardness was associated with a higher amount of collagen, which is the main component of the fibrous cap. Greater plaque hardness was associated with increased plaque stability. The degree of calcification may also be associated with plaque hardness.

Association of Carotid Intima-Media Thickness with Brain MRI Markers in the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS)

OBJECTIVE

Elevated carotid intima-media thickness (cIMT) and carotid plaque are markers of arterial injury and may be linked to structural brain injury. We hypothesized cIMT or presence of carotid plaque at midlife are associated with presence of infarcts and cerebral microbleeds, greater white matter hyperintensity (WMH) volume, and smaller regional brain volumes in late-life.

METHODS

We included 1,795 Atherosclerosis Risk in Communities (ARIC) Study participants (aged 57±6 years, 57% female, 23% Black) with carotid ultrasounds in 1990-1992 and brain MRI scans in 2011-2013. Weighted linear regression was used for brain volume outcomes, while logistic regression was used for infarcts and cerebral microbleeds.

RESULTS

After multivariable adjustments, the highest cIMT quintile was associated with smaller deep gray matter (β [95% CI]: -0.11 [-0.22, -0.01]) and cortical volume in a temporal-parietal meta region of interest (ROI) (β [95% CI]: -0.10 [-0.20, -0.01]) in late-life. Similarly, those with carotid plaque had smaller regional brain volumes than those without (βs [95% CIs]: -0.05 [-0.12, 0.03] and -0.06 [-0.13, 0.01] for deep gray matter and temporal-parietal meta ROI). No significant relations were observed with WMH volume, infarcts, or cerebral microbleeds.

CONCLUSION

Over a median follow-up of 21 years, greater midlife cIMT and presence of carotid plaque were associated with smaller deep gray matter volume and cortical volume in a meta ROI involving temporal and parietal lobe regions typically involved in neurodegeneration, including Alzheimer's disease, in later life. Contrary to our hypothesis, associations between measures of arterial injury and markers of vascular brain injury were null.

Silent brain infarcts and white matter lesions in patients with asymptomatic carotid stenosis

The association of carotid atherosclerosis with silent brain infarcts (SBIs) and white matter lesions (WMLs) currently remains unknown. This study aims to compare SBIs, deep white matter lesions (DWMLs), and periventricular white matter lesions (PWMLs) in ipsilateral and contralateral hemispheres to internal carotid artery (ICA) stenosis, and investigate their association with stenosis grade in patients with asymptomatic ≥ 50% unilateral extracranial ICA stenosis. Patients without previous history of stroke and/or transient ischemic attack who had ≥ 50% stenosis in unilateral ICA on carotid color Doppler ultrasound were enrolled in the study. Patient demographics, vascular risk factors and ICA stenosis grades; number, location, and size of SBIs, DWMLs, and PWMLs in ICA territory were evaluated in both hemispheres using magnetic resonance imaging of the brain. Of the 69 patients, 53 had 50-69% (76.8%) and 16 had ≥ 70% (23.2%) unilateral ICA stenosis. There was no statistically significant difference in SBIs between ipsilateral and contralateral hemispheres to ≥ 50% ICA stenosis. Comparison of ICA stenoses as 50-69% and ≥ 70% revealed a greater number of patients with SBI in ipsilateral hemisphere to ≥ 70% stenosis compared to contralateral (p = 0.025). The number of SBIs was also higher in ipsilateral hemisphere to ≥ 70% stenosis compared to contralateral (p = 0.022). While DWMLs and PWMLs did not differ between hemispheres, frequency of Fazekas grade 1 DWMLs was lower in ipsilateral hemisphere to either 50-69% or ≥ 70% ICA stenosis compared to contralateral (p = 0.035 and p = 0.025, respectively). Results of the present study indicate that stenosis grade may be relevant in the association between asymptomatic carotid stenosis and SBIs, and ≥ 70% stenosis may pose a risk of SBI development.

Carotid artery intima-media thickness, HDL cholesterol levels, and gender associated with poor visual acuity in patients with branch retinal artery occlusion

PURPOSE

To investigate factors associated with poor visual acuity (VA) in branch retinal artery occlusion (BRAO).

METHODS

This was a retrospective cross-sectional study of 72 eyes with BRAO of 72 patients. For statistical comparison, we divided the patients into worse-VA (decimal VA < 0.5) and better-VA (decimal VA > = 0.5) groups. We examined the association of clinical findings, including blood biochemical test data and carotid artery ultrasound parameters, with poor VA.

RESULTS

Median age, hematocrit, hemoglobin and high-density lipoprotein (HDL) differed significantly between the groups (P = 0.018, P < 0.01, P < 0.01, and P = 0.025). There was a tendency towards higher median IMT-Bmax in the worse-VA group (worse-VA vs. better-VA: 2.70 mm vs. 1.60 mm, P = 0.152). Spearman's rank correlation test revealed that logMAR VA was significantly correlated to IMT-Bmax (rs = 0.31, P < 0.01) and IMT-Cmax (rs = 0.24, P = 0.035). Furthermore, logMAR VA was significantly correlated to HDL level (rs = -0.33, P < 0.01). Multivariate logistic regression analysis revealed that IMT-Bmax (odds ratio [OR] = 2.70, P = 0.049), HDL level (OR = 0.91, P = 0.032), and female gender (OR = 15.63, P = 0.032) were independently associated with worse VA in BRAO.

CONCLUSIONS

We found that increased IMT-Bmax, decreased HDL, and female sex were associated with poor VA in BRAO patients. Our findings might suggest novel risk factors for visual dysfunction in BRAO and may provide new insights into the pathomechanisms underlying BRAO.

Brain imaging biomarkers of carotid artery disease

Extracranial carotid artery atherosclerotic disease is a major contributor to ischemic stroke. Carotid atherosclerotic disease can present with a spectrum of findings ranging from mild carotid intima-media thickness to high-risk vulnerable carotid plaque features and carotid stenosis. Before leading to clinically overt stroke or transient ischemic attack, there may be other markers of downstream ischemia secondary to carotid atherosclerotic disease. In this review article, we will review some of the imaging findings that may be seen downstream to carotid artery disease on various imaging modalities, including hemodynamic and perfusional abnormalities which may be seen on CT, MR, or using other advanced imaging techniques, white matter hyperintensities on brain imaging, silent or covert brain infarctions, cerebral microbleeds, and regional and generalized cerebral volume loss. Many of these imaging findings are seen routinely on brain magnetic resonance imaging in patients without overt clinical symptoms. Despite frequently being asymptomatic, many of these imaging findings are also strongly associated with increased risk of future stroke, cognitive impairment, and even mortality. We will review the existing evidence underpinning the associations between these frequently encountered imaging findings and carotid artery atherosclerotic disease. Future validation of these imaging findings could lead to them being powerful biomarkers of cerebrovascular health.

Asymptomatic carotid stenosis and concomitant silent brain infarctions

Objectives

This review aims to clarify (1) the definition of silent brain infarct (SBI), (2) the diagnostic criteria of SBI using magnetic resonance imaging (MRI), (3) the prevalence of patients with asymptomatic carotid stenosis and SBI based on MRI assessment, (4) the association of SBI and asymptomatic carotid stenosis and the risk of stroke compared to patients without SBI, (5) the association between development of dementia/cognitive impairment in people with asymptomatic carotid stenosis and SBI, and (6) the evidence for treating patients with carotid stenosis and SBI.

Methods

A systematic search of PubMed and Scopus including all studies published from 2000 to 2018 and written in English.

Results

No consensus of the definition and diagnostic criteria for SBI was found. The prevalence of SBI in asymptomatic carotid patients is 17–33.3%. SBI is a significant risk factor for future stroke, OR 4.6 (95% CI: 3.0–7.2; p < 0.0001). One substudy showed that immediate CEA is beneficial compared to delayed CEA in these patients, showing a 45% reduction in annual stroke rate from 1.5%/year to 0.7%/year.

Conclusion

This review emphasizes the need to standardize the definition and diagnostic criteria of SBI on MRI. Current evidence suggests an increased risk and a small potential benefit of offering carotid endarterectomy to patient with silent brain infarct. Prospective studies are warranted to elucidate these issues further.

High triglyceride/HDL cholesterol ratio is associated with silent brain infarcts in a healthy population

Background

Triglycerides (TG)/high-density lipoprotein (HDL) cholesterol ratio is a marker of small/dense low-density lipoprotein particles, which are closely associated with various metabolic and vascular diseases. However, the role of TG/HDL cholesterol ratio in cerebrovascular diseases has not been well studied. In this study, we evaluated the relationship between TG/HDL cholesterol ratio and the presence of silent brain infarct (SBI) in a neurologically healthy population.

Methods

We retrospectively evaluated consecutive participants in health check-ups between January 2006 and December 2013. SBI was defined as an asymptomatic, well-defined lesion with a diameter of ≥3 mm on T1- or T2-weighted images. TG/HDL cholesterol ratio was calculated after dividing absolute TG levels by absolute HDL cholesterol levels.

Results

Of 3172 healthy participants, 263 (8.3%) had SBI lesions. In multivariate analysis, TG/HDL cholesterol ratio was independently associated with SBI (adjusted odds ratio [aOR] = 1.16, 95% confidence interval [CI] = 1.00 to 1.34, P = 0.047). This association was prominent in males (aOR = 1.23, 95% CI = 1.03 to 1.48, P = 0.021), but not in females. In the analyses of the relationships between lipid parameters and SBI lesion burden, TG/HDL cholesterol ratio was positively correlated, and total cholesterol/TG ratio was negatively correlated with SBI lesion burden, in dose-response manners (P for trend = 0.015 and 0.002, respectively).

Conclusions

The TG/HDL cholesterol ratio was positively associated with the prevalence of SBI in a neurologically healthy population.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1373-8) contains supplementary material, which is available to authorized users.

Carotid Intima-Media Thickness and Silent Brain Infarctions in a Biracial Cohort: The Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Both hypertensive and atherosclerotic processes contribute to common carotid artery intima-media thickness (CCA-IMT). Elevated CCA-IMT may be indicative of subclinical cerebrovascular disease; however, its role in the absence of concomitant carotid artery plaque is uncertain, and few studies have examined associations in Black populations.

MATERIALS AND METHODS

At cohort visit 3 (1993-1995) a subset of stroke-free participants (641 Blacks and 702 Whites, mean age 63) from the Atherosclerosis Risk in Communities (ARIC) study was imaged by brain MRI and carotid ultrasound. A CCA-IMT >0.9 mm was considered elevated. Asymptomatic brain lesions ≥3 mm were considered silent brain infarctions (SBI). Subcortical SBI measuring 3 to <20 mm were considered lacunes. Associations between elevated CCA-IMT and SBI were analyzed with Poisson regression.

RESULTS

Elevated CCA-IMT was identified in 168 participants (16% of Blacks, 10% of Whites), and SBI were observed in 156 (15% of Blacks, 8% of Whites). Elevated CCA-IMT was strongly related to anterior circulation SBI, posterior circulation SBI, and lacunes. After adjustments, elevated CCA-IMT remained associated with greater number of lacunes in Blacks ([prevalence ratio, PR] = 1.60; 95% confidence interval [CI]: 1.02-2.51), but not Whites (PR = 0.85; 95% CI: 0.35-2.04); P value for interaction = 0.12. Among Black participants without concomitant carotid plaque, elevated CCA-IMT was associated with twice the number of lacunes (PR = 2.00; 95% CI: 1.05-3.82).

CONCLUSIONS

In older Black adults, elevated CCA-IMT is independently associated with lipohyalinosis of the cerebral small vessels, irrespective of concomitant carotid plaque and vascular risk factors.

Predictive Factors of Silent Brain Infarcts after Asymptomatic Carotid Endarterectomy

BACKGROUND

The optimization of medical treatment regularly challenges the role of carotid surgery for asymptomatic patients. Current research seeks to determine which of these patients will benefit most from surgery. The goal of this study was to identify in a multicenter study, using magnetic resonance imaging (MRI), the risk factors for postoperative silent cerebral ischemic lesions after carotid surgery for asymptomatic stenosis.

METHODS

The multicenter, retrospective study included patients with asymptomatic severe carotid stenosis suitable for surgical treatment and who did not have a history of cerebral ischemia. A diffusion MRI scan was performed the day before and in the 3 days after the procedure. An analysis by an independent neuroradiologist determined the presence of preoperative silent ischemia and the appearance of new lesions postoperatively. The analysis also took into account the plaque type, lesions of supra-aortic trunks, the circle of Willis, the type of surgery, and anesthesia, shunt use, and clamp time.

RESULTS

Between April 2011 and November 2015, 141 patients were included. The mean degree of carotid stenosis in the patients who underwent surgery was 78.2% ± 6.5, with 9 (6.4%) cases of contralateral stenosis ≥70% and 6 (4.3%) of which were thrombosis. The circle of Willis was incomplete in 23 (16.3%) patients. Twenty-one (14.9%) plaques were of high embolic risk. The preoperative MRI found 34 (24.1%) patients with embolic ischemic lesions. The majority of procedures were eversions performed under general anesthesia, 7 (5%) required a shunt, and the mean clamp time was 39 ± 16 min. The postoperative MRI revealed that 10 (7%) patients had a new ischemic lesion on the operated side. None of these lesions were symptomatic. On multivariate analysis, the risk factors for appearance of a new ischemic lesion on the operated side were significant severe stenosis of the vertebral artery ipsilateral to the lesion (odds ratio [OR] = 9.2, 95% confidence interval [CI] [2.1-39.8], P = 0.003) and insertion of a shunt (OR = 9.1, 95% CI [1.1-73.1], P = 0.039). The 30-day follow-up showed one death at D4 due to hemorrhagic stroke on the operated side and one contralateral stroke. None of the study patients had a myocardial infarction.

CONCLUSIONS

In this multicenter study, the rate of silent ischemic lesions in asymptomatic carotid surgery showed 43.3% of preoperative silent ischemic lesions and 9.2% of new silent lesions after surgery. The use of a shunt and presence of ipsilateral vertebral stenosis are risk factors for perioperative embolism.

Clinical significance of the coexistence of carotid artery plaque and white matter disease in patients with symptomatic cerebral infarction

OBJECTIVES

Symptomatic cerebral infarction (CI) can occur in patients without main cerebral artery stenosis or occlusion. This study investigated the unique features of carotid artery plaque and white matter disease (WMD) in patients with symptomatic CI and transient ischemic attack (TIA) but without stenosis or occlusion of a main cerebral artery.

PATIENTS AND METHODS

We studied 647 patients who underwent both carotid ultrasound examination and brain magnetic resonance images. Plaque score (PS), plaque number, maximal plaque intima-media thickness and grades of WMD were examined. Subjects were divided into four groups, the CI group, TIA group, myocardial infarction (MI) group and risk factor (RF) group. Plaque and WMD were analyzed in cerebral ischemia group (CI and TIA), compared to non-cerebral ischemia groups and to a high PS group and a high WMD grade group from the RF group.

RESULTS

Both of each value of plaque and grades of WMD in the cerebral ischemia group were significantly higher than those in other groups. Grades of WMD in the cerebral ischemia group were significantly higher than those in the high PS group, although there was no significant difference of the each value of plaque between the two groups. The each value of plaque in the cerebral ischemia group was also significantly higher than those in the high WMD grade group, although there was no significant difference of grade of WMD between the two groups.

CONCLUSION

Simultaneous increases in carotid artery plaque and WMD are associated with symptomatic CI, which is not caused by stenosis or occlusion of a main cerebral artery.

Time dependent transition of the levels of protein-conjugated acrolein (PC-Acro), IL-6 and CRP in plasma during stroke

Objective

Measurement of plasma levels of protein-conjugated acrolein (PC-Acro) together with IL-6 and CRP can be used to identify silent brain infarction (SBI) with high sensitivity and specificity. The aim of this study was to determine how these biomarkers vary during stroke.

Methods

Levels of PC-Acro, IL-6 and CRP in plasma were measured on day 0, 2, 7 and 14 after the onset of ischemic or hemorrhagic stroke.

Results

After the onset of stroke, the level of PC-Acro in plasma was elevated corresponding to the size of stroke. It returned to near control levels by day 2, and remained similar through day 14. The degree of the decrease in PC-Acro on day 2 was greater when the size of brain infarction or hemorrhage was larger. An increase in IL-6 and CRP occurred after the increase in PC-Acro, and it was well correlated with the size of the injury following infarction or hemorrhage. The results suggest that acrolein becomes a trigger for the production of IL-6 and CRP, as previously observed in a mouse model of stroke and in cell culture systems. The increase in IL-6 and CRP was also correlated with poor outcome judging from mRS.

Conclusion

The results indicate that the degree of the decrease in PC-Acro and the increase in IL-6 and CRP from day 0 to day 2 was correlated with the size of brain infarction, and the increase in IL-6 and CRP with poor outcome at discharge.

The Association between Carotid Artery Atherosclerosis and Silent Brain Infarction: A Systematic Review and Meta-analysis

BACKGROUND

Carotid atherosclerosis is responsible for ~20% of ischemic strokes, but it is unclear whether carotid disease is associated with the presence of downstream silent brain infarction (SBI). We performed a systematic review and meta-analysis to study the relationship between SBI and 2 separate manifestations of carotid atherosclerosis, carotid intima-media thickening (IMT) and luminal stenosis.

METHODS

Ovid MEDLINE, Ovid Embase, and the Cochrane Library Database were searched with an additional search of references and citing articles of target studies. Articles were included if they reported an association between carotid IMT or stenosis and magnetic resonance imaging-defined SBI, excluding SBIs found after carotid intervention.

RESULTS

We pooled 7 studies of carotid IMT reporting on 1469 subjects with SBI and 5102 subjects without SBI. Subjects with SBI had a larger mean IMT than subjects without SBI (pooled standardized mean difference, .37; 95% confidence interval [CI], .23-.51; P < .0001). We pooled 11 studies of carotid stenosis reporting on 12,347 subjects (2110 subjects with carotid stenosis and 10,237 subjects without carotid stenosis). We found a higher prevalence of SBI among subjects with carotid stenosis (30.4% versus 17.4%). Our pooled random-effects analysis showed a significant positive relationship between carotid stenosis and SBI (odds ratio, 2.78; 95% CI, 2.19-3.52; P < .0001).

CONCLUSIONS

Two forms of atherosclerotic disease, carotid IMT and stenosis, are both significantly associated with SBI. This review highlights a lack of consistent definitions for carotid disease measures and little evidence evaluating SBI prevalence downstream from carotid stenosis.

Evaluation by Magnetic Resonance Imaging of Silent Brain Infarcts in Preoperative and Postoperative Asymptomatic Carotid Surgery

BACKGROUND

To report the prevalence of silent brain infarcts (SBI) at magnetic resonance imaging (MRI) before and after surgery for asymptomatic high grade carotid stenosis.

METHODS

This is a single center retrospective observational study. Asymptomatic patients who underwent carotid endarterectomy between October 2012 and October 2014 were included. The preoperative assessment included a Doppler and a computed tomographic (CT) scan dating less than 3 months. A neurological examination was performed during the anesthesia consultation and in the 15 days before surgery. An MRI angiography was performed the day before and 3 days after surgery and was analyzed by an independent neuroradiologist. Preoperative analysis focused on the presence of ischemic events at MRI. The type of plaque, the supra aortic trunk lesions, and the quality of the circle of Willis were analyzed using Doppler and CT scanning. Postoperatively, we searched for signs of postoperative ischemic events at MRI.

RESULTS

Forty-one patients were included (85.4% of men), and the mean age was 72.4 ± 8.3 years. We noted 7 (17.1%) contralateral stenoses (>50%) and 2 (4.9%) contralateral thromboses, 6 (14.6%) vertebral stenoses, and 7 (17.1%) abnormalities of the circle of Willis. The morphological analysis described 6 unstable plaques including 4 ulcerated, 1 pseudodissection, and 1 intraplaque hemorrhage. Preoperatively, we noted the presence of 21 (51.2%) ischemic lesions including 9 (21.9%) multiple lacunar ischemic events and 12 (29.3%) silent arterial territory infarcts. Eversion was performed for all patients except for 6 (14.6%), for whom a bypass was necessary. No deaths or major complications were observed in the 30 postoperative days. Postoperatively, MRI showed 3 (7.3%) asymptomatic recent ischemic strokes, 1 ipsilateral middle cerebral artery (MCA) stroke, and 2 contralateral (cerebellar and MCA) strokes.

CONCLUSIONS

Patients with asymptomatic significant carotid stenosis show many preoperative SBI indicating a significant embolic risk. It is difficult to conclude about intraoperative embolic risk, but we hope that more data could demonstrate the importance of MRI for the preoperative evaluation of carotid plaques and brain parenchyma, to identify high-risk embolic patients.

Comparison between Quantitative Stiffness Measurements and Ultrasonographic Findings of Fresh Carotid Plaques

Using a stiffness meter, we quantitatively measured the stiffness of fresh plaques that had been excised by carotid endarterectomy. The objective of this study was to clarify the correlation between plaque stiffness and pre-operative carotid ultrasonographic findings, and predict the stiffness of plaques before surgery by comparison with the stiffness of common items. The study population comprised 44 patients (44 lesions) who had undergone carotid endarterectomy at our institution between December 2009 and October 2014. The stiffness of excised fresh plaques was measured using a stiffness meter and compared with the pre-operative echographic findings for the plaques and the stiffness of selected foods and common items. The mean stiffness value for all plaques was 4.52 ± 3.30 MPa (mean ± standard deviation). The plaques exhibiting calcification were significantly harder (p = 0.001). On classification of lesions on the basis of echographic findings, plaque hardness was in the order low-echoic (15 lesions) < iso-echoic (20 lesions) < high-echoic (9 lesions) (p = 0.02). The stiffness of the low-echoic group was equivalent to that of tofu or sliced cheese, whereas the plaques in the iso- and high-echoic groups exhibited stiffness similar to that of ham and a plastic eraser, respectively. A significant correlation was observed between the quantitative stiffness values of carotid plaques and their brightness on carotid ultrasonography. Using these data, operators might be able to predict plaque stiffness from pre-operative echographic findings. In addition, it might be useful for operators to compare such quantitative stiffness measurements with stiffness data for foods and common items to gain an understanding of the state of the target plaque before treatment.

Correlation between brain damage, associated biomarkers, and medication in psychiatric inpatients: A cross-sectional study

BACKGROUND

We clarified the correlation between brain damage, associated biomarkers and medication in psychiatric patients, because patients with schizophrenia have an increased risk of stroke.

METHODS

The cross-sectional study was performed from January 2013 to December 2015. Study participants were 96 hospitalized patients (41 men and 55 women) in the Department of Psychiatry at Kohnodai Hospital, National Center for Global Health and Medicine, Ichikawa, Chiba, Japan. Patients were classified into schizophrenia (n=70) and mood disorders (n=26) by psychiatric diagnoses with DSM-IV-TR criteria.

RESULTS

The incidence of brain damage [symptomatic and silent brain infarctions (SBIs) and white matter hyperintensity (WMH)] was correlated more with mood disorders than with schizophrenia. It has been previously shown that the concentrations of protein-conjugated acrolein (PC-Acro) and interleukin-6 (IL-6) increased in plasma of brain infarction patients together with C-reactive protein (CRP). The concentration of PC-Acro was significantly higher in patients with mood disorders than in those with schizophrenia. The concentration of IL-6 in both groups was nearly equal to that in the control group, but that of CRP in both groups, especially in mood disorders, was higher than that in the control group. Accordingly, the relative risk value for brain infarction was higher in patients with mood disorders than with schizophrenia. Medication with atypical antipsychotics reduced PC-Acro significantly in all psychiatric patients and reduced IL-6 in mood disorder patients.

CONCLUSION

Measurement of 3 biomarkers (CRP, PC-Acro and IL-6) are probably useful for judgement of severity of brain damage and effectiveness of medication in psychiatric patients.

Carotid atherosclerosis, silent ischemic brain damage and brain atrophy: A systematic review and meta-analysis

BACKGROUND

The widespread use of brain imaging has led to increased recognition of subclinical brain abnormalities, including white matter hyperintensities (WMH) and silent brain infarctions (SBI), which have a vascular origin, and have been associated to a high risk of stroke, disability and dementia. Carotid atherosclerosis (CA) may be causative in the development of WMH, SBI and eventually brain atrophy. Aim of the present systematic review and meta-analysis was to assess the existing evidence linking CA to WMH, SBI and brain atrophy.

METHODS

The relation between CA and WMH, SBI and brain atrophy was investigated through the systematic search of online databases up to September 2015 and manual searching of references and related citations. Pooled estimates were calculated by random-effects model, using restricted maximum likelihood method with inverse variance weighting method.

RESULTS

Of the 3536 records identified, fifteen were included in the systematic review and 9 were found to be eligible for the meta-analysis. CA was significantly associated with the presence of WMH (Odds Ratio, OR 1.42, confidence interval, CI 1.22-1.66, p<0.0001) and of SBI (OR 1.89, CI 1.46-2.45, p<0.0001). No meta-analysis could be performed for the relation between CA and brain atrophy due to the lack of suitable studies.

CONCLUSIONS

CA was found to be associated to WMH and SBI. While no causative association can be inferred from the available data, the presence of carotid plaque may be considered a significant risk factor for subclinical cerebral damage.

Silent Brain Infarction in Patients With Asymptomatic Carotid Artery Atherosclerotic Disease

BACKGROUND AND PURPOSE

The relationship between carotid atherosclerosis and ipsilateral silent brain infarction (SBI) is unclear. We tested the hypothesis that extracranial internal carotid artery (ICA) stenosis is associated with a greater prevalence of SBI in the cerebral hemisphere ipsilateral to ICA disease compared with the unaffected, contralateral side.

METHODS

We identified patients with unilateral extracranial ICA stenosis ≥50% on angiography by standard imaging criteria. We included patients with recent brain magnetic resonance imaging who had no previous history of stroke or transient ischemic attack. Blinded readers ascertained the presence of anterior circulation SBIs. SBI was defined as either a cavitary lacunar infarction in the white or deep gray matter or cortical infarction defined by T2 hyperintense signal in cortical gray matter. The Wilcoxon signed-rank test was used to compare SBI in the cerebral hemispheres and Cohen κ to assess inter-rater reliability of SBI evaluation.

RESULTS

Among 104 patients, we found a higher prevalence of SBIs ipsilateral to ICA disease (33%) compared with the contralateral side (20.8%; P=0.0067). There was no significant difference in the prevalence of lacunar SBIs (including both white and deep gray matter) between hemispheres (P=0.109), but there was a significantly higher prevalence of cortical SBIs occurring downstream from ICA disease (P=0.0045). High inter-rater reliability was observed (κ=0.818).

CONCLUSIONS

Patients with asymptomatic ICA disease demonstrate a higher prevalence of SBI downstream from their ICA atherosclerotic disease compared with the contralateral side but only of the cortical and not lacunar SBI subtype.

Relationship between metabolic and vascular conditions and cognitive decline among older Mexican Americans

OBJECTIVE

Metabolic and vascular conditions have been independently associated with dementia and cognitive decline among older adults, but research on the combined effects that these conditions have on cognitive decline, especially among older Mexican Americans, is lacking. The purpose of this study was to examine the relationship between metabolic and vascular conditions and cognitive decline among older Mexican Americans.

METHODS

The final sample included 2767 participants of the Hispanic Established Populations for the Epidemiologic Study of the Elderly. Linear mixed-effects regression was used to model cognitive decline across six examinations (1993-2007) according to the number (zero, one, two, and three to four) of metabolic and vascular conditions (hypertension, diabetes, stroke, and heart attack).

RESULTS

Of the 2767 participants included in the final sample, 777 had zero conditions, 1314 had one condition, 553 had two conditions, and 123 had three to four conditions. Participants with two or three to four conditions had significantly greater cognitive decline compared with participants with zero or one condition. Stroke had the largest effect size on cognitive decline based on the proportion of variance that stroke accounted for in the linear mixed-effects model.

CONCLUSION

Mexican American older adults with multiple metabolic and vascular conditions exhibit greater cognitive decline than those with zero or one condition. Public health interventions designed to reduce the prevalence of chronic metabolic and vascular conditions, in particular stroke, may limit the severity of cognitive decline among older Mexican Americans.

Polyamines and their metabolites as diagnostic markers of human diseases

Polyamines, putrescine, spermidine and spermine, are ubiquitous in living cells and are essential for eukaryotic cell growth. These polycations interact with negatively charged molecules such as DNA, RNA, acidic proteins and phospholipids and modulate various cellular functions including macromolecular synthesis. Dysregulation of the polyamine pathway leads to pathological conditions including cancer, inflammation, stroke, renal failure and diabetes. Increase in polyamines and polyamine synthesis enzymes is often associated with tumor growth, and urinary and plasma contents of polyamines and their metabolites have been investigated as diagnostic markers for cancers. Of these, diacetylated derivatives of spermidine and spermine are elevated in the urine of cancer patients and present potential markers for early detection. Enhanced catabolism of cellular polyamines by polyamine oxidases (PAO), spermine oxidase (SMO) or acetylpolyamine oxidase (AcPAO), increases cellular oxidative stress and generates hydrogen peroxide and a reactive toxic metabolite, acrolein, which covalently incorporates into lysine residues of cellular proteins. Levels of protein-conjuagated acrolein (PC-Acro) and polyamine oxidizing enzymes were increased in the locus of brain infarction and in plasma in a mouse model of stroke and also in the plasma of stroke patients. When the combined measurements of PC-Acro, interleukin 6 (IL-6), and C-reactive protein (CRP) were evaluated, even silent brain infarction (SBI) was detected with high sensitivity and specificity. Considering that there are no reliable biochemical markers for early stage of stroke, PC-Acro and PAOs present promising markers. Thus the polyamine metabolites in plasma or urine provide useful tools in early diagnosis of cancer and stroke.

Association of blood lactate with carotid atherosclerosis: the Atherosclerosis Risk in Communities (ARIC) Carotid MRI Study

OBJECTIVES

Cardiovascular risk factors such as aging, smoking, and insulin resistance may lead to atherosclerosis through various mechanisms of which their association with mitochondrial dysfunction may be one of them. In order to examine this hypothesis, we assessed the association between elevated blood lactate, a marker of mitochondrial dysfunction, and carotid atherosclerosis.

METHODS

From a total of 2066 participants from the Atherosclerosis Risk In Communities Carotid MRI study, 1496 were included for this analysis. Wall Thickness and Lipid core presence were measured using gadolinium-enhanced MRI. Blood lactate was categorized into quartiles (Q1: <5.9 mg/dl, Q2: 5.9-7.2 mg/dl, Q3: 7.3-9.2 mg/dl, and Q4: >9.2 mg/dl).

RESULTS

Of the 1496 study participants, 763 (51%) were females, 296 (19.8%) African American, 539 (36%) obese and 308 (20.6%) had diabetes. There was a strong and graded association between lactate and wall thickness [Q1: 1.08 mm (95% CI: 1.01 mm-1.15 mm), Q2: 1.33 mm (95% CI: 1.19 mm-1.47 mm), Q3: 1.44 (95% CI: 1.34 mm-1.54 mm) and Q4: 1.62 (95% CI: 1.53 mm-1.71 mm); p for trend <0.001] after adjusting for age, gender, ethnicity, stature, body mass index (BMI), waist circumference, LDL, High sensitivity C reactive protein (HsCRP), statin use, thiazolidinedione use, hypertension, and diabetes. This association was attenuated, but still significant, after adjusting for a marker of insulin resistance, the triglyceride/HDL ratio, [Q1: 0.96 mm (95% CI: 0.82 mm-1.10 mm), Q2: 1.17 mm (95% CI: 1.08 mm-1.26 mm), Q3: 1.18 mm (95% CI: 1.07 mm-1.29 mm), Q4: 1.22 mm (95% CI: 1.13 mm-1.31 mm), p for linear trend 0.039]. There was no association of lactate with lipid core presence after adjustment for wall thickness.

CONCLUSIONS

Blood lactate is associated with carotid atherosclerosis. Attenuation of the association with adjustment for triglyceride/HDL ratio, a marker of insulin resistance, suggests that lactate's association with carotid atherosclerosis may be related to insulin resistance.

Large-vessel correlates of cerebral small-vessel disease

OBJECTIVE

Our aim was to investigate the relationship of carotid structure and function with MRI markers of cerebral ischemic small-vessel disease.

METHODS

The study comprised 1,800 participants (aged 72.5 ± 4.1 years, 59.4% women) from the 3C-Dijon Study, a population-based, prospective cohort study, who had undergone quantitative brain MRI and carotid ultrasound. We used multivariable logistic and linear regression adjusted for age, sex, and vascular risk factors.

RESULTS

Presence of carotid plaque and increasing carotid lumen diameter (but not common carotid artery intima-media thickness) were associated with higher prevalence of lacunar infarcts: odds ratio (OR) = 1.60 (95% confidence interval [CI]: 1.09-2.35), p = 0.02 and OR = 1.24 (95% CI: 1.02-1.50), p = 0.03 (by SD increase). Carotid plaque was also associated with large white matter hyperintensity volume (WMHV) (age-specific top quartile of WMHV distribution): OR = 1.32 (95% CI: 1.04-1.67), p = 0.02, independently of vascular risk factors. Increasing Young elastic modulus and higher circumferential wall stress, reflecting augmented carotid stiffness, were associated with increasing WMHV (effect estimate [β] ± standard error: 0.0003 ± 0.0001, p = 0.024; β ± standard error: 0.005 ± 0.002, p = 0.008). Large WMHV was also associated with increasing Young elastic modulus (OR = 1.22 [95% CI: 1.04-1.42], p = 0.01) and with decreasing distensibility coefficient (OR = 0.83 [95% CI: 0.69-0.99], p = 0.04), independently of vascular risk factors. Associations of carotid lumen diameter with lacunar infarcts and of carotid stiffness markers with WMHV were independent of carotid plaque.

CONCLUSIONS

In addition to and independently of carotid plaque, increasing carotid lumen diameter and markers of carotid stiffness were associated with increasing prevalence of lacunar infarcts and increasing WMHV, respectively.

Silent Brain Infarction – A Review of Recent Observations

Silent brain infarction is a cerebral ischaemic event evident on brain imaging without any clinical symptom. Silent brain infarction is often detected in apparently healthy, elderly people and in different selected patient groups as well. Lately, several studies were carried out in order to identify the clinical conditions leading to silent brain infarction. A large number of clinical and paraclinical parameters were found to increase silent brain infarction prevalence, and the continuously growing list of risk factors revealed that the majority of them are similar to those related to stroke. Accordingly, some consider silent brain infarction the preclinical stage of clinically overt stroke. This point of view emphasizes the early recognition and management of silent brain infarction-related risk factors, and a great need for comparative studies, which could elicit the most sensitive indicators of the increased silent brain infarction risk, especially the ones that could be cost-effectively screened in the large populations as well.

Silent cerebral events in asymptomatic carotid stenosis

BACKGROUND

Approximately 20% of strokes are attributable to carotid stenosis. However, the number of asymptomatic patients needed to prevent one stroke or death with endarterectomy is high at 17 to 32. There is a clear need to identify asymptomatic individuals at high risk of developing future ischemic events to improve the cost-effectiveness of surgery. Our aim was to examine the evidence for subclinical microembolization and silent brain infarction in the prediction of stroke in asymptomatic carotid stenosis using transcranial Doppler (TCD), computed tomography (CT), and magnetic resonance imaging (MRI).

METHODS

The review was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Articles regarding humans between 1966 and 2010 were identified through systematic searches of Pubmed, MEDLINE, and EMBASE electronic databases using a predetermined search algorithm.

RESULTS

Fifty-eight full text articles met the inclusion criteria. A median of 28% of microemboli positive patients experienced a stroke or transient ischemic attack during follow-up compared with 2% of microemboli negative patients (P = .001). The same was true for the end point of stroke alone with a median of 10% of microemboli positive patients experiencing a stroke vs 1% of microemboli negative patients (P = .004). A specific pattern of silent CT infarctions was related to future stroke risk (odds ratio [OR] = 4.6; confidence interval [CI] = 3.0-7.2; P < .0001). There are no prospective MRI studies linking silent infarction and stroke risk.

CONCLUSIONS

There is level 1 evidence for the use of TCD to detect microembolization as a risk stratification tool. However, this technique requires further investigation as a stroke prevention tool and would be complemented by improvements in carotid plaque imaging.

Protein-conjugated acrolein as a biochemical marker of brain infarction

The relationship between acrolein (CH(2) =CH-CHO) and brain infarction is the focus of this review. It has been found that acrolein is produced mainly within cells from polyamines by polyamine oxidases (PAOs), especially from spermine by spermine oxidase during cell damage, and that acrolein is more toxic than reactive oxygen species (ROS) in a cell culture system. Thus, the possibility that acrolein and PAOs are good biochemical markers of stroke was tested because there are no other reliable biochemical markers at the early stage of stroke. Levels of protein-conjugated acrolein (PC-Acro) and PAOs (acrolein-producing enzymes) were significantly increased in the plasma of stroke patients. The multiplied value of PC-Acro by PAOs was nearly parallel with the size of stroke. Furthermore, when the combined measurements of PC-Acro, interleukin-6 (IL-6) and C-reactive protein (CRP) were evaluated along with age using a receiver operating characteristic (ROC) curve, even silent brain infarction (SBI), which is a small brain infarction, was indicated with approximately 84% sensitivity and specificity. These findings clearly indicate that acrolein is strongly correlated with cell damage during brain infarction.

Relationship between carotid atherosclerosis and cerebral infarction

OBJECTIVE

To study the relationship between carotid atherosclerosis and cerebral infarction (CI).

METHODS

Between November 2008 and March 2009, 147 CI patients (CI group) and 48 patients with non-cerebrovascular diseases (control group) were enrolled from inpatients of Neurology Department of our hospital. The diagnostic criterion of thickened carotid intima was set as 1.0 mm<intima-media thickness (IMT) < 1.5 mm and that of carotid plaque was as IMT 1.5 mm. Carotid atherosclerosis was divided into three levels: normal intima, thickened intima, and plaque formation. The color Doppler ultrasonography data of carotid arteries in all patients were analyzed and the severity of carotid atherosclerosis was compared between the two groups.

RESULTS

In the CI group, 36 (24.5%) patients had normal carotid intima, 22 (15.0%) had thickened carotid intima, and 89 (60.5%) had carotid plaque. In the control group, 22 (45.8%) patients had normal carotid intima, 4 (8.3%) had thickened carotid intima, and 22 (45.8%) had carotid plaque. The severity of carotid atherosclerosis in the CI group was higher than that in the control group (P = 0.022). There was significant difference in the constitution of carotid plaque between the two groups (P = 0.001); the CI group mainly had the soft plaque (55/89, 61.8%), whereas the control group mainly had the hard plaque (17/22, 77.3%). The first three common locations of carotid plaque in both groups were carotid bifurcation (CI group: 73.7%; control group: 64.1%), common carotid artery (CI group: 20.4%; control group: 25.6%), and internal carotid artery (CI group: 5.9%; control group: 10.3%). The location of carotid plaque between the two groups was not significantly different (P = 0.438). There was no difference in the carotid inner diameter or resistance index between the two groups (P > 0.05).

CONCLUSIONS

Carotid atherosclerosis is to some extent able to reveal the atherosclerotic condition of cerebral arteries and act as an important predictor for the risk of CI. The color Doppler ultrasonography of carotid arteries can provide a convenient way for the prevention and treatment of CI.

Correlation between images of silent brain infarction, carotid atherosclerosis and white matter hyperintensity, and plasma levels of acrolein, IL-6 and CRP

OBJECTIVE

We found previously that the measurement of plasma levels of protein-conjugated acrolein (PC-Acro) together with IL-6 and CRP can be used to identify silent brain infarction (SBI) with high sensitivity and specificity. The aim of this study was to clarify how three biochemical markers are correlated to SBI, carotid atherosclerosis (CA) and white matter hyperintensity (WMH).

METHODS

The levels of PC-Acro, IL-6 and CRP in plasma were measured by ELISA. SBI and WMH were evaluated by MRI, and CA was evaluated by duplex carotid ultrasonography.

RESULTS

A total of 790 apparently healthy volunteers were classified into 260 control, 214 SBI, 263 CA and 245 WMH subjects, which included 187 subjects with two or three pathologies. When the combined measurements of PC-Acro, IL-6 and CRP were evaluated together with age, using a receiver operating characteristic curve and artificial neural networks, the relative risk value (RRV), an indicator of tissue damage, was in the order SBI with CA (0.90)>SBI (0.80)>CA (0.76)>WMH with CA (0.65)>WMH (0.46)>control (0.14). RRV was also correlated with severity in each group of SBI, CA and WMH.

CONCLUSION

The RRV supports the idea that the degree of risk to develop a stroke is in the order SBI>CA>WMH.

Intima-media thickness and regional cerebral blood flow in older adults

BACKGROUND AND PURPOSE

The relationship between the thickness of the carotid intima (IMT) and brain function remains unclear in those without clinical manifestations of cerebrovascular disease. Understanding the neural correlates of this vascular measure is important in view of emerging evidence linking poorer cognitive performance with increased IMT in individuals without clinical cerebrovascular disease.

METHODS

Seventy-three participants in the Baltimore Longitudinal Study of Aging (70.9 years; SD, 7.3) were evaluated with carotid artery ultrasound and resting [(15)O]H(2)O positron emission tomography.

RESULTS

After adjusting for age, gender, and gray and white matter volumes in the regions where IMT is related to regional cerebral blood flow (rCBF), we found that higher IMT was associated with lower rCBF in lingual, inferior occipital, and superior temporal regions. Higher IMT was also associated with higher rCBF in medial frontal gyrus, putamen, and hippocampal-uncal regions (P=0.001). Whereas women had lower IMT (P=0.01) and mean arterial pressure (P=0.05) than men, they showed more robust associations between IMT and rCBF. The relationship between IMT and rCBF was only minimally affected by additional adjustment for mean arterial pressure.

CONCLUSIONS

IMT is related to patterns of resting rCBF in older adults without clinical manifestations of cerebrovascular disease, suggesting that there are regional differences in CBF that are associated with subclinical vascular disease.

Associations of brachial-ankle pulse wave velocity and carotid atherosclerotic lesions with silent cerebral lesions

Silent cerebral lesions are increasingly found in mass screenings using MRI and magnetic resonance angiography (MRA). The purpose of this paper is to assess the usefulness of two non-invasive clinical tests-carotid ultrasound examination and brachial-ankle pulse wave velocity (baPWV) measurement-for predicting silent cerebral infarction (SCI) and silent intracranial arterial stenosis. Data were collected on 480 asymptomatic adult subjects who participated in a brain screening program at a single hospital between April 2003 and March 2006. All participants underwent baPWV measurement, B-mode ultrasonography of carotid arteries, MRI, and MRA. Data on 476 (99.1%) subjects were included in the analysis. Among these, 273 (57.4%) were male and the mean age was 51.5 years; 161 (33.8%) had carotid plaque; 33 (6.9%) had increased intima-media thickness (IMT); 99 (20.8%) had SCI; and 7 (1.5%) had intracranial arterial stenosis. The multivariate analysis showed that age (odds ratio [OR]: 1.12; 95% confidence interval [CI]: 1.08-1.17), carotid plaque (OR: 2.69; 1.59-4.56), increased IMT (OR: 2.40; 1.02-5.65), and a history of hypertension treatment (OR 2.22; 1.11-4.43) were significantly associated with SCI. Also, increased IMT (OR 9.70: 1.48-63.71) was related to intracranial arterial stenosis. Brachial-ankle PWV was related to SCI (p<0.01) and intracranial stenosis (p=0.01) in univariate analysis but not in multivariate analysis. The presence of carotid plaque and that of increased IMT on ultrasound examination are useful for assessing the risk of SIC. Increased IMT is also predictive of intracranial arterial stenosis.