Cerebral small vessel disease and stroke: Linked by stroke aetiology, but not stroke lesion location or size

BACKGROUND

Cerebral small vessel disease (SVD) has previously been associated with worse stroke outcome, vascular dementia, and specific post-stroke cognitive deficits. The underlying causal mechanisms of these associations are not yet fully understood. We investigated whether a relationship between SVD and certain stroke aetiologies or a specific stroke lesion anatomy provides a potential explanation.

METHODS

In a retrospective observational study, we examined 859 patients with first-ever, non-SVD anterior circulation ischemic stroke (age = 69.0±15.2). We evaluated MRI imaging markers to assess an SVD burden score and mapped stroke lesions on diffusion-weighted MRI. We investigated the association of SVD burden with i) stroke aetiology, and ii) lesion anatomy using topographical statistical mapping.

RESULTS

With increasing SVD burden, stroke of cardioembolic aetiology was more frequent (ρ = 0.175; 95 %-CI = 0.103;0.244), whereas cervical artery dissection (ρ = -0.143; 95 %-CI = -0.198;-0.087) and a patent foramen ovale (ρ = -0.165; 95 %-CI = -0.220;-0.104) were less frequent stroke etiologies. However, no significant associations between SVD burden and stroke aetiology remained after additionally controlling for age (all p>0.125). Lesion-symptom-mapping and Bayesian statistics showed that SVD burden was not associated with a specific stroke lesion anatomy or size.

CONCLUSIONS

In patients with a high burden of SVD, non-SVD stroke is more likely to be caused by cardioembolic aetiology. The common risk factor of advanced age may link both pathologies and explain some of the existing associations between SVD and stroke. The SVD burden is not related to a specific stroke lesion location.

Influence of threshold selection and image sequence in in-vivo segmentation of enlarged perivascular spaces

BACKGROUND

Growing interest surrounds perivascular spaces (PVS) as a clinical biomarker of brain dysfunction given their association with cerebrovascular risk factors and disease. Neuroimaging techniques allowing quick and reliable quantification are being developed, but, in practice, they require optimisation as their limits of validity are usually unspecified.

NEW METHOD

We evaluate modifications and alternatives to a state-of-the-art (SOTA) PVS segmentation method that uses a vesselness filter to enhance PVS discrimination, followed by thresholding of its response, applied to brain magnetic resonance images (MRI) from patients with sporadic small vessel disease acquired at 3 T.

RESULTS

The method is robust against inter-observer differences in threshold selection, but separate thresholds for each region of interest (i.e., basal ganglia, centrum semiovale, and midbrain) are required. Noise needs to be assessed prior to selecting these thresholds, as effect of noise and imaging artefacts can be mitigated with a careful optimisation of these thresholds. PVS segmentation from T1-weighted images alone, misses small PVS, therefore, underestimates PVS count, may overestimate individual PVS volume especially in the basal ganglia, and is susceptible to the inclusion of calcified vessels and mineral deposits. Visual analyses indicated the incomplete and fragmented detection of long and thin PVS as the primary cause of errors, with the Frangi filter coping better than the Jerman filter.

COMPARISON WITH EXISTING METHODS

Limits of validity to a SOTA PVS segmentation method applied to 3 T MRI with confounding pathology are given.

CONCLUSIONS

Evidence presented reinforces the STRIVE-2 recommendation of using T2-weighted images for PVS assessment wherever possible. The Frangi filter is recommended for PVS segmentation from MRI, offering robust output against variations in threshold selection and pathology presentation.

Where is VALDO? VAscular Lesions Detection and segmentatiOn challenge at MICCAI 2021

Imaging markers of cerebral small vessel disease provide valuable information on brain health, but their manual assessment is time-consuming and hampered by substantial intra- and interrater variability. Automated rating may benefit biomedical research, as well as clinical assessment, but diagnostic reliability of existing algorithms is unknown. Here, we present the results of the VAscular Lesions DetectiOn and Segmentation (Where is VALDO?) challenge that was run as a satellite event at the international conference on Medical Image Computing and Computer Aided Intervention (MICCAI) 2021. This challenge aimed to promote the development of methods for automated detection and segmentation of small and sparse imaging markers of cerebral small vessel disease, namely enlarged perivascular spaces (EPVS) (Task 1), cerebral microbleeds (Task 2) and lacunes of presumed vascular origin (Task 3) while leveraging weak and noisy labels. Overall, 12 teams participated in the challenge proposing solutions for one or more tasks (4 for Task 1-EPVS, 9 for Task 2-Microbleeds and 6 for Task 3-Lacunes). Multi-cohort data was used in both training and evaluation. Results showed a large variability in performance both across teams and across tasks, with promising results notably for Task 1-EPVS and Task 2-Microbleeds and not practically useful results yet for Task 3-Lacunes. It also highlighted the performance inconsistency across cases that may deter use at an individual level, while still proving useful at a population level.

Relationship between glycemic variability and cognitive function in lacune patients with type 2 diabetes

BACKGROUND

Lacunes are the manifestations of lacunar infarction which can lead many patients to the clinical outcome of disability or dementia. However, the relationship between lacune burden, cognitive function and blood glucose fluctuation in patients with type 2 diabetes mellitus (T2DM) complicated with lacunes is not very clear.

AIM

To explore the correlation between glucose variability, lacune burden and cognitive function in patients with lacunes complicated with T2DM.

METHODS

The clinical and imaging data of 144 patients with lacunes combined with T2DM were reviewed retrospectively. 72 h continuous glucose monitoring was performed. The Montreal Cognitive Assessment was used to assess cognitive function. The burden of lacunes was evaluated using magnetic resonance imaging performance. Multifactorial logistic regression analysis was used to study the affecting the lacune load and cognitive impairment in patients. To predict the value of patients' cognitive impairment with lacunes complicated with T2DM, a receiver operating characteristic (ROC) curve and a nomogram prediction model were constructed.

RESULTS

The standard deviation (SD) of the average blood glucose concentration, percentage coefficient of variation (%CV) and time of range (TIR) were significantly different between the low and the high load groups (P < 0.05). The SD, %CV and TIR of the cognitive impairment group and non-cognitive impairment group were significantly different (P < 0.05). SD (odds ratio (OR): 3.558, 95% confidence interval (CI): 1.268-9.978, P = 0.006), and %CV (OR: 1.192, 95%CI: 1.081-1.315, P < 0.05) were the risk factors for an increased infarct burden in lacunes patients complicated with T2DM. TIR (OR: 0.874, 95%CI: 0.833-0.928, P < 0.05) is a protective factor. In addition, an increased SD (OR: 2.506, 95%CI: 1.008-6.23, P = 0.003), %CV (OR: 1.163, 95%CI: 1.065-1.270, P < 0.05) were the risk factors for cognitive impairment in patients with lacunes complicated with T2DM, TIR (OR: 0.957, 95%CI: 0.922-0.994, P < 0.05) is a protective factor. A nomogram prediction model of the risk of cognitive impairment was established based on SD, %CV and TIR. Decision curve analysis and the internal calibration analysis were used for internal verification and showed that the model was clinical benefit. The area under the ROC curves for predicting cognitive impairment in patients with lacunes complicated with T2DM was drawn were %CV: 0.757 (95%CI :0.669-0.845, P < 0.05), TIR: 0.711 (95%CI: 0.623-0.799, P < 0.05).

CONCLUSION

Blood glucose variability is closely associated with the level of lacune burden and cognitive dysfunction in lacune patients combined with T2DM. %CV, TIR have a certain predictive effect in cognitive impairment in lacune patients.

Association between Anatomical Variations of the Circle of Willis and Covert Vascular Brain Injury in the General Population

BACKGROUND AND PURPOSE

The circle of Willis (COW) is a circulatory anastomosis located at the base of the brain. Little is known about the association between covert vascular brain injury and COW configurations in the general population. We explored this relationship in a community-based Chinese sample.

METHODS

A total of 1,055 patients (mean age, 54.8 ± 8.9 years; 36.0% men) without intracranial arterial stenosis were included in the analysis. Magnetic resonance imaging was performed to evaluate the presence of imaging markers of covert vascular brain injury, including white matter hyperintensities (WMHs), lacunes, cerebral microbleeds (CMBs), enlarged perivascular spaces, and brain atrophy. Magnetic resonance angiography was used to classify the COW configurations according to the completeness, symmetry, and presence of the fetal posterior cerebral artery (FTP). The association between vascular lesions and variations in COW was analyzed.

RESULTS

Among the 1,055 patients, 104 (9.9%) had a complete COW. Completeness correlated with age (p = 0.001). Incomplete COW was positively associated with WMH severity (OR = 2.071; 95% CI, 1.004-4.270) and CMB presence (OR = 1.542; 95% CI, 1.012-2.348), independent of age and sex. The presence of FTP was associated with lacunes (OR = 1.878; 95% CI, 1.069-3.298), more severe WMHs (OR = 1.739; 95% CI, 1.064-2.842), and less severe enlarged perivascular spaces (OR = 0.562; 95% CI, 0.346-0.915).

CONCLUSIONS

COW configuration was significantly related to various covert vascular brain injuries.

Imaging of Normal Brain Aging

Understanding normal brain aging physiology is essential to improving healthy human longevity, differentiation, and early detection of diseases, such as neurodegenerative diseases, which are an enormous social and economic burden. Functional decline, such as reduced physical activity and cognitive abilities, is typically associated with brain aging. The authors summarize the aging brain mechanism and effects of aging on the brain observed by brain structural MR imaging and advanced neuroimaging techniques, such as diffusion tensor imaging and functional MR imaging.

Cerebral Small-Vessel Diseases: A Look Back from 1991 to Today

BACKGROUND

Cerebral small-vessel diseases (cSVDs) encompass a number of causes involving, but not limited to, alterations in the intracranial microvasculature, leading to the accumulation of brain tissue damage and the development of various degrees of cognitive impairment, behavioral alterations, gait instability, and localization signs, often associated with the occurrence of ischemic or hemorrhagic strokes.

SUMMARY

In 2021, although key questions remain unanswered, there is general agreement on the construct, its main pathophysiological bases, and the terms used to describe its main clinical and radiological features. However, this has not always been the case, and the 30th anniversary of Cerebrovascular Diseases is an opportunity to look back from 1991 to the present to understand how a number of features, sometimes considered independent, have been progressively brought together by successive scientific breakthroughs, gradually leading to the definition of the now widely accepted concept of cSVDs. Key Messages: In the course of this journey, we will detail with particular attention the role of what we consider 2 crucial events: the advent of cerebral MRI and the building of large cohorts with monogenic forms of small-vessel disease of the brain.

Patterns of progression of cerebral small vessel disease markers in older adults of Amerindian ancestry: a population-based, longitudinal prospective cohort study

BACKGROUND

Progression of cerebral small vessel disease (cSVD) markers has been studied in different races/ethnic groups. However, information from individuals of Amerindian ancestry is lacking. We sought to evaluate progression patterns of cSVD markers in community-dwelling older adults of Amerindian ancestry.

METHODS

Following a longitudinal prospective study design, participants of the Atahualpa Project Cohort aged ≥ 60 years received a baseline brain MRI and clinical interviews. Those who also received a brain MRI at the end of the study were included. Poisson regression models were fitted to assess cSVD markers progression according to their baseline load after a median follow-up of 6.5 ± 1.4 years. Logistic regression models were fitted to assess interrelations in the progression of the different cSVD markers at the end of the study.

RESULTS

The study included 263 individuals (mean age: 65.7 ± 6.2 years). Progression of white matter hyperintensities (WMH) was noticed in 103 (39%) subjects, cerebral microbleeds in 25 (12%), lacunes in 12 (5%), and enlarged basal ganglia-perivascular spaces (BG-PVS) in 56 (21%). Bivariate Poisson regression models showed significant associations between WMH severity at baseline and progression of WMH and enlarged BG-PVS. These associations became non-significant in multivariate models adjusted for clinical covariates. Logistic regression models showed interrelated progressions of WMH, cerebral microbleeds and enlarged BG-PVS. The progression of lacunes was independent.

CONCLUSIONS

Patterns of cSVD marker progression in this population of Amerindians are different than those reported in other races/ethnic groups. The independent progression of lacunes suggests different pathogenic mechanisms with other cSVD markers.

Associations of subclinical cerebral small vessel disease and processing speed in non-demented subjects: A 7-year study

Markers of cerebral small vessel disease (CSVD) have previously been associated with age-related cognitive decline. Using longitudinal data of cognitively healthy, older adults (N = 216, mean age at baseline = 70.9 years), we investigated baseline status and change in white matter hyperintensities (WMH) (total, periventricular, deep), normal appearing white matter (NAWM), brain parenchyma volume (BPV) and processing speed over seven years as well as the impact of different covariates by applying latent growth curve (LGC) models. Generally, we revealed a complex pattern of associations between the different CSVD markers. More specifically, we observed that changes of deep WMH (dWMH), as compared to periventricular WMH (pWMH), were more strongly related to the changes of other CSVD markers and also to baseline processing speed performance. Further, the number of lacunes rather than their volume reflected the severity of CSVD. With respect to the studied covariates, we revealed that higher education had a protective effect on subsequent total WMH, pWMH, lacunar number, NAWM volume, and processing speed performance. The indication of antihypertensive drugs was associated with lower lacunar number and volume at baseline and the indication of antihypercholesterolemic drugs came along with higher processing speed performance at baseline. In summary, our results confirm previous findings, and extend them by providing information on true within-person changes, relationships between the different CSVD markers and brain-behavior associations. The moderate to strong associations between changes of the different CSVD markers indicate a common pathological relationship and, thus, support multidimensional treatment strategies.

Cerebrovascular pathology in Alzheimer's disease: Hopes and gaps

Alzheimer's disease (AD) is recognized as multifactorial and heterogeneous disease with multiple contributors to its pathophysiology, including vascular dysfunction. Given that a revision of the AT(N) classification is expected in the near future, the present work supports the importance to add an additional vascular (V) category to the framework. In particular, we attempt to shed light on the vascular markers and risk factors that are currently ready-to-be-added to the framework: i) lacunes, ii) white matter hyperintensities and iii) microbleeds seen in Flair, T2* weighted imaging and susceptibility images (SWI). Next, we discuss the added value of other types of imaging, such as diffusion-based metrics and advanced perfusion sequences to encompass more subtle vascular dysfunction. Finally, we highlight the importance to add information about the following cardiovascular risk factors to the framework: history of hypertension, obesity, and diabetes. We believe that adding a V category to the AT(N) framework will improve AD classification and foster efforts to apply the right drug(s) at the right time in the right AD subgroups. Brief communication The present work supports the importance to add an additional vascular (V) category to the AT(N) framework and shed light on the vascular MRI markers and risk factors that are currently ready-to-be-added to the framework.

The INECO Frontal Screening for the Evaluation of Executive Dysfunction in Cerebral Small Vessel Disease: Evidence from Quantitative MRI in a CADASIL Cohort from Colombia

OBJECTIVES

Executive dysfunction is a predominant cognitive symptom in cerebral small vessel disease (SVD). The Institute of Cognitive Neurology Frontal Screening (IFS) is a well-validated screening tool allowing the rapid assessment of multiple components of executive function in Spanish-speaking individuals. In this study, we examined performance on the IFS in subjects with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), an inherited condition leading to the early onset of SVD. We further explored associations between performance on the IFS and magnetic resonance imaging (MRI) markers of SVD.

METHODS

We recruited 24 asymptomatic CADASIL subjects and 23 noncarriers from Colombia. All subjects underwent a research MRI and a neuropsychological evaluation, including the IFS. Structural MRI markers of SVD were quantified in each subject, together with an SVD Sum Score representing the overall burden of cerebrovascular alterations. General linear model, correlation, and receiver operating characteristic curve analyses were used to explore group differences on the IFS and relationships with MRI markers of SVD.

RESULTS

CADASIL subjects had a significantly reduced performance on the IFS Total Score. Performance on the IFS correlated with all quantified markers of SVD, except for brain atrophy and perivascular spaces enlargement. Finally, while the IFS Total Score was not able to accurately discriminate between carriers and noncarriers, it showed adequate sensitivity and specificity in detecting the presence of multiple MRI markers of SVD.

CONCLUSIONS

These results suggest that the IFS may be a useful screening tool to assess executive function and disease severity in the context of SVD.

Cerebral Perfusion and the Burden of Small Vessel Disease in Patients Referred to a Memory Clinic

BACKGROUND

Cerebral small vessel disease (SVD) lesions on MRI are common in patients with cognitive impairment. It has been suggested that cerebral hypoperfusion is involved in the etiology of these lesions.

OBJECTIVE

The aim of the study was to determine the relationship between cerebral blood flow (CBF) and SVD burden in patients referred to a memory clinic with SVD on MRI.

METHOD

We included 132 memory clinic patients (mean age 73 ± 10, 56% male) with SVD on MRI. We excluded patients with large non-lacunar cortical infarcts. Global CBF (mL/min per 100 mL of brain tissue) was derived from 2-dimensional phase-contrast MRI focused on the internal carotid arteries and the basilar artery. SVD burden was defined as the sum of (each 1 point): white matter hyperintensities (WMHs) Fazekas 1 or more, lacunes, microbleeds (MBs), or enlarged perivascular spaces (PVS) presence, and each SVD feature separately. Linear regression analyses were performed to study the association between CBF and SVD burden, age- and sex-adjusted.

RESULTS

Median SVD burden score was 2, 36.4% of patients had MBs, 35.6% lacunar infarcts, 48.4% intermediate to severe enlarged PVS, and 57.6% a WMH Fazekas score 2 or more. Median WMH volume was 21.4 mL (25% quartile: 9.6 mL, 75% quartile: 32.5 mL). Mean CBF ± SD was 44.0 ± 11.9 mL/min per 100 mL brain. There was no relation between CBF and overall SVD burden (CBF difference per burden score point [95% CI]: -0.5 [-2.4; 1.4] mL/min/100 mL brain, p = 0.9). CBF did also not differ according to presence or absence or an high burden of any of the individual SVD features. Moreover, there was no significant relation between WMH volume and CBF (CBF difference per ml increase in WMH [95% CI] -0.6 [-1.5; 0.3] mL/min/100 mL brain p = 0.2).

CONCLUSION

Global CBF was not related to overall SVD burden or with individual SVD features in this memory clinic cohort, indicating that in this setting these lesions were not primarily due to cerebral hypoperfusion.

[Clinico-radiological spectrum of cerebral small vessel diseases]

Cerebral small vessel diseases are frequent and can be seen through all ages. Although the most frequent forms related to age and hypertension or to cerebral amyloid angiopathy are mainly observed in subjects over 50 years of age, rarer forms may affect young people, sometimes even children. Some familial or inflammatory forms can be particularly misleading with some presentations very difficult to relate to a microvascular origin. Cerebral small vessel diseases thus raise both daily therapeutic issues and much rarer diagnostic questions, sometimes extremely complex. Our aim was to review the main clinical initial presentations and the clinico-radiological spectrum of associated underlying conditions.

Association of Circadian Rhythm of Blood Pressure and Cerebral Small Vessel Disease in Community-Based Elderly Population

BACKGROUND

Although it is accepted that the etiology of cerebral small vessel disease (CSVD) is associated with cardiovascular risk factors, the association between CSVD and the circadian rhythm of blood pressure (BP) is unclear. We aimed to determine if such an association existed in the elderly population.

METHOD

White matter hyperintensities (WMHs), lacunes, microbleeds, nocturnal dipping pattern (NDP), and morning surge in systolic blood pressure (SBP) were assessed in 2,091 participants ≥60 years of age.

RESULTS

During an average of 63 months of follow-up, WMH and the WMH-to-intracranial volume ratio were significantly increased in extreme dippers, nondippers, and reverse dippers than those in dippers (p < .001). For new-incident Fazekas scale ≥2, the hazard ratios were 1.77 (95% confidence interval [CI], 1.09-2.86) for extreme dippers, 2.20 (95% CI, 1.48-3.28) for nondippers, and 2.43 (95% CI, 1.59-3.70) for reverse dippers compared with dippers, and 1.04 (95% CI, 0.81-1.35) for higher morning surge compared with lower morning surge. Nondippers and reverse dippers were associated with higher risks of new-incident lacunes and microbleeds than dippers (p < .05). Higher morning surge was associated with a higher risk of new-incident microbleeds than lower morning surge (p < .05).

CONCLUSION

NDPs in SBP played an important role in CSVD, and the morning surge in SBP was associated with cerebral microbleeds in community-based elderly population beyond the average SBP level.

High triglyceride-glucose index is associated with subclinical cerebral small vessel disease in a healthy population: a cross-sectional study

Background

The triglyceride-glucose (TyG) index is a marker of insulin resistance (IR) and has been associated with various metabolic syndromes, cardiovascular diseases, and cerebrovascular diseases. However, limited information is available regarding its association with subclinical cerebral small vessel disease (cSVD). In this study, we evaluated the relationship between the TyG index and cSVD, including silent brain infarcts (SBIs) and white matter hyperintensity (WMH).

Methods

We assessed health check-up participants aged 40–79 years from 2006 to 2013. The TyG index was calculated using the log scale of fasting triglyceride (mg/dL) × fasting glucose (mg/dL)/2. The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was also calculated. This was compared with two insulin surrogates and cSVD as another IR indicator and compared the association between two insulin surrogates and cSVD. SBI was measured for both prevalence and burden. The WMH volume was quantitatively rated using a computer-assisted semi-automated technique.

Results

A total of 2615 participants were evaluated (median age: 56 years, male sex: 53%). In the multivariable logistic regression analysis, the TyG index was seen to be associated with SBI prevalence (adjusted odds ratio: 1.39; 95% confidence interval [CI] = 1.06–1.81). Further quantitative analyses showed a positive dose–response relationship between the TyG index and SBI burden (P for trend = 0.006). In multivariable linear regression analysis, the TyG index was also found to be related to the volume of WMH (β = 0.084; 95% CI = 0.013 to 0.154). Additionally, the TyG index showed a similar or slightly stronger association with the prevalence of SBI and the volume of WMH than did HOMA-IR.

Conclusions

A high TyG index was associated with a higher prevalence and burden of cSVD in a neurologically healthy population. This marker of IR could be a convenient and useful predictor of cSVD.

Imaging of the aging brain and development of MRI signal abnormalities

Major changes occur at the cerebral level with aging. Cerebral atrophy develops progressively. Multiple lesions related to small-vessel diseases are detected in association with cerebral atrophy including white-matter hyperintensities, lacunes, microbleeds, dilated perivascular spaces and cerebral, including cortex, atrophy. The clinical impact and predictive value of these Imaging makers were examined.

Isolated, Subtle Neurological Abnormalities in Mild Cognitive Impairment Types

BACKGROUND

Isolated, subtle neurological abnormalities (ISNA) are commonly seen in aging and have been related to cerebral small vessel disease (SVD) and subcortical atrophy in neurologically and cognitively healthy aging subjects.

OBJECTIVE

To investigate the frequency of ISNA in different mild cognitive impairment (MCI) types and to evaluate for each MCI type, the cross-sectional relation between ISNA and white matter hyperintensities (WMH), lacunes, caudate atrophy, and ventricular enlargement.

METHODS

One thousand two hundred fifty subjects with different MCI types were included in the analysis and underwent brain magnetic resonance imaging. WMHs were assessed through two visual rating scales. Lacunes were also rated. Atrophy of the caudate nuclei and ventricular enlargement were assessed through the bicaudate ratio (BCr) and the lateral ventricles to brain ratio (LVBr), respectively. Apolipoprotein E (APOE) genotypes were also assessed. The routine neurological examination was used to evaluate ISNAs that were clustered as central-based signs, cerebellar-based signs, and primitive reflexes. The items of Part-III of the Unified Parkinson's Disease Rating Scale were used to evaluate ISNAs that were clustered as mild parkinsonian signs. Associations of ISNAs with imaging findings were determined through logistic regression analysis.

RESULTS

The ISNAs increase with the age and are present in all MCI types, particularly in those multiple domains, and carrying the APOE ϵ4 allele, and are associated with WMH, lacunes, BCr, and LVBr.

CONCLUSION

This study demonstrates that cortical and subcortical vascular and atrophic processes contribute to ISNAs. Long prospective population-based studies are needed to disentangle the role of ISNAs in the conversion from MCI to dementia.

Inflammation and cerebral small vessel disease: A systematic review

Inflammation is increasingly implicated as a risk factor for dementia, stroke, and small vessel disease (SVD). However, the underlying mechanisms and causative pathways remain unclear. We systematically reviewed the existing literature on the associations between markers of inflammation and SVD (i.e., white matter hyperintensities (WMH), lacunes, enlarged perivascular spaces (EPVS), cerebral microbleeds (CMB)) in cohorts of older people with good health, cerebrovascular disease, or cognitive impairment. Based on distinctions made in the literature, markers of inflammation were classified as systemic inflammation (e.g. C-reactive protein, interleukin-6, fibrinogen) or vascular inflammation/endothelial dysfunction (e.g. homocysteine, von Willebrand factor, Lp-PLA2). Evidence from 82 articles revealed relatively robust associations between SVD and markers of vascular inflammation, especially amongst stroke patients, suggesting that alterations to the endothelium and blood-brain barrier may be a driving force behind SVD. Conversely, cross-sectional findings on systemic inflammation were mixed, although longitudinal investigations demonstrated that elevated levels of systemic inflammatory markers at baseline predicted subsequent SVD severity and progression. Importantly, regional analysis revealed that systemic and vascular inflammation were differentially related to two distinct forms of SVD. Specifically, markers of vascular inflammation tended to be associated with SVD in areas typical of hypertensive arteriopathy (e.g., basal ganglia), while systemic inflammation appeared to be involved in CAA-related vascular damage (e.g., centrum semiovale). Nonetheless, there is insufficient data to establish whether inflammation is causal of, or secondary to, SVD. Findings have important implications on interventions, suggesting the potential utility of treatments targeting the brain endothelium and blood brain barrier to combat SVD and associated neurodegenerative diseases.

Nociceptive Primitive Reflexes in Neurologically and Cognitively Healthy Aging Subjects

BACKGROUND

To assess the prevalence of three nociceptive primitive reflexes (nPR), i.e., glabellar tap, snout reflex, and palmomental reflex, in neurologically and cognitively healthy (NCH) aging subjects.

OBJECTIVE

To investigate whether nPR are cross-sectionally associated with white matter hyperintensities (WMH), lacunes, atrophy of the caudate nuclei, and global brain atrophy.

METHODS

A total of 1246 NCH subjects aged 45-91 years were included in the study and underwent standard brain MRI. Atrophy of the caudate nuclei and global brain atrophy were assessed through the bicaudate ratio (BCr) and lateral ventricles to brain ratio (LVBr), respectively. WMH were assessed through visual rating scales. Lacunes were also rated. Association of nPR with vascular risk factors/diseases and imaging findings was evaluated using logistic regression analysis.

RESULTS

nPR were exhibited by 33.1% of subjects and increased with age. Subjects with nPR performed less than subjects without nPR in tests evaluating global cognition, executive functions, attention, and language. Snout reflex was the most common nPR, followed by glabellar tap and palmomental reflex. Glabellar tap was associated with parieto-temporal WMH, BCr, and LVBr; snout reflex was associated with frontal lacunes, temporal WMH, BCr, and LVBr; palmomental reflex was associated with parieto-occipital WMH, basal ganglia lacunes, BCr, and LVBr.

CONCLUSIONS

This study demonstrates that in NCH aging individuals, nPR are associated with WMH, lacunes, BCr, and LVBr and are probably a warning sign of incipient cognitive decline. Therefore, NCH subjects presenting nPR should manage their vascular risk factors/vascular diseases rigorously in order to prevent or delay progression of small vessel disease, and future neurological and cognitive disabilities.

Free water determines diffusion alterations and clinical status in cerebral small vessel disease

INTRODUCTION

Diffusion tensor imaging detects early tissue alterations in Alzheimer's disease and cerebral small vessel disease (SVD). However, the origin of diffusion alterations in SVD is largely unknown.

METHODS

To gain further insight, we applied free water (FW) imaging to patients with genetically defined SVD (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy [CADASIL], n = 57), sporadic SVD (n = 444), and healthy controls (n = 28). We modeled freely diffusing water in the extracellular space (FW) and measures reflecting fiber structure (tissue compartment). We tested associations between these measures and clinical status (processing speed and disability).

RESULTS

Diffusion alterations in SVD were mostly driven by increased FW and less by tissue compartment alterations. Among imaging markers, FW showed the strongest association with clinical status (R2 up to 34%, P < .0001). Findings were consistent across patients with CADASIL and sporadic SVD.

DISCUSSION

Diffusion alterations and clinical status in SVD are largely determined by extracellular fluid increase rather than alterations of white matter fiber organization.

Cerebral small vessel disease and risk of incident stroke, dementia and depression, and all-cause mortality: A systematic review and meta-analysis

MRI features of cerebral small vessel disease (CSVD), i.e. white matter hyperintensities, lacunes, microbleeds, perivascular spaces, and cerebral atrophy, may be associated with clinical events, but the strength of these associations remains unclear. We conducted a systematic review and meta-analysis on the association between these features and incident ischaemic and haemorrhagic stroke, all-cause dementia and depression, and all-cause mortality. For the association with stroke, 36 studies were identified (number of individuals/events [n] = 38,432/4,136), for dementia 28 (n = 16,458/1,709), for depression nine (n = 9,538/1,746), and for mortality 28 (n = 23,031/2,558). Only two studies evaluated perivascular spaces; these results were not pooled. Pooled analyses showed that all other features were associated with all outcomes (hazard ratios ranged 1.22–2.72). Combinations of two features were more strongly associated with stroke than any individual feature. Individual features and combinations of CSVD features are strongly associated with incident ischaemic and haemorrhagic stroke, all-cause dementia and depression, and all-cause mortality. If these associations are causal, the strength of these associations suggests that a substantial burden of disease is attributable to CSVD.

Microbleeds are associated with depressive symptoms in Alzheimer's disease

INTRODUCTION

Co-occurrence of cerebrovascular disease and depression led to the "vascular depression hypothesis". White matter hyperintensities (WMHs) have been associated with depressive symptoms in population-based studies. We studied the association between small vessel disease and depressive symptoms in a memory clinic population.

METHODS

We included >2000 patients with subjective cognitive decline (SCD), mild cognitive impairment, and Alzheimer's disease (AD). Magnetic resonance imaging was rated for WMHs, lacunes, and microbleeds. Depressive symptoms were assessed using the Geriatric Depression Scale. We performed logistic regression analysis.

RESULTS

Depressive symptoms were present in AD: 17%; mild cognitive impairment: 25%; and SCD: 23%. SCD patients with WMHs showed higher propensity of depressive symptoms than AD patients with WMHs. AD patients with microbleeds were more likely to have depressive symptoms compared with AD patients without microbleeds (odds ratio = 1.70; 95% confidence interval: 1.08-2.68).

DISCUSSION

Microbleeds are associated with depressive symptoms in AD, supporting a potential role of cerebral amyloid angiopathy in the occurrence of depressive symptoms in AD.

Advanced Neuroimaging of Cerebral Small Vessel Disease

Cerebral small vessel disease (SVD) is characterised by damage to deep grey and white matter structures of the brain and is responsible for a diverse range of clinical problems that include stroke and dementia. In this review, we describe advances in neuroimaging published since January 2015, mainly with magnetic resonance imaging (MRI), that, in general, are improving quantification, observation and investigation of SVD focussing on three areas: quantifying the total SVD burden, imaging brain microstructural integrity and imaging vascular malfunction. Methods to capture ‘whole brain SVD burden’ across the spectrum of SVD imaging changes will be useful for patient stratification in clinical trials, an approach that we are already testing. More sophisticated imaging measures of SVD microstructural damage are allowing the disease to be studied at earlier stages, will help identify specific factors that are important in development of overt SVD imaging features and in understanding why specific clinical consequences may occur. Imaging vascular function will help establish the precise blood vessel and blood flow alterations at early disease stages and, together with microstructural integrity measures, may provide important surrogate endpoints in clinical trials testing new interventions. Better knowledge of SVD pathophysiology will help identify new treatment targets, improve patient stratification and may in future increase efficiency of clinical trials through smaller sample sizes or shorter follow-up periods. However, most of these methods are not yet sufficiently mature to use with confidence in clinical trials, although rapid advances in the field suggest that reliable quantification of SVD lesion burden, tissue microstructural integrity and vascular dysfunction are imminent.

Deep multi-scale location-aware 3D convolutional neural networks for automated detection of lacunes of presumed vascular origin

Lacunes of presumed vascular origin (lacunes) are associated with an increased risk of stroke, gait impairment, and dementia and are a primary imaging feature of the small vessel disease. Quantification of lacunes may be of great importance to elucidate the mechanisms behind neuro-degenerative disorders and is recommended as part of study standards for small vessel disease research. However, due to the different appearance of lacunes in various brain regions and the existence of other similar-looking structures, such as perivascular spaces, manual annotation is a difficult, elaborative and subjective task, which can potentially be greatly improved by reliable and consistent computer-aided detection (CAD) routines. In this paper, we propose an automated two-stage method using deep convolutional neural networks (CNN). We show that this method has good performance and can considerably benefit readers. We first use a fully convolutional neural network to detect initial candidates. In the second step, we employ a 3D CNN as a false positive reduction tool. As the location information is important to the analysis of candidate structures, we further equip the network with contextual information using multi-scale analysis and integration of explicit location features. We trained, validated and tested our networks on a large dataset of 1075 cases obtained from two different studies. Subsequently, we conducted an observer study with four trained observers and compared our method with them using a free-response operating characteristic analysis. Shown on a test set of 111 cases, the resulting CAD system exhibits performance similar to the trained human observers and achieves a sensitivity of 0.974 with 0.13 false positives per slice. A feasibility study also showed that a trained human observer would considerably benefit once aided by the CAD system.

Elevated blood viscosity is associated with cerebral small vessel disease in patients with acute ischemic stroke

BACKGROUND

Increased level of blood viscosity, which is one of the major factors that determine blood rheology, has been reported as a risk factor or predictor for cerebrovascular events. We investigated how blood viscosity is associated with acute stroke and chronic radiological manifestations of cerebral small vessel disease, and how blood viscosity changes after stroke.

METHODS

We prospectively enrolled consecutive patients with acute ischemic stroke. Whole blood viscosities at a low or high shear rate were measured using a scanning capillary tube viscometer, and were referred to as diastolic blood viscosity (DBV) and systolic blood viscosity (SBV), respectively. Correlations between blood viscosity and acute stroke etiology or chronic radiological manifestations of cerebral small vessel disease were investigated. The temporal profiles of blood viscosity at the onset of stroke and follow-up at 1 and 5 weeks were investigated.

RESULTS

Of the 127 patients admitted with acute ischemic stroke, 63 patients were included in the final analyses. DBV at the onset of stroke was significantly higher in small artery occlusion (SAO) stroke than in other stroke subtypes (p = 0.037). DBV showed a significant positive correlation with the number of chronic lacunes (r = 0.274, p = 0.030). The temporal profiles of DBV in SAO stroke showed a transient decrease due to the hydration therapy after 1 week and recurrent elevation at 5 week follow-up (p = 0.009).

CONCLUSIONS

Our study suggests that elevated DBV may play a role in the development of acute and chronic manifestations of cerebral small vessel disease. The recurring elevation of DBV in SAO stroke indicates that sufficient hydration and additional therapeutic interventions targeting blood viscosity may be needed in patients with SAO stroke.

What is the relationship between type 2 diabetes mellitus status and the neuroradiological correlates of cerebral small vessel disease in adults? Protocol for a systematic review

BACKGROUND

Cerebral small vessel disease (CSVD) is a common cause of stroke, dementia, and functional decline. In recent years, neuroradiologic correlates of CSVD have been identified. These imaging findings, best characterized on magnetic resonance imaging (MRI), include some combination of white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, and cerebral atrophy. Though some cohorts have reported that participants with type 2 diabetes mellitus (T2DM), an important risk factor for CSVD, may have a distinct neuroradiologic phenotype, this relationship is not well-characterized. Adults with diabetes mellitus have a two- to threefold higher incidence of ischemic stroke compared to controls and are an increasingly important population given global trends of increasing diabetes prevalence. This study aims to determine if adults with CSVD and T2DM have a distinct neuroradiologic phenotype.

METHODS

A systematic search of the literature will be conducted to find articles that report the MRI features of CSVD in a cohort of participants including those with and without type 2 diabetes mellitus (T2DM). A number of databases will be searched including MEDLINE, Embase, CINAHL, and Web of Science. Proceedings and abstracts from key conferences will also be reviewed and relevant journals hand searched for additional papers. The references from selected papers will be scanned. Screening of potential articles, data extraction, and quality appraisal will be performed in duplicate by independent reviewers. Odds ratios and 95% confidence intervals for the presence versus absence of each neuroradiologic correlate of interest from each included study will be calculated. If sufficient homogeneity exists among studies, a meta-analysis will be performed for each neuroradiologic correlate of CSVD. If heterogeneity of studies precludes data pooling, results will be presented in narrative form.

DISCUSSION

Determining whether a distinct neuroradiologic phenotype of CSVD exists in adults with T2DM will provide insight into the underlying mechanisms of CSVD and guide future research on therapeutic targets.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016046669.

[Not Available]

Zusammenfassung. Zerebrale Mikroangiopathien umfassen eine Gruppe neuropathologischer Prozesse, die die kleinen Perforationsarterien, Arteriolen und Kapillaren beeinflussen. Neuroimaging-Merkmale der Einengung der kleinen Koronararterienäste (Small Vessel Disease) sind ischämische und hämorrhagische Marker: jüngster kleiner subkortikaler Infarkt, Lakune vermuteten vaskulären Ursprungs, Hyperintensität der weissen Masse, perivaskuläre Räume, zerebrale Mikroblutungen, Hirnatrophie, kortikale oberflächliche Siderose und akute subarachnoidale Blutungen. Diese Läsionen gelten als der Hauptrisikofaktor der vaskulären kognitiven Störungen. Die zerebrale Mikroangiopathie wird typischerweise in zwei Hauptformen kategorisiert: die nicht-amyloide Angiopathie, die auch als «hypertensive Arteriopathie» bezeichnet wird, die oft mit fortgeschrittenem Alter und vaskulären Risikofaktoren und der zerebralen Amyloidangiopathie zusammenhängt. Die zerebrale Amyloidangiopathie ist klinisch charakterisiert durch kognitive Beeinträchtigungen, intrazerebrale Blutungen und durch transiente Episoden fokal-neurologischer Defizite aufgrund von Subarachnoidalblutungen.

Total MRI load of cerebral small vessel disease and cognitive ability in older people

Cerebral small vessel disease (SVD) may cause cognitive dysfunction. We tested the association between the combined presence of magnetic resonance imaging (MRI) features of SVD and cognitive ability in older age. Cognitive testing and brain MRI were performed in 680 older participants. MRI presence of lacunes, white matter hyperintensities, microbleeds, and perivascular spaces were summed in a score of 0-4 representing all SVD features combined. We also applied latent variable modeling to test whether the 4 MRI features form a unitary SVD construct. The SVD score showed significant associations with general cognitive ability. Latent variable modeling indicated that the 4 MRI markers formed a unitary construct, which showed consistent associations with cognitive ability compared with the SVD score. Total MRI load of SVD is associated with lower general cognitive ability in older age. The total SVD score performed consistently with the more complex latent variable model, suggesting validity and potential utility in future research for determining total SVD load.

Strategic lacunes and their relationship to cognitive impairment in cerebral small vessel disease

Objectives

Lacunes are an important disease feature of cerebral small vessel disease (SVD) but their relationship to cognitive impairment is not fully understood. To investigate this we determined (1) the relationship between lacune count and total lacune volume with cognition, (2) the spatial distribution of lacunes and the cognitive impact of lacune location, and (3) the whole brain anatomical covariance associated with these strategically located regions of lacune damage.

Methods

One hundred and twenty one patients with symptomatic lacunar stroke and radiological leukoaraiosis were recruited and multimodal MRI and neuropsychological data acquired. Lacunes were mapped semi-automatically and their volume calculated. Lacune location was automatically determined by projection onto atlases, including an atlas which segments the thalamus based on its connectivity to the cortex. Lacune locations were correlated with neuropsychological results. Voxel based morphometry was used to create anatomical covariance maps for these ‘strategic’ regions.

Results

Lacune number and lacune volume were positively associated with worse executive function (number p < 0.001; volume p < 0.001) and processing speed (number p < 0.001; volume p < 0.001). Thalamic lacunes, particularly those in regions with connectivity to the prefrontal cortex, were associated with impaired processing speed (Bonferroni corrected p = 0.016). Regions of associated anatomical covariance included the medial prefrontal, orbitofrontal, anterior insular cortex and the striatum.

Conclusion

Lacunes are important predictors of cognitive impairment in SVD. We highlight the importance of spatial distribution, particularly of anteromedial thalamic lacunes which are associated with impaired information processing speed and may mediate cognitive impairment via disruption of connectivity to the prefrontal cortex.

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Lacunes are a predictor of cognitive impairment in cerebral small vessel disease

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Lacunes in the anteromedial thalamus are associated with impaired processing speed

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This region was identified to have connectivity to the prefrontal cortex

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We validate this finding with the help of a structural covariance analysis

Dysglycemia, brain volume and vascular lesions on MRI in a memory clinic population

OBJECTIVE

It is unclear, if the association between abnormalities in glucose metabolism (dysglycemia) and impaired cognitive functioning is primarily driven by degenerative or vascular brain damage. We therefore examined the relation between dysglycemia and brain volume and vascular lesions on MRI in a memory clinic population.

METHODS

The relations between markers of glycemia (HbA1c and fasting glucose levels) and normalized brain volume, medial temporal lobe atrophy and vascular lesions (white matter hyperintensities, lacunes) were assessed in 274 consecutive patients attending a memory clinic, using linear regression analyses.

RESULTS

Clinical diagnoses were subjective complaints (n=117), mild cognitive impairment (n=62), Alzheimer's disease (n=61) and other type of dementia (n=34). Twenty patients had a history of diabetes. Across the whole study population there was no relation between HbA1c or fasting glucose and the brain MRI measurements, after adjustments for age, sex and diagnostic group. Secondary analyses after stratification by diabetes status, diagnosis and median age (67 years) did not change the results.

CONCLUSION

In this memory clinic population, dysglycemia was not associated with either brain volume or vascular lesions. Apparently, dysglycemia is not associated with a specific class of brain pathology in patients with cognitive complaints.

Small vessel disease and subcortical vascular dementia

Atherothromboembolism and intracranial small vessel disease are considered to be the main causes of cerebrovascular injury, which may lead to cognitive impairment and vascular dementia (VaD). VaD appears to be the second most common type of dementia with prevalence estimates of 10-15%. Cortical or multi-infarct dementia and subcortical vascular dementia (SVD) are suggested to be the two main forms of VaD. The main clinical features of SVD comprise decreased motor performance, early impairment of attention and executive function with slowing of information processing. SVD results from lacunar infarcts or multiple microinfarcts in the basal ganglia, thalamus, brainstem and white matter and are associated with more than 50% of the VaD cases. White matter changes including regions of incomplete infarction are usually widespread in VaD but their contribution to impairment of subcortical regions is unclear. While most of VaD occurs sporadically only a small proportion of cases bear clear familial traits. CADASIL is likely the most common form of hereditary VaD, which arises from subcortical arteriopathy. SVD needs unambiguous definition to impact on preventative and treatment strategies, and critical for selective recruitment to clinical trials.