The epidemiology of silent brain infarction: a systematic review of population-based cohorts

The risk factors of old silent brain infarctions in carotid artery stenosis

BACKGROUND AND PURPOSE

This study aims to investigate the risk factors of old ipsilateral silent brain infarctions (iSBIs) in patients with internal carotid artery (ICA) stenosis.

METHODS

Consecutive patients with unilateral ICA stenosis ≥ 50% or occlusion were retrospectively enrolled. Old iSBIs were assessed on magnetic resonance imaging. Baseline characteristics and imaging features were compared between patients with and without iSBIs. Multivariable regression analysis was conducted to identify independent risk factors of iSBIs.

RESULTS

We enrolled 274 patients with unilateral ICA stenosis ≥ 50% or occlusion. One hundred thirty-three patients had iSBIs to stenosed ICA (48.54%). One hundred thirty-seven patients had recent brain infarction on either side (50.0%). The patients with iSBIs had a lower level of high-density lipoprotein [OR 0.60, 95% CI (0.36-0.96), P = 0.045], higher prevalence of irregular/ulcer plaque [OR 10.71, 95% CI (4.60-24.95), P < 0.0001], and incompleteness of circle of Willis [OR 0.27, 95% CI (0.16-0.45), P < 0.0001] in all enrolled patients. In the patients without recent infarction on either side, lower level of high-density lipoprotein [OR 0.42, 95% CI (0.27-0.88), P = 0.031], higher prevalence of irregular/ulcer plaque [OR 12.73, 95% CI (4.13-39.22), P < 0.0001] and incompleteness of circle of Willis [OR 0.24, 95% CI (0.11-0.50), P = 0.004] were independently associated with iSBIs. The results were similar in ICA stenosis patients with recent brain infarction on either side.

CONCLUSION

In patients with carotid stenosis, incompleteness of circle of Willis, irregular/ulcer plaque, and lower level of high-density lipoprotein were independently associated with old iSBIs.

The high prevalence of abnormal MRI findings in non-neuropsychiatric patients with persistently positive antiphospholipid antibodies

OBJECTIVES

Thrombosis occurring in the central nerve system is common in antiphospholipid syndrome (APS) patients, leading to neuropsychiatric symptoms. We investigated the prevalence of silent brain abnormalities on magnetic resonance imaging (MRI) in primary antiphospholipid syndrome (PAPS) patients and antiphospholipid antibodies (aPL) carriers and assessed the association between the vascular risk factors, aPL profile, clinical manifestations, and MRI abnormalities.

METHODS

We consecutively included 44 PAPS patients, 24 aPL carriers and 23 healthy controls with comparable age and gender in a single-center, observational cross-sectional study. None of the patients had a history of stroke, TIA, migraine, dementia, epilepsy and bipolar disorders. On cerebral MRI, we assessed the imaging features and location of abnormality. Multivariate analysis was performed to identify the risk factors contributing to the MRI abnormalities.

RESULTS

38 (55.88%) patients persisted abnormal MRI findings, while only one healthy control showed some abnormalities in the MR findings. Lacunes were the most frequent MRI abnormality in aPL (+) group (31/68, 45.59%), which were followed by white matter hyperintensities (20/68, 29.41%). In all study population, age (OR = 1.086, p= 0.016) and LA positivity (OR = 5.191, p= 0.002) were the independent associated factors with the brain MRI abnormalities. When analyzed only in the aPL (+) group, age (OR = 1.116, p= 0.007), female gender (OR = 7.519, p= 0.025) and thrombocytopenia (OR = 8.336, p= 0.047) were the significant independent risk factors with abnormal MRI.

CONCLUSIONS

PAPS patients and aPL carriers showed a high prevalence of brain MRI abnormalities, indicating an increased cerebrovascular risk, which emphasized attention to silent cerebral lesions in persistently aPL positive patients.

[The effect of long-term beta-blockers on melatonin secretion, sleep quality, and vascular brain damage]

Circadian rhythm of pineal melatonin production is paced by the thalamus suprachiasmatic nucleus (SCN) depending on the lighting conditions via signal transduction to pinealocytes beta-receptors. Melatonin is a natural regulator of many physiological processes, and the decrease of its synthesis leads to various diseases, in particular, insomnia and metabolic disorders. It is known that administration of beta-blockers reduces melatonin production, but the data showing clinical significance of melatonin reduction associated with beta-blockers administration are still contradictory.

OBJECTIVE

The influence of long-term administration of beta-blockers to melatonin synthesis, sleep quality and vascular brain damage.

MATERIALS AND METHODS

The main study group included 114 patients, aged 47-83, with cardiovascular diseases, who were under a complex therapy with long-term administration of beta-blockers. The comparison group included 110 patients with cardiovascular diseases, similar in age and sex, who did not receive beta-blockers in their complex therapy. The circadian dynamics of melatonin synthesis was observed by excretion of 6-sulfatoxymelatonin (6-SM), the major metabolite of melatonin, in three urinary samples (day, evening, night). All the patients underwent night polysomnography to assess the severity of sleep disorders. The severity of vascular brain damage was assessed using magnetic resonance imaging.

RESULTS

The analyses showed large variability in individual values of 6-SM circadian excretion of patients with cardiovascular diseases (from 0.9 to 133 μg/24h with a mid-point 16.8 μg/24h). A considerable decrease of 6-SM circadian excretion is detected in the group of patients taking beta-blockers comparing to those not Me [q 25; q 75]: 12.8 [6.2; 21.1] and 24.0 [12.5; 41.5] μg/24h, respectively (p<0.001), with no differences in sleep values and severity of vascular brain damage. Comparing subgroups of patients with 6-SM circadian excretion lower and higher than 16.8 μg/24h showed a significant increase of sleep latency, decrease of rapid eye movement sleep (REM sleep), increasing number of gliosis foci in white matter of the brain with higher values of leptin, leptin/adiponectin ratio and glycohemoglobin in the group of patients with 6-SM circadian excretion ≤16.8 μg/24h.

CONCLUSION

A low level of endogenous melatonin is a risk factor for development of sleep structure and quality disorders, vascular white matter brain damages with a higher risk for metabolic disorders. Long-term beta-blockers administration decrease endogenous melatonin synthesis to 50% increasing the risk for insomnia and vascular brain damage, mostly in patients with lower initial level of 6-SM circadian excretion.: melatonin, 6-sulfatoxymelatonin, beta-blockers, insomnia, vascular white matter brain damage, leptin, adiponectin.

MRI of healthy brain aging: A review

We present a review of the characterization of healthy brain aging using MRI with an emphasis on morphology, lesions, and quantitative MR parameters. A scope review found 6612 articles encompassing the keywords "Brain Aging" and "Magnetic Resonance"; papers involving functional MRI or not involving imaging of healthy human brain aging were discarded, leaving 2246 articles. We first consider some of the biogerontological mechanisms of aging, and the consequences of aging in terms of cognition and onset of disease. Morphological changes with aging are reviewed for the whole brain, cerebral cortex, white matter, subcortical gray matter, and other individual structures. In general, volume and cortical thickness decline with age, beginning in mid-life. Prevalent silent lesions such as white matter hyperintensities, microbleeds, and lacunar infarcts are also observed with increasing frequency. The literature regarding quantitative MR parameter changes includes T₁ , T₂ , T₂ *, magnetic susceptibility, spectroscopy, magnetization transfer, diffusion, and blood flow. We summarize the findings on how each of these parameters varies with aging. Finally, we examine how the aforementioned techniques have been used for age prediction. While relatively large in scope, we present a comprehensive review that should provide the reader with sound understanding of what MRI has been able to tell us about how the healthy brain ages.

Association of Silent Cerebrovascular Disease Identified Using Natural Language Processing and Future Ischemic Stroke

BACKGROUND AND OBJECTIVE

Silent cerebrovascular disease (SCD), comprised of silent brain infarction (SBI) and white matter disease (WMD), is commonly found incidentally on neuroimaging scans obtained in routine clinical care. However, their prognostic significance is not known. We aimed to estimate the incidence of, and risk increase in, future stroke in patients with incidentally-discovered SCD. METHODS: Patients in Kaiser Permanente Southern California (KPSC) health system aged ≥ 50, without prior ischemic stroke, transient ischemic attack, or dementia/Alzheimer's disease receiving a head CT or MRI between 2009-2019 were included. SBI and WMD were identified by natural language processing (NLP) from the neuroimage report.

RESULTS

Among 262,875 individuals receiving neuroimaging, NLP identified 13,154 (5.0%) with SBI and 78,330 (29.8%) with WMD. The incidence of future stroke was 32.5 (95% CI 31.1, 33·9) per 1,000 patient-years for patients with SBI; 1.·3 (95% CI 18.9, 19.8) for patients with WMD and 6.8 (95% CI 6.7, 7.0) for patients without SCD. The crude HR associated with SBI was 3.40 (95% CI 3.25 to 3.56); and for WMD was 2.63 (95% CI 2.54 to 2·71). With MRI-discovered SBI, the adjusted HR was 2.95 (95% CI 2.53 to 3.44) for those < age 65 and 2.15 (95% CI 1.91 to 2.41) for those ≥ age 65. With CT scan, the adjusted HR was 2.48 (95% CI 2.19 to 2.81) for those < age 65 and 1.81 (95% CI 1.71 to 1.91) for those >= age 65. The adjusted HR associated with a finding of WMD was 1.76 (95% CI 1.69 to 1.82) and was not modified by age or imaging modality.

DISCUSSION

Incidentally-discovered SBI and WMD are common and associated with increased risk of subsequent symptomatic stroke representing an important opportunity for stroke prevention.

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.

Deep Cerebral Perforators: Anatomical Distribution and Clinical Symptoms: An Overview

The anatomic distribution of the deep cerebral perforators is considered either a given or subject to enormous variability. Most published overviews on this topic only report findings from a limited number of anatomic dissections, and no attempt has been made to date to provide a comprehensive overview of all published data. A comprehensive literature search was performed on MEDLINE, Embase, and Google Scholar with the help of an information specialist. Three types of studies were included: (1) articles that described the anatomy and distribution territories of perforator groups arising from the arteries of the circle of Willis; (2) studies that evaluated the anatomy of the deep cerebral perforators using imaging techniques; and (3) studies that evaluated either microsurgically or radiologically confirmed perforator occlusion and reported the (magnetic resonance imaging-confirmed) distribution territory of the infarction together with a description of the clinical symptoms associated as a result of the infarction. A total of 2715 articles were screened and 53 were included. Of these, 40 dealt with the anatomic and imaging anatomy of perforator groups (37 reported results of dissections and 3 results of imaging studies), with a total of 2421 hemispheres investigated. Another 13 articles with 680 patients were included that evaluated perforator infarction territories. The deep cerebral perforator distribution shows large variability with poor concordance rates among reported studies, with the exception of the posterior communicating and anterior choroidal artery perforators. Despite the assumption that cerebral perforator anatomy is a given, studies show large variability in the anatomic distribution of various perforator groups. Perforator anatomy and relationships between perforator groups, as well as potential collateral circulation in these territories should be prioritized as a research topic in cerebrovascular disease in the near future.

Association of Ischemic Imaging Phenotype With Progression of Brain Atrophy and Cerebrovascular Lesions on MRI: The SMART-MR Study

OBJECTIVE

To investigate the association of silent vascular lesions, imaging negative ischemia, and symptomatic cerebrovascular disease with long-term progression of brain atrophy and cerebrovascular lesions in patients with arterial disease.

METHODS

Within the SMART-MR study, stroke status of participants at baseline was classified as no cerebrovascular disease (reference group, n=829), symptomatic cerebrovascular disease (n=206), silent vascular lesion (n=157), and imaging negative ischemia (n=90) based upon clinical and MRI findings. Using linear mixed models, changes in brain and white matter hyperintensity (WMH) volumes at baseline and during 12 years of follow-up were studied in stroke classifications. Relative risks were estimated for new infarcts during follow-up associated with stroke classifications. Analyses were adjusted for age, sex, cardiovascular risk factors, and medications.

RESULTS

Symptomatic cerebrovascular disease associated with 0.35 SDs (95%CI 0.24-0.47) smaller brain volume and 0.61 SDs (95%CI 0.48-0.74) larger WMH volume at baseline, and increased risk for new infarcts during follow-up (risk ratio (RR) 2.89; 95%CI 2.00-4.16). Silent vascular lesions associated with 0.15 SDs (95%CI 0.01-0.88) smaller brain volume, 0.02 SDs (95%CI 0.01-0.03) steeper brain atrophy slope, and 0.48 SDs (95%CI 0.32-0.64) larger WMH volume at baseline, in addition to increased risk for lacunes (RR 2.08; 95%CI 1.48-2.94). Individuals with imaging negative ischemia had increased risk for cortical infarcts (RR=2.88; 95%CI 2.17-3.82).

CONCLUSIONS

Patients with symptomatic cerebrovascular disease, silent vascular lesions, or imaging negative ischemia have different course of brain volume loss and cerebrovascular lesions development. These findings may have implications for future stroke risk and dementia and need further investigation.

Modularity and robustness of frontal cortical networks

Neural activity underlying short-term memory is maintained by interconnected networks of brain regions. It remains unknown how brain regions interact to maintain persistent activity while exhibiting robustness to corrupt information in parts of the network. We simultaneously measured activity in large neuronal populations across mouse frontal hemispheres to probe interactions between brain regions. Activity across hemispheres was coordinated to maintain coherent short-term memory. Across mice, we uncovered individual variability in the organization of frontal cortical networks. A modular organization was required for the robustness of persistent activity to perturbations: each hemisphere retained persistent activity during perturbations of the other hemisphere, thus preventing local perturbations from spreading. A dynamic gating mechanism allowed hemispheres to coordinate coherent information while gating out corrupt information. Our results show that robust short-term memory is mediated by redundant modular representations across brain regions. Redundant modular representations naturally emerge in neural network models that learned robust dynamics.

Cardiovascular risk scoring and magnetic resonance imaging detected subclinical cerebrovascular disease

Aims 

Cardiovascular risk factors are used for risk stratification in primary prevention. We sought to determine if simple cardiac risk scores are associated with magnetic resonance imaging (MRI)-detected subclinical cerebrovascular disease including carotid wall volume (CWV), carotid intraplaque haemorrhage (IPH), and silent brain infarction (SBI).

Methods and results

A total of 7594 adults with no history of cardiovascular disease (CVD) underwent risk factor assessment and a non-contrast enhanced MRI of the carotid arteries and brain using a standardized protocol in a population-based cohort recruited between 2014 and 2018. The non-lab-based INTERHEART risk score (IHRS) was calculated in all participants; the Framingham Risk Score was calculated in a subset who provided blood samples (n = 3889). The association between these risk scores and MRI measures of CWV, carotid IPH, and SBI was determined. The mean age of the cohort was 58 (8.9) years, 55% were women. Each 5-point increase (∼1 SD) in the IHRS was associated with a 9 mm³ increase in CWV, adjusted for sex (P < 0.0001), a 23% increase in IPH [95% confidence interval (CI) 9–38%], and a 32% (95% CI 20–45%) increase in SBI. These associations were consistent for lacunar and non-lacunar brain infarction. The Framingham Risk Score was also significantly associated with CWV, IPH, and SBI. CWV was additive and independent to the risk scores in its association with IPH and SBI.

Conclusion 

Simple cardiovascular risk scores are significantly associated with the presence of MRI-detected subclinical cerebrovascular disease, including CWV, IPH, and SBI in an adult population without known clinical CVD.

Relationship between Retinal Microvasculature, Cardiovascular Risk and Silent Brain Infarction in Hypertensive Patients

Objective: The aims of this study are to analyze the role of artery-vein ratio AVR assessment using VesselMap 2 software (Imedos Systems) and cardiovascular risk evaluation by means of REGICOR in the prediction of silent brain infarction (SBI) in middle-age hypertensive patients from the ISSYS study. Material and Methods: A cross-sectional study with 695 patients with hypertension aged 50 to 70 years who participated in the project Investigating Silent Strokes in HYpertensives: a Magnetic Resonance Imaging Study (ISSYS), was conducted in two Primary Care Centres of Barcelona. Participants agreed to a retinography and an MRI to detect silent brain infarction (SBI). The IMEDOS software was used for the semiautomatic caliber measurement of retinal arteries and veins, and the AVR was considered abnormal when <0.66. The REGICOR score was calculated for all patients. Results: Multivariate logistic regression analysis was used to evaluate the impact of AVR and REGICOR scores on SBI. The OR (odds ratio) for a high REGICOR score and an abnormal AVR were 3.16 and 4.45, respectively. When analysing the interaction of both factors, the OR of an abnormal AVR and moderate REGICOR score was 3.27, whereas with a high REGICOR score it reached 13.07. Conclusions: The measurement of AVR in patients with hypertension and with a high REGICOR score can contribute to the detection of silent brain infarction.

Effect of methylenetetrahydrofolate reductase gene polymorphisms and oxidative stress in silent brain infarction

Ischemic infarctions occur under the influence of genetic and environmental factors. In our study, the role of ischemia-modified albumin and thiol balance, which are new markers in determining oxidative damage together with MTHFR gene polymorphisms and homocysteine levels, in the development of SBI was investigated. White matter lesions in the magnetic resonance imaging (MRI) results of the patients were evaluated according to the Fazekas scale and divided into groups (Grade 0, 1, 2, and 3). Homocysteine, folate, B12, IMA, total thiol, and native thiol were measured by biochemical methods. The polymorphisms in MTHFR genes were investigated by the RT-PCR method. According to our results, a significant difference was found between the groups in age, homocysteine, folate, IMA, total thiol, and native thiol parameters (p < 0.05). When we compared the groups in terms of genotypes of the C677T gene, we found a significant difference in TT genotype between grades 0/3 and 1/3 (p < 0.05). We determined that homocysteine and IMA levels increased and folate levels decreased in CC/TT and CT/TT genotypes in the C677T gene (p < 0.05). Considering our results, the observation of homocysteine and IMA changes at the genotype level of the MTHFR C677T gene and between the groups, and the deterioration of thiol balance between the groups suggested that these markers can be used in the diagnosis of silent brain infarction.

Agreement between neuroimages and reports for natural language processing-based detection of silent brain infarcts and white matter disease

BACKGROUND

There are numerous barriers to identifying patients with silent brain infarcts (SBIs) and white matter disease (WMD) in routine clinical care. A natural language processing (NLP) algorithm may identify patients from neuroimaging reports, but it is unclear if these reports contain reliable information on these findings.

METHODS

Four radiology residents reviewed 1000 neuroimaging reports (RI) of patients age > 50 years without clinical histories of stroke, TIA, or dementia for the presence, acuity, and location of SBIs, and the presence and severity of WMD. Four neuroradiologists directly reviewed a subsample of 182 images (DR). An NLP algorithm was developed to identify findings in reports. We assessed interrater reliability for DR and RI, and agreement between these two and with NLP.

RESULTS

For DR, interrater reliability was moderate for the presence of SBIs (k = 0.58, 95 % CI 0.46-0.69) and WMD (k = 0.49, 95 % CI 0.35-0.63), and moderate to substantial for characteristics of SBI and WMD. Agreement between DR and RI was substantial for the presence of SBIs and WMD, and fair to substantial for characteristics of SBIs and WMD. Agreement between NLP and DR was substantial for the presence of SBIs (k = 0.64, 95 % CI 0.53-0.76) and moderate (k = 0.52, 95 % CI 0.39-0.65) for the presence of WMD.

CONCLUSIONS

Neuroimaging reports in routine care capture the presence of SBIs and WMD. An NLP can identify these findings (comparable to direct imaging review) and can likely be used for cohort identification.

Association between Ambient Air Pollution and MRI-Defined Brain Infarcts in Health Examinations in China

The study aimed to evaluate the relationships between air pollutants and risk of magnetic resonance imaging (MRI)-defined brain infarcts (BI). We used data from routine health examinations of 1,400,503 participants aged ≥18 years who underwent brain MRI scans in 174 cities in 30 provinces in China in 2018. We assessed exposures to particulate matter (PM)_2.5, PM₁₀, nitrogen dioxide (NO₂), and carbon monoxide (CO) from 2015 to 2017. MRI-defined BI was defined as lesions ≥3 mm in diameter. Air pollutants were associated with a higher risk of MRI-defined BI. The odds ratio (OR) (95% CI) for MRI-defined BI comparing the highest with the lowest tertiles of air pollutant concentrations was 2.00 (1.96–2.03) for PM_2.5, 1.68 (1.65–1.71) for PM₁₀, 1.58 (1.55–1.61) for NO₂, and 1.57 (1.54–1.60) for CO. Each SD increase in air pollutants was associated with 16–42% increases in the risk of MRI-defined BI. The associations were stronger in the elderly subgroup. This is the largest survey to evaluate the association between air pollution and MRI-defined BI. Our findings indicate that ambient air pollution was significantly associated with a higher risk of MRI-defined BI.

Incidence and Risk Factors for Silent Brain Infarction After On-Pump Cardiac Surgery: A Meta-analysis and Meta-regression of 29 Prospective Cohort Studies

BACKGROUND

Silent brain infarction (SBI) happens at a considerable rate after on-pump cardiac surgery. Though termed silent, SBI is related to unfavorable clinical outcomes including higher incidence of future stroke and neurocognitive impairment in the general population. The risk factors of SBI have not been fully identified in both individual studies and several meta-analyses addressing the topic. In this meta-analysis, we aimed to conduct meta-regression analysis for the first time to explore risk factors for SBI after on-pump cardiac surgery.

METHODS

This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Medline, Embase, Central, Web of Science, and Wiley databases were searched for relevant studies. Preoperative patient baseline characteristics and intraoperative surgical parameters were extracted from included studies. For meta-regression, a P value of less than 0.1 was considered statistically significant in both univariable and multivariable analyses.

RESULTS

Twenty-nine studies with 1478 patients were included in this meta-analysis. The summarized SBI rate after on-pump cardiac surgery was 37% (95% CI 0.27-0.47, P < 0.0001). Heterogeneity between studies was significant (I2 = 94.9%, P < 0.0001). In multivariable meta-regression, we found that age (coefficient 0.014, 95% CI 0.001-0.029, P = 0.043), diabetes (coefficient 0.006, 95% CI - 0.001 to 0.013, P = 0.075), and proportion of CABG (coefficient - 0.001, 95% CI - 0.003 to 0.0003, P = 0.096) were significantly associated with SBI incidence.

CONCLUSION

From the meta-regression, we concluded that advanced age and diabetes were related to increased SBI incidence after on-pump cardiac surgery, while CABG procedure alone was associated with less SBI onset. Studies with more accurate diagnoses of SBI are required to add more conclusive evidence to the field.

Silent stroke in patients with atrial fibrillation: Prevalence and predictive factors

BACKGROUND

Silent strokes are damagesof brain not accompanied by symptoms suggestive of stroke. Currentepidemiological trends suggesttheirindependent association with atrial fibrillation (AF). However, this association is not yetwelldefined.

AIM

To assess the prevalence of silent stroke in AF and determine itspredictivefactors.

METHODS

We carried out a cross-sectional study enrolling 37 patients followed for non-valvular AF in the cardiologydepartment. All participants had a clinicalevaluation and brain MRI.

RESULTS

The mean age was 66 ± 7 yearswith asex ratio (M / F) of 0.76. The mostcommon class of AF was the persistent form (70%). Oral anticoagulant therapywasprescribedin 32 patients (94.1%). Silent strokewerereported in 9 patients (24.3%). Age ≥72 years and CHA2DS2VASc score ≥ 4 weresignificantlyassociatedwith silent strokes in the univariate study withsensitivities of 77.8% and 62.5% respectively and specificities of 78.6% and 92.3% respectively. In the multivariate study, only CHA2DS2VASc score ≥ 4 wasconsidered to be an independentpredictor of silent stroke in AF (p = 0.004; adjusted OR = 20; CI95%: 2.6-152.6).

CONCLUSIONS

Our resultsregarding the association between silent strokesand AF confirmedpreviousevidence. Screening for theselesions in AF patients at high thromboembolicriskappears to be a relevant approachgiventheirpoorprognosis.

Lacunar Stroke Lesion Extent and Location and White Matter Hyperintensities Evolution 1 Year Post-lacunar Stroke

Lacunar strokes are a common type of ischemic stroke. They are associated with long-term disability, but the factors affecting the dynamic of the infarcted lesion and the brain imaging features associated with them, reflective of small vessel disease (SVD) severity, are still largely unknown. We investigated whether the distribution, volume and 1-year evolution of white matter hyperintensities (WMH), one of these SVD features, relate to the extent and location of these infarcts, accounting for vascular risk factors. We used imaging and clinical data from all patients [n = 118, mean age 64.9 (SD 11.75) years old] who presented to a regional hospital with a lacunar stroke syndrome within the years 2010 and 2013 and consented to participate in a study of stroke mechanisms. All patients had a brain MRI scan at presentation, and 88 had another scan 12 months after. Acute lesions (i.e., recent small subcortical infarcts, RSSI) were identified in 79 patients and lacunes in 77. Number of lacunes was associated with baseline WMH volume (B = 0.370, SE = 0.0939, P = 0.000174). RSSI volume was not associated with baseline WMH volume (B = 3.250, SE = 2.117, P = 0.129), but predicted WMH volume change (B = 2.944, SE = 0.913, P = 0.00184). RSSI location was associated with the spatial distribution of WMH and the pattern of 1-year WMH evolution. Patients with the RSSI in the centrum semiovale (n = 33) had significantly higher baseline volumes of WMH, recent and old infarcts, than patients with the RSSI located elsewhere [median 33.69, IQR (14.37 50.87) ml, 0.001 ≤ P ≤ 0.044]. But patients with the RSSI in the internal/external capsule/lentiform nucleus experienced higher increase of WMH volume after a year [n = 21, median (IQR) from 18 (11.70 31.54) ml to 27.41 (15.84 40.45) ml]. Voxel-wise analyses of WMH distribution in patients grouped per RSSI location revealed group differences increased in the presence of vascular risk factors, especially hypertension and recent or current smoking habit. In our sample of patients presenting to the clinic with lacunar strokes, lacunar strokes extent influenced WMH volume fate; and RSSI location and WMH spatial distribution and dynamics were intertwined, with differential patterns emerging in the presence of vascular risk factors. These results, if confirmed in wider samples, open potential avenues in stroke rehabilitation to be explored further.

Risk Factors of New Cerebral Infarctions After Endovascular Treatment for Basilar Artery Stenosis Based on High-Resolution Magnetic Resonance Imaging

Objective: The current study aims to analyze the risk factors of new cerebral infarctions in the distribution of basilar artery (BA) detected by diffusion-weighted imaging (DWI) after endovascular treatment in patients with severe BA stenosis. Methods: Data was collected from the electronic medical records of patients with severely atherosclerotic basilar artery stenosis (≥70%) who underwent endovascular treatment. The plaque characteristics, including the plaque distribution, plaque burden, plaque enhancement index, remodeling ratio, and stenosis degree, were evaluated qualitatively and quantitatively using high-resolution magnetic resonance imaging (HR-MRI) and digital subtraction angiography (DSA). The characteristics of the procedure, such as the type of treatment, balloon diameter, balloon length, stent diameter, and stent length, were analyzed. Results: A total of 107 patients with severe basilar artery stenosis (≥70%) who underwent endovascular treatment were enrolled. The study participants included 77 men and 30 women, with an average age of 61.6 ± 8.1 years. The rate of postoperative new cerebral infarctions was 55.1% (59/107), of which 74.6% (44/59) were caused by artery-to-artery embolism, 6.8% (4/59) due to perforator occlusion, and 18.6% (11/59) were caused by a mixed mechanism. Twelve of 59 patients had ischemic events, with nine cases of stroke and three cases of transient ischemic attacks (TIA). The plaque burden in the DWI-positive group was significantly larger than that in the DWI-negative group (3.7% vs. -8.5%, p = 0.016). Positive remodeling was more common in the DWI-positive group than in the DWI-negative group (35.6% vs. 16.7%, p = 0.028). Smoking was inversely correlated with the rate of new cerebral infarctions (odds ratio, 0.394; 95% confidence interval, 0.167-0.926; p = 0.033). Conclusion: The plaque characteristics are not associated with new cerebral infarctions in the distribution of BA, although a large plaque burden and positive remodeling are more likely to appear in patients with new cerebral infarctions after BA stenting, which warrants further studies with a larger sample size. As for smoking, the inverse correlation with new cerebral infarctions in the BA territory needs large-scale prospective randomized controlled trials to verify.

A model of silent brain infarction induced by endovascular intervention with balloon in cynomolgus macaques: A pilot study

Silent brain infarction is a special type of cerebral infarction, which can be detected by MRI or CT. The most patients with silent brain infarction show no symptoms, but some have mild depression, vascular dementia and other symptoms that are easily overlooked. Silent brain infarction is one of the risk factors for symptomatic cerebral infarction, it can develop into symptomatic cerebral infarction placing a heavy burden on families and society. Therefore, it's prevention and treatment should be as important as symptomatic cerebral infarction. However, the pathogenesis of silent brain infarction has not been elucidated. Studies have shown that silent brain infarction models have been established in rats and mice. But compared with other animals, non-human primates are more similar to humans in neuroanatomical structure and clinical characteristics. Therefore, this study is the first time to explore the silent brain infarction model in cynomolgus macaques. In this study, a model of silent brain infarction was established by endovascular intervention using balloon occlusion at the end of internal carotid artery for 45 min, which can lay a foundation for the future research on the pathological mechanism of silent brain infarction.

Silent cerebral infarcts in patients with sickle cell disease: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Silent cerebral infarcts (SCIs) are the most common neurological complication in children and adults with sickle cell disease (SCD). In this systematic review, we provide an overview of studies that have detected SCIs in patients with SCD by cerebral magnetic resonance imaging (MRI). We focus on the frequency of SCIs, the risk factors involved in their development and their clinical consequences.

METHODS

The databases of Embase, MEDLINE ALL via Ovid, Web of Science Core Collection, Cochrane Central Register of Trials via Wiley and Google Scholar were searched from inception to June 1, 2019.

RESULTS

The search yielded 651 results of which 69 studies met the eligibility criteria. The prevalence of SCIs in patients with SCD ranges from 5.6 to 80.6% with most studies reported in the 20 to 50% range. The pooled prevalence of SCIs in HbSS and HbSβ⁰ SCD patients is 29.5%. SCIs occur more often in patients with the HbSS and HbSβ⁰ genotype in comparison with other SCD genotypes, as SCIs are found in 9.2% of HbSC and HbSβ⁺ patients. Control subjects showed a mean pooled prevalence of SCIs of 9.8%. Data from included studies showed a statistically significant association between increasing mean age of the study population and mean SCI prevalence. Thirty-three studies examined the risk factors for SCIs. The majority of the risk factors show no clear association with prevalence, since more or less equal numbers of studies give evidence for and against the causal association.

CONCLUSIONS

This systematic review and meta-analysis shows SCIs are common in patients with SCD. No clear risk factors for their development were identified. Larger, prospective and controlled clinical, neuropsychological and neuroimaging studies are needed to understand how SCD and SCIs affect cognition.

Platelet-Reactive Antibodies in Patients after Ischaemic Stroke-An Epiphenomenon or a Natural Protective Mechanism

Ischaemic brain damage induces autoimmune responses, including the production of autoantibodies with potential neuroprotective effects. Platelets share unexplained similarities with neurons, and the formation of anti-platelet antibodies has been documented in neurological disorders. The aim of this study was to investigate the presence of anti-platelet antibodies in the peripheral blood of patients after ischaemic stroke and determine any clinical correlations. Using a flow cytometry-based platelet immunofluorescence method, we detected platelet-reactive antibodies in 15 of 48 (31%) stroke patients and two of 50 (4%) controls (p < 0.001). Western blotting revealed heterogeneous reactivities with platelet proteins, some of which overlapped with brain proteins. Stroke patients who carried anti-platelet antibodies presented with larger infarcts and more severe neurological dysfunction, which manifested as higher scores on the National Institutes of Health Stroke Scale (NIHSS; p = 0.009), but they had a greater recovery in the NIHSS by the time of hospital discharge (day 7 ± 2) compared with antibody-negative patients (p = 0.043). Antibodies from stroke sera reacted more strongly with activated platelets (p = 0.031) and inhibited platelet aggregation by up to 30.1 ± 2.8% (p < 0.001), suggesting the potential to interfere with thrombus formation. In conclusion, platelet-reactive antibodies can be found in patients soon after ischaemic stroke and correlate with better short-term outcomes, suggesting a potential novel mechanism limiting thrombosis.

The etiology, manifestations, and therapy of chronic cerebrovascular diseases

The paper presents the current etiopathogenetic classification of chronic cerebrovascular diseases (CVD) and discusses the role of hypertension, cerebral amyloid angiopathy, and genetically determined syndromes in the development of this pathological condition. It gives recommendations for the neuroradiological diagnosis of chronic CVD in accordance with the international standards. The paper discusses the clinical manifestations of chronic CVD, primarily vascular cognitive impairment. It discusses international guidelines for the examination and treatment of patients with chronic CVD, as well as the rules for stroke prevention in this patient cohort. The possibilities of pathogenetically based therapy in decreasing the severity of vascular cognitive impairment in the presence of chronic CVD are also highlighted.

Clinical management of cerebral small vessel disease: a call for a holistic approach

ABSTRACT

Cerebral small vessel disease (SVD) is a common global brain disease that causes cognitive impairment, ischemic or hemorrhagic stroke, problems with mobility, and neuropsychiatric symptoms. The brain damage, seen as focal white and deep grey matter lesions on brain magnetic resonance imaging (MRI) or computed tomography (CT), typically accumulates "covertly" and may reach an advanced state before being detected incidentally on brain scanning or causing symptoms. Patients have typically presented to different clinical services or been recruited into research focused on one clinical manifestation, perhaps explaining a lack of awareness, until recently, of the full range and complexity of SVD.In this review, we discuss the varied clinical presentations, established and emerging risk factors, relationship to SVD features on MRI or CT, and the current state of knowledge on the effectiveness of a wide range of pharmacological and lifestyle interventions. The core message is that effective assessment and clinical management of patients with SVD, as well as future advances in diagnosis, care, and treatment, will require a more "joined-up"' approach. This approach should integrate clinical expertise in stroke neurology, cognitive, and physical dysfunctions. It requires more clinical trials in order to improve pharmacological interventions, lifestyle and dietary modifications. A deeper understanding of the pathophysiology of SVD is required to steer the identification of novel interventions. An essential prerequisite to accelerating clinical trials is to improve the consistency, and standardization of clinical, cognitive and neuroimaging endpoints.

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.

The central nervous system and heart failure

The view that chronic heart failure was exclusively a disease of the heart dominated the cardiovascular literature until relatively recently. However, over the last 40 years it has increasingly come to be seen as a multisystem disease. Aside from changes in the sympathetic and parasympathetic nervous systems and the renin-angiotensin-aldosterone system, adaptations to the lungs, muscles and gastrointestinal tract have been clearly documented. It is clear that the brain and CNS are also affected in patients with heart failure, although this is often under recognized. The purpose of this review is to summarize the changes in the structure and biochemical function of the CNS in patients with chronic heart failure and to discuss their potential importance.

Serum and CSF Metabolites in Stroke-Free Patients Are Associated With Vascular Risk Factors and Cognitive Performance

Background and purpose: The aggregation of vascular risk factors (VRFs) can aggravate cognitive impairment in stroke-free patients. Metabolites in serum and cerebrospinal fluid (CSF) may irreversibly reflect early functional deterioration. This study evaluated small-molecule metabolites (<1,000 Da) in the serum and CSF of patients with different degrees of cerebrovascular burden and investigated the correlation between metabolism and cognitive performance associated with VRFs.

Methods: The subjects were divided into a low-risk group (10-year stroke risk ≤ 5%), a middle-risk group (10-year stroke risk >5% and <15%), and a high-risk group (10 years stroke risk ≥ 15%) according to the Framingham stroke risk profile (FSRP) score, which was used to quantify VRFs. We assess the cognitive function of the participants. We semiquantitatively quantified the small molecules using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The correlation between the small molecules and cognitive function, along with VRFs, was investigated to identify key small molecules and possible underlying metabolic pathways.

Results: When the FSRP scores increased, the cognitive performances of the subjects decreased, specifically the performance regarding the tasks of immediate memory, delayed recall, and executive function. Seven metabolites (2-aminobutyric acid, Asp Asp Ser, Asp Thr Arg, Ile Cys Arg, 1-methyluric acid, 3-tert-butyladipic acid, and 5α-dihydrotestosterone glucuronide) in serum and three metabolites [Asp His, 13-HOTrE(r), and 2,5-di-tert-Butylhydroquinone] in CSF were significantly increased, and one metabolite (arachidonoyl PAF C-16) in serum was significantly decreased in high-risk group subjects. Among these metabolites, 1-methyluric acid, 3-tert-butyladipic, acid and Ile Cys Arg in serum and 13-HOTrE(r), 2,5-di-tert-butylhydroquinone, and Asp His in CSF were found to be negatively related with cognitive performance in the high-risk group. Arachidonoyl PAF C-16 in serum was found to be associated with better cognitive performance. Caffeine metabolism and the tricarboxylic acid cycle (TCA cycle) were identified as key pathways.

Conclusions: 1-Methyluric acid, 3-tert-butyladipic acid, arachidonoyl PAF C-16, and Ile Cys Arg in serum and 13-HOTrE(r), 2,5-di-tert-butylhydroquinone, and Asp His in CSF were identified as potential biomarkers of vascular cognitive impairment (VCI) at the early stage. Caffeine metabolism and the TCA cycle may play important roles in the pathophysiology of VRF-associated cognitive impairment.

Noninvasive model for predicting future ischemic strokes in patients with silent lacunar infarction using radiomics

Background

This study aimed to investigate integrating radiomics with clinical factors in cranial computed tomography (CT) to predict ischemic strokes in patients with silent lacunar infarction (SLI).

Methods

Radiomic features were extracted from baseline cranial CT images of patients with SLI. A least absolute shrinkage and selection operator (LASSO)–Cox regression analysis was used to select significant prognostic factors based on Model^C with clinical factors, Model^R with radiomic features, and Model^CR with both factors. The Kaplan–Meier method was used to compare stroke-free survival probabilities. A nomogram and a calibration curve were used for further evaluation.

Results

Radiomic signature (p < 0.01), age (p = 0.09), dyslipidemia (p = 0.03), and multiple infarctions (p = 0.02) were independently associated with future ischemic strokes. Model^CR had the best accuracy with 6-, 12-, and 18-month areas under the curve of 0.84, 0.81, and 0.79 for the training cohort and 0.79, 0.88, and 0.75 for the validation cohort, respectively. Patients with a Model^CR score < 0.17 had higher probabilities of stroke-free survival. The prognostic nomogram and calibration curves of the training and validation cohorts showed acceptable discrimination and calibration capabilities (concordance index [95% confidence interval]: 0.7864 [0.70–0.86]; 0.7140 [0.59–0.83], respectively).

Conclusions

Radiomic analysis based on baseline CT images may provide a novel approach for predicting future ischemic strokes in patients with SLI. Older patients and those with dyslipidemia or multiple infarctions are at higher risk for ischemic stroke and require close monitoring and intensive intervention.

Risk Factors for Aphasia in Cerebral Small Vessel Diseases

BACKGROUND

Lacunes and white matter hyperintensities (WMH) are two common findings seen on neuroimaging in patients with cerebral small vessel disease (cSVD). Clinically we observed that some patients with cSVD have aphasia through the language assessment scale. Our study aimed to explore the underlying risk factors for aphasia in cSVD patients.

METHODS

This study retrospectively analyzed 38 patients, with and without aphasia, aged 50 or over, Chinese Han population, diagnosed as cSVD with lacunes and/or WMH. We collected demographic characteristics and vascular risk factors. The severity of WMH was assessed by the age related white matter changes (ARWMC) rating scale.

RESULTS

Risk factors associated with aphasia were: lower education (p = 0.029), higher total cholesterol (TC) levels (p = 0.023), and higher low-density lipoprotein cholesterol (LDL-C) levels (p = 0.027). After controlling for age and sex, levels of TC (odds ratios, 1.96; 95% confidence interval, 1.06-3.62; p = 0.032) remained associated with aphasia independently.

CONCLUSION

High level of TC was significantly associated with a higher risk of aphasia in clinically silent cSVD patients. Early interventions including lipid-lowering treatment, cranial magnetic resonance imaging (MRI) and ARWMC rating scale should be performed. Further studies are needed to explore proper methods of prevention and treatment for aphasia in clinically silent cSVD patients, in addition to understanding the pathophysiological mechanism.

Prevalence and risk factors of silent brain infarcts in patients with AF detected by 3T-MRI

BACKGROUND

Silent brain infarcts (SBI), a finding on neuroimaging, are associated with higher risk of future stroke. Atrial Fibrillation (AF) has been previously identified as a cause of SBI.

OBJECTIVES

The aim of this study is to determine the prevalence of and risk factors for SBI in patients with AF and low-to-moderate embolic risk according to CHADS₂ and CHA₂DS₂VASc score.

METHODS

Patients with a history of AF based on medical records who scored 0-1 in the CHADS₂ score were selected from the Seville urban area using the Andalusian electronic healthcare database (DIRAYA). Demographic and clinical data were collected and a 3T brain MRI was performed on patients older than 50 years and with absence of neurological symptoms.

RESULTS

66 of the initial 443 patients (14.9%) and 41 of the 349 patients with low risk according to CHA₂DS₂VASc score (11.7%) presented at least 1 SBI. After adjusted multivariable analysis, an older age (OR 3.84, 95% CI 1.07-13.76) and left atrial (LA) enlargement (OR 3.13, 95% CI 1.15-8.55) were associated with SBI in the whole cohort, while only LA enlargement was associated with SBI in the low-risk cohort (OR 3.19, 95% CI 1.33-7.63).

CONCLUSIONS

LA enlargement on echocardiogram was associated with SBI in patients with AF and low or moderate embolic risk according to CHADS₂ and in the low-risk population according to CHA₂DS₂VASc. Although further studies are needed, a neuroimaging screening might be justified in these patients to guide medical therapies to improve stroke prevention.

Incident cerebral lacunes: A review

Lacunes on magnetic resonance imaging (MRI) are considered as a key hallmark for evaluating the progression and severity of cerebral small vessel diseases. We aimed to review the MRI diagnostic criteria, frequency, predictors and clinical impact of incident lacunes in the largest longitudinal studies. Analyses were restricted to cohort studies of more than 50 individuals that investigated incident lacunes over a duration of at least one year. We observed that: (1) MRI parameters and definition of lacunes are inconsistent across studies, (2) the frequency of incident lacunes is strongly related to the previous clinical and MRI status at individual level, (3) both age and hypertension diagnosed at onset predict incident lacunes but the exact impact of blood pressure level during follow-up remains undetermined, (4) the clinical correlates of these lesions on cognition are repeatedly observed but the exact consequences on motor or gait performances are not always evaluated. Homogenization of imaging techniques, the use of strict diagnostic criteria and a broader clinical assessment considering motor and gait performances should be recommended in future longitudinal studies of incident lacunes including clinical trials testing preventative treatments in cerebral small vessel diseases.

Association between KCNQ2, TCF4 and RGS18 polymorphisms and silent brain infarction based on whole‑exome sequencing

Silent brain infarction (SBI) is a cerebral infarction identified through brain imaging. In particular, studies have shown that the presence of SBI in elderly patients increases their risk of cognitive dysfunction, impairment and dementia. However, little research has been published on the relevance of SBI to these risks for the Korean population. The association between potassium voltage‑gated channel subfamily Q member 2 (KCNQ2), transcription factor 4 (TCF4) and regulator of G‑protein signaling 18 (RGS18) genotypes and SBI were investigated using whole‑exome sequencing and PCR restriction fragment length polymorphism (RFLP) analysis. The study population included 407 patients with SBI (171 males) and 401 control subjects (172 males). Genotyping was performed using PCR RFLP. Interestingly, TCF4 rs9957668T>C polymorphisms were associated with SBI prevalence [TT vs. CC: adjusted odds ratio (AOR), 1.815, 95% confidence intervals (CI), 1.202‑2.740; TT vs. TC+CC: AOR, 1.492, 95% CI, 1.066‑2.088; TT+TC vs. CC: AOR, 1.454, 95% CI, 1.045‑2.203]. The combination of KCNQ2 rs73146513A>G and TCF4 rs9957668T>C genotypes was associated with increasing SBI prevalence (AG/CC: AOR, 3.719, 95% CI, 1.766‑7.833; AA/CC: AOR, 3.201, 95% CI, 1.387‑7.387). The present study showed that TCF4 rs9957668T>C polymorphisms may be risk factors for SBI. Therefore, the TCF4 rs9957668T>C polymorphism may serve as a biomarker for increased risk of SBI in the Korean population.

Overexpression of cortistatin alleviates oxygen/glucose-deprivation-induced ER stress and prompts neural stem cell proliferation via SSTR2

Cerebral infarction (CI), a blood circulatory disorder, causes a high mortality and disability rate worldwide. Intriguingly, a newly discovered neuropeptide, Cortistatin (CST), has been indicated to inhibit the cortical activity. In our research, we aimed to explore the functional relevance of CST in neural stem cells (NSCs) in CI rats. The expression of CST was determined in NSCs induced by oxygen-glucose deprivation (OGD). NSCs isolated from the embryonic rat brain were treated with OGD to establish an in vitro CI model while dithiothreitol (DTT) was introduced to induce endoplasmic reticulum stress (ERS), which were evaluated by assessment of GRP94, caspase-12 and CHOP expression. Then CST expression was restored by transfection of oe-CST, followed by assessment of NSC proliferation ability and cytotoxicity. Finally, the expression of CST and its receptor Somatostatin receptor subtype 2 (SSTR2) was quantified for mechanism exploration. CST was downregulated in CI, which was further confirmed in NSCs under OGD treatment. Overexpressed CST was found to promote cell activity and attenuate OGD-induced cytotoxicity of NSCs. Meanwhile, it was observed that the injured proliferation ability of NSCs was restored by CST overexpression. Besides, lower expression of GRP94, caspase-12 and CHOP was indicative of suppressed occurrence of ERS by CST. Mechanically, CST inhibited ERS through SSTR2. CST could facilitate the proliferation of NSCs in CI induced by OGD, ultimately highlighting a novel therapeutic target for CI treatment.

Assessment of the impact of EHR heterogeneity for clinical research through a case study of silent brain infarction

Background

The rapid adoption of electronic health records (EHRs) holds great promise for advancing medicine through practice-based knowledge discovery. However, the validity of EHR-based clinical research is questionable due to poor research reproducibility caused by the heterogeneity and complexity of healthcare institutions and EHR systems, the cross-disciplinary nature of the research team, and the lack of standard processes and best practices for conducting EHR-based clinical research.

Method

We developed a data abstraction framework to standardize the process for multi-site EHR-based clinical studies aiming to enhance research reproducibility. The framework was implemented for a multi-site EHR-based research project, the ESPRESSO project, with the goal to identify individuals with silent brain infarctions (SBI) at Tufts Medical Center (TMC) and Mayo Clinic. The heterogeneity of healthcare institutions, EHR systems, documentation, and process variation in case identification was assessed quantitatively and qualitatively.

Result

We discovered a significant variation in the patient populations, neuroimaging reporting, EHR systems, and abstraction processes across the two sites. The prevalence of SBI for patients over age 50 for TMC and Mayo is 7.4 and 12.5% respectively. There is a variation regarding neuroimaging reporting where TMC are lengthy, standardized and descriptive while Mayo’s reports are short and definitive with more textual variations. Furthermore, differences in the EHR system, technology infrastructure, and data collection process were identified.

Conclusion

The implementation of the framework identified the institutional and process variations and the heterogeneity of EHRs across the sites participating in the case study. The experiment demonstrates the necessity to have a standardized process for data abstraction when conducting EHR-based clinical studies.

Preventing Covert Brain Infarct-Related Cognitive Impairment and Dementia

Covert brain infarcts (CBIs) are five times more prevalent than symptomatic brain infarcts. CBIs are associated with cognitive impairment and therefore may be a target for preventing cognitive decline and dementia. This review focuses on strategies for preventing CBI-related cognitive impairment, either by preventing incident or recurrent CBI or by enhancing cognitive reserve. CBIs begin to become prevalent during midlife and are highly prevalent in later life. The distribution of vascular pathologies of CBI differs from those that cause symptomatic stroke; therefore, preventive treatments may need to differ as well. Only a few randomized clinical trials have provided data on CBI prevention, without conclusive results. Limited data suggest that higher early-life education, hypothesized to enhance cognitive reserve, can protect the brain from effects of CBI.

Self-Reported Fatigue Predicts Incident Stroke in a General Population: EPIC-Norfolk Prospective Population-Based Study

Background and Purpose- Fatigue is a common symptom among stroke survivors and in general practice. However, the clinical significance of fatigue and its relationship to incident stroke is unclear. The aim of this study was to examine the relationship between self-reported fatigue and the incidence of stroke in a general population. Methods- This was a prospective, population-based study. The study population was 15 654 men and women aged 39 to 79 years recruited in 1993 to 1997 and followed till March 2016. Fatigue was assessed at 18 months after baseline using the vitality domain of the Short Form 36 questionnaire. Cox proportional hazard models were constructed to describe the prospective relationship between baseline fatigue and incident stroke adjusting for age, sex, systolic blood pressure, cholesterol, physical activity, smoking status, alcohol consumption, fruit and vegetable consumption, diabetes mellitus, body mass index, vitamin supplement use, education level, Townsend deprivation index, and occupational social class. Incident stroke was ascertained using death certificates and hospital record linkage data. Results- Through 249 248 person-years of follow-up, 1509 incident strokes occurred. Participants who reported the highest level of fatigue (quartile 4) were more likely to be women, to be multimorbid, and to perceive their health as fair or poor. We observed ≈50% relative risk increase in stroke risk (hazard ratio, 1.49 [95% CI, 1.29-1.71]) in those who reported the highest level of fatigue compared with those who reported the lowest level of fatigue (Q4 versus Q1). This relationship remained unaltered regardless of anemia status, the presence or absence of chronic bronchitis, thyroid dysfunction, or depression. Conclusions- Self-report fatigue assessed by the vitality domain of the Short Form 36 questionnaire predicts the risk of future stroke at the general population level. Identifying and addressing stroke risk factors in those who report fatigue in general practice may have substantial benefit at the population level.

Nighttime hypoxia affects global cognition, memory, and executive function in community-dwelling individuals with hypertension

STUDY OBJECTIVES

The objective of this study was to determine which respiratory and architectural sleep parameters are related to cognitive function and cognitive status (mild cognitive impairment [MCI] versus normal cognitive aging [NCA]) in community-dwelling individuals with hypertension. Additionally, it aimed to determine whether the results changed in the presence or absence of vascular brain lesions (silent brain infarcts and extensive white matter hyperintensities [WMHs]).

METHODS

In a cohort of individuals with hypertension and without previous stroke or dementia, we conducted in-hospital polysomnography including electroencephalography, electro-oculography, electromyography, and magnetic resonance imaging to assess silent brain infarcts and WMHs. Cognitive testing was carried out with a screening test (Dementia Rating Scale version 2 [DRS-2]) and a complete cognitive visit.

RESULTS

This study included 158 participants with a median age of 65.0 years; 32.3% were females, and the median apnea-hypopnea index was 22.3 events/h. MCI was diagnosed in 24 study participants, and the rest had NCA. Regarding respiratory parameters, total DRS-2 scores (β; 95% CI) 0.121; 0.026, 0.215 were positively associated with mean O₂ saturation, whereas total (-0.022; -0.036, -0.009), executive function (-0.016; -0.026, -0.006) and memory (-0.017; -0.029, -0.004) DRS-2 scores were all negatively associated with the percent of time with oxygen saturation < 90% after correcting for education, vascular risk factors, and magnetic resonance imaging lesions. Regarding sleep architecture, Attention DRS-2 scores (0.0153; 0.001, 0.306) were independently associated with total sleep time. Similar results were obtained in the absence of silent brain infarcts or WMHs in the stratified analysis. None of the sleep parameters were associated with cognitive status.

CONCLUSIONS

Low oxygen saturation contributes to cognitive performance, and this effect appears even in the absence of vascular brain lesions in individuals with hypertension.

Neurovascular unit dysregulation, white matter disease, and executive dysfunction: the shared triad of vascular cognitive impairment and Alzheimer disease

Executive dysfunction is the most important predictor for loss of independence in dementia. As executive function involves the coordination of distributed cerebral functions, executive function requires healthy white matter. However, white matter is highly vulnerable to cerebrovascular insults, with executive dysfunction being a core feature of vascular cognitive impairment (VCI). At the same time, cerebrovascular pathology, white matter disease, and executive dysfunction are all increasingly recognized as features of Alzheimer disease (AD). Recent studies have characterized the crucial role of glial cells in the pathological changes observed in both VCI and AD. In comorbid VCI and AD, the glial cells of the neurovascular unit (NVU) emerge as important therapeutic targets for the preservation of white matter integrity and executive function. Our synthesis from current research identifies dysregulation of the NVU, white matter disease, and executive dysfunction as a fundamental triad that is common to both VCI and AD. Further study of this triad will be critical for advancing the prevention and management of dementia.

Association of postoperative covert stroke and cognitive dysfunction among elderly patients undergoing non-cardiac surgery: protocol for a prospective cohort study (PRECISION study)

INTRODUCTION

The incidence of covert stroke and cognitive dysfunction has gradually increased due to an ageing population. Recently, a prospective cohort study reported perioperative covert stroke was associated with an increased risk of postoperative cognitive dysfunction (POCD) 1 year after non-cardiac surgery. However, the mechanism remains unclear.

METHODS AND ANALYSIS

This is a prospective observational trial aiming to investigate the cumulative incidence of perioperative covert stroke and test the hypothesis that perioperative covert stroke associates with POCD in elderly patients undergoing non-cardiac and non-neurological surgery. Data on risk factors, brain MRI, cognitive function evaluation and serum immune-inflammatory cytokines will be collected and analysed.

ETHICS AND DISSEMINATION

Ethical approval has been granted by the Medical Ethics Committee of Beijing Tiantan Hospital, Capital Medical University (reference number: KY2017-027-02). The results of this study will be disseminated through presentations at scientific conferences and publication in scientific journals.

TRIAL REGISTRATION NUMBER

NCT03081429.

Cholesterol Variability and Cranial Magnetic Resonance Imaging Findings in Older Adults: The Cardiovascular Health Study

Background and Purpose- Serum cholesterol variability, independent of mean, has been associated with stroke, white matter hyperintensities on cranial magnetic resonance imaging (MRI), and other cardiovascular events. We sought to assess the relationship between total serum cholesterol (TC) variability and cranial MRI findings of subclinical or covert vascular brain injury in a longitudinal, population-based cohort study of older adults. Methods- In the Cardiovascular Health Study, we assessed associations between intraindividual TC mean, trend, and variability over ≈5 years with covert brain infarction (CBI) and white matter grade (WMG) on cranial MRI. Mean TC was calculated for each study participant from 4 annual TC measurements between 2 MRI scans. TC trend was calculated as the slope of the linear regression of the TC measurements, and TC variability was calculated as the SD of the residuals from the linear regression. We evaluated the association of intraindividual TC variability with incident CBI and worsening WMG between 2 MRI scans in primary analyses and with prevalent CBI number and WMG on the follow-up MRI scan in secondary analyses. Results- Among participants who were eligible for the study and free of clinical stroke before the follow-up MRI, 17.9% of 1098 had incident CBI, and 27.8% of 1351 had worsening WMG on the follow-up MRI. Mean, trend, and variability of TC were not associated with these outcomes. TC variability, independent of mean and trend, was significantly associated with the number of CBI (β=0.009 [95% CI, 0.003-0.016] P=0.004; N=1604) and was associated with WMG (β, 0.009 [95% CI, -0.0002 to 0.019] P=0.055; N=1602) on the follow-up MRI. Conclusions- Among older adults, TC variability was not associated with incident CBI or worsening WMG but was associated with the number of prevalent CBI on cranial MRI. More work is needed to validate and to clarify the mechanisms underlying such associations.

Association Between Central Blood Pressure and Subclinical Cerebrovascular Disease in Older Adults

Elevated blood pressure (BP) level is one of the most consistently identified risk factors for silent brain disease. BP values obtained at the proximal segment of the aorta (central BP) are more directly involved than brachial BP in the pathogenesis of cardiovascular disease. However, the association between central BP and silent cerebrovascular disease has not been clearly established. Participants in the CABL (Cardiovascular Abnormalities and Brain Lesions) study (n=993; mean age, 71.7±9.3 years; 37.9% men) underwent 2-dimensional echocardiography, arterial wave reflection analysis for determination of central BPs, and brain magnetic resonance imaging. Central BPs were calculated from the radial pulse waveform. Subclinical silent cerebrovascular disease was defined as silent brain infarction and white matter hyperintensity volume. Both brachial (P=0.014) and central pulse pressure (P=0.026) were independently associated with silent brain infarctions after adjustment for clinical variables, but not adjusting for each other. None of the brachial BP values was associated with upper quartile of white matter hyperintensity volume in multivariable analysis. Both central systolic BP (P<0.001) and central pulse pressure (P<0.001) were significantly associated with upper quartile of white matter hyperintensity volume in multivariable analysis, even after adjustment for brachial BP. In a predominantly older population-based cohort, both brachial and central pulse pressure were independently associated with silent brain infarction. However, higher central systolic BP and central pulse pressure, but not brachial BP, were significantly associated with white matter hyperintensity volume.

Desiderata for delivering NLP to accelerate healthcare AI advancement and a Mayo Clinic NLP-as-a-service implementation

Data is foundational to high-quality artificial intelligence (AI). Given that a substantial amount of clinically relevant information is embedded in unstructured data, natural language processing (NLP) plays an essential role in extracting valuable information that can benefit decision making, administration reporting, and research. Here, we share several desiderata pertaining to development and usage of NLP systems, derived from two decades of experience implementing clinical NLP at the Mayo Clinic, to inform the healthcare AI community. Using a framework, we developed as an example implementation, the desiderata emphasize the importance of a user-friendly platform, efficient collection of domain expert inputs, seamless integration with clinical data, and a highly scalable computing infrastructure.

Association of obstructive sleep apnea and cerebral small vessel disease: a systematic review and meta-analysis

Study Objectives

The objective of the present study was to investigate the association between obstructive sleep apnea (OSA) and the presence of various neuroimaging marker of cerebral small vessel disease (CSVD).

Methods

We systematically searched PubMed, Embase, Web of Science, Scopus, and Cochrane library (from inception to May 2019) for studies evaluating the association between OSA and CSVD, which included white matter hyperintensities (WMH), silent brain infarction (SBI), cerebral microbleeds (CMBs), and perivascular spaces (PVS). Pooled odds ratios (ORs) with 95% confidence interval (CIs) were estimated using random-effects meta-analysis.

Results

After screening 7290 publications, 20 studies were finally included involving 6036 subjects. The sample size ranged from 27 to 1763 (median 158, interquartile range: 67–393). The meta-analysis showed that moderate to severe OSA was positively associated with WMH (13 studies, n = 4412, OR = 2.23, 95% CI = 1.53 to 3.25, I2 = 80.3%) and SBI (12 studies, n = 3353, OR 1.54, 95% CI = 1.06 to 2.23, I2 = 52%). There was no association with CMBs (three studies, n = 342, OR = 2.17, 95% CI = 0.61 to 7.73, I2 = 60.2%) or PVS (two studies, n = 267, OR = 1.56, 95% CI = 0.28 to 8.57, I2 = 69.5%). There was no relationship between mild OSA and CSVD.

Conclusion

Current evidence suggests that moderate to severe sleep apnea is positively related to WMH and SBI, but not CMBs or PVS, which suggests that OSA may contribute to the pathogenesis of CSVD. Further large cohort studies should be prioritized to confirm the findings.

Late-onset unexplained epilepsy: What are we missing?

With the aging of the US population, the incidence of epilepsy will increase, with 25 to 50% of new cases with no identifiable etiology diagnosed as late-onset unexplained epilepsy (LOUE). In the current targeted review, we discuss the possible role of cerebral small vessel ischemic disease, accumulation of amyloidβ and hyperphosphorylated tau, and sleep apnea as potential pathophysiologic mechanisms explaining LOUE. We highlight the impact of these processes on cognition and avenues for diagnosis and treatment.

Skeletal muscle function and need for long-term care of urban elderly people in Japan (the Bunkyo Health Study): a prospective cohort study

PURPOSE

The proportion of elderly individuals (age ≥65 years) in Japan reached 27.7% in 2017, the highest in the world. A serious social problem in a super-aged society is the rise in the number of elderly people who need long-term care (LTC), which is mainly due to cerebrovascular disease, dementia, age-related frailty, falls and fractures, and joint disease. We hypothesised that decreased muscle mass, muscle strength and insulin sensitivity are the common risk factors for these diseases related to needing LTC. We developed a prospective cohort study of elderly subjects in an urban community to test this hypothesis. The primary objective is to prospectively investigate associations between muscle mass, muscle strength, and insulin sensitivity and incidence of main disease and risk factors of needing LTC. The primary outcomes are the incidence of cerebrovascular disease and cognitive decline.

PARTICIPANTS

Participants were 1629 people aged 65-84 years living in 13 communities in an urban area (Bunkyo-ku, Tokyo, Japan). Average age was 73.1±5.4 years.

FINDINGS TO DATE

We obtained baseline data on cognitive function, cerebral small vessel disease (SVD) determined by brain MRI, body composition, bone mineral density, arteriosclerosis, physical function, muscle mass, muscle strength and insulin sensitivity. Mild cognitive impairment and dementia were observed in 18.1% and 3.3% of participants, respectively. The prevalence of cerebral SVD was 24.8%. These characteristics are similar to those previously reported in elderly Japanese subjects.

FUTURE PLANS

We will ask participants about their health status, including incidence of cerebrovascular disease, falls, fractures and other diseases every year by mail. We plan to re-evaluate cognitive function, brain MRI parameters and other parameters at 5 and 10 years after the baseline evaluation. We will evaluate whether low muscle function (muscle mass, muscle strength or insulin sensitivity) is a risk factor for cognitive decline or cerebrovascular disease.

Effects of adiposity and metabolic dysfunction on cognition: A review

Obesity and metabolic dysfunction are both correlated with increased rates of cognitive decline. However, because these two conditions often co-occur, it remains unclear whether their cognitive consequences are independent. In this review, we carefully consider literature examining the effects of metabolic dysfunction and increased adiposity on cognition across the lifespan, including only well-controlled studies that attempt to dissociate their effects. We found a total of 36 studies, 17 examining metabolic dysfunction and 19 examining the effects of adiposity. We found evidence from the literature suggesting that increased adiposity and metabolic dysfunction may contribute to deficits in executive function, memory, and medial temporal lobe structures largely independent of one another. These deficits are thought to arise principally from physiological changes associated with inflammation, vascularization, and oxidative stress, among others. Such processes may result from excess adipose tissue and insulin resistance that occur independently and can further exacerbate when the two conditions co-occur. However, we also find it likely that impaired cognition plays a role in behavioral and lifestyle choices that lead to increased adiposity and metabolic dysfunction, which can then perpetuate and augment cognitive decline. We recommend additional prospective and longitudinal studies to examine whether impaired cognition is a cause and/or consequence of these factors.

Sex-specific association of metabolic risk factors with brain ischemic lesions by severity and location

Background

Males and females exhibit significant differences in metabolism and in brain ischemic stroke and different features of brain ischemic lesions are related to different health outcomes. It is critical to understand sex differences in their associations to optimize prevention and intervention for both sexes. We aimed to investigate the sex-specific association of metabolic risk factors with brain ischemic lesions by severity and location.

Methods

Five thousand seven hundred ninety-one participants who underwent comprehensive health examinations between Jan. 1, 2017, and Dec. 31, 2017, were enrolled. Clinical and laboratory data about metabolic risk factors were obtained. Brain ischemic lesions were further categorized by severity (mild ischemic lesions or severe infarct lesions) and location (strictly lobar or deep brain/infratentorial areas) based on brain magnetic resonance imaging reports. Sex- and age-specific detected rates were calculated, and generalized linear models and multinomial logistic regression were used to analyze the associations between metabolic risk factors and the presence, severity, and location of ischemic lesions stratified by sex.

Results

A total of 2712 (46.8%) participants had at least one brain ischemic lesions. Age (adjusted OR, 1.10 [1.10–1.11], p < 0.001) and hypertension (adjusted OR, 1.42 [1.22–1.64], p < 0.001) were generally associated with higher risks of brain ischemia in both sexes. Metabolic syndrome was associated with greater adjusted ORs for brain ischemia with different severity and location in men (adjusted ORs between 1.23 and 1.49) but not in women. Overweight and obesity were related to lesions located strictly in lobar in men (adjusted OR, 1.23 and 1.33, respectively) and lesions located in deep brain/infratentorial areas in women (adjusted OR, 1.57 and 2.26, respectively).

Conclusions

Metabolic syndrome was associated with brain ischemic lesions in men but not in women. Higher body mass index was related to ischemic lesions located in lobar in men and in deep brain/infratentorial areas in women. Its mechanisms remain to be further investigated.