Silent brain infarcts: a systematic review

Risk of recurrent stroke in patients with silent brain infarction in the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) imaging substudy

BACKGROUND AND PURPOSE

Silent brain infarctions are associated with an increased risk of stroke in healthy individuals. Risk of recurrent stroke in patients with both symptomatic and silent brain infarction (SBI) has only been investigated in patients with cardioembolic stroke in the European Atrial Fibrillation Trial. We assessed whether patients with recent noncardioembolic stroke and SBI detected on MRI are at increased risk for recurrent stroke, other cardiovascular events, and mortality.

METHODS

The prevalence of SBI detected on MRI was assessed in 1014 patients enrolled in the imaging substudy of the Prevention Regimen for Effectively Avoiding Second Strokes (PRoFESS) trial. The primary outcome was first recurrence of stroke in patients with both symptomatic stroke and SBI in comparison with age- and sex-matched patients with stroke without SBI. Secondary outcomes were a combined vascular end point, other vascular events, and mortality. The 2 groups were compared using conditional logistic regression.

RESULTS

Silent brain infarction was detected in 207 (20.4%) of the 1014 patients. Twenty-seven (13.0%) patients with SBI and 19 (9.2%) without SBI had a recurrent stroke (OR, 1.42; 95% CI, 0.79-2.56; P=0.24) during a mean follow-up of 2.5 years. Similarly, there was no statistically significant difference for all secondary outcome parameters between patients with SBI and matched patients without SBI.

CONCLUSIONS

The presence of SBI in patients with recent mild noncardioembolic ischemic stroke could not be shown to be an independent risk factor for recurrent stroke, other vascular events, or a higher mortality rate.

CLINICAL TRIAL REGISTRATION

URL: http://clinicaltrials.gov. Unique identifier: NCT00153062.

The VAS-COG clinic: an out-patient service for patients with cognitive and behavioral consequences of cerebrovascular diseases

Services dedicated to patients with cognitive and behavioral consequences of cerebrovascular diseases (CVD) are not established. We started an out-patient clinic (the "VAS-COG clinic") to assess patients with psycho-cognitive disturbances related to CVD. The work-up includes a clinical-neuroimaging diagnostic process and the individuation of the best therapeutic strategies as done in patients with neurodegenerative cognitive impairment. We report the results of the first 5 years of activity. Reasons for patient referral were not only cognitive, language, gait, and psychiatric disturbances related to stroke or chronic CVD, but also neuroimaging evidence of vascular encephalopathy and screening for familial microangiopathies. The patients were evaluated with uniformed protocols. From January 2006 to November 2010, we evaluated 403 patients. Of these, 374 (93%; mean age 69.7 years ± 15.0) were considered appropriate for the VAS-COG clinic. The following diagnoses were made: vascular dementia (8.6%), Alzheimer disease (2.1%), mixed dementia (vascular plus degenerative) (4.8%), vascular mild cognitive impairment (MCI) (9.1%), amnesic-MCI (8.0%), mixed-MCI (4.8%), post-stroke depression (2.7%), post-stroke language disturbances (4.5%), subjective memory complaint (1.3%), familiar microangiopathy (31.3%), vascular encephalopathy evidenced by neuroimaging not associated with specific clinical disturbances (15.3%), and other conditions (7.5%). Psycho-cognitive disturbances associated with CVD are heterogeneous. In addition to acute stroke care strategies, long-term assessment of patients with CVD is required. The VAS-COG clinic may represent a model in this regard and might be important for improving the care of patients and offering counseling to their families. The efficacy of this service needs, however, to be proved by successive work.

Silent brain infarction in the presence of systemic vascular disease

Objective

To determine the prevalence of asymptomatic brain ischaemic in the presence of vascular disease in other arterial territories.

Design

Studies up to January 2011 were identified through comprehensive search strategies. Arcsine transformation for meta-analysis was used to calculate the standardized mean difference (SMD) and 95% confidence intervals (CI).

Setting

A systematic review and meta-analysis were performed.

Participants

For each study, the proportion of patients positive for SBI in the presence of other systemic vascular disease was extracted and analyzed.

Main outcome measures

Using a random-effects model, a pooled effect estimate interpreted as a percentage prevalence of disease was calculated.

Results

SBI in the presence of acute ischaemic stroke was found in 23% (SMD 0.99; P < 0.001; 95% CI 0.88–1.10); a 35% prevalence was found in patients with coronary artery disease (SMD 1.26; P < 0.001; 95% CI 0.95–1.58); and a 14% prevalence in patients with peripheral artery disease (SMD 0.48; P < 0.002; 95% CI 0.42–0.54), although the data-set in the latter is smaller.

Conclusions

Patients with systemic vascular disease are at an increased risk of silent brain infarction.

Characteristics of MR infarcts associated with dementia and cognitive function in the elderly

BACKGROUND

Little information exists on the simultaneous effects of magnetic resonance (MR) infarct characteristics, that may increase the likelihood of dementia or lower cognitive function in community populations.

METHODS

Participants were 580 community-dwelling individuals from the Chicago Health and Aging Project (CHAP) who underwent detailed clinical evaluation and MR imaging. The association of MR infarct characteristics (region, number, side, and size) with dementia, global cognition and cognition in five separate cognitive domains was examined using logistic and linear regression analyses controlling for age, sex, race, education and time elapsed between clinical evaluation and MRI.

RESULTS

A total of 156 persons had MR infarcts: 108 with 1 infarct and 48 with multiple. Poorer cognitive function and, in particular, slower perceptual speed, were associated with infarcts characterized as cortical, multiple, bilateral or large (all p < 0.05). Multiple infarcts in multiple regions were associated with poor performance in all cognitive domains except visuospatial ability (p < 0.05). Race did not modify any of these associations.

CONCLUSIONS

In this community sample, cortical and multiple infarcts in multiple regions were associated with dementia; cortical, multiple, large and bilateral infarcts were associated with lower cognition, particularly lower memory function and perceptual speed. These effects were not modified by race.

Depression, strokes and dementia: new biological insights into an unfortunate pathway

The literature emphasizes the risk of depression after a stroke. Less well known is the fact that depression may be as big a risk factor for strokes as hypertension, particularly in the older age group. This article reviews the risk for stroke and cognitive impairment consequent to depression, and describes the cardiovascular and immunological mechanisms that would appear to link depression to its cerebrovascular consequences. As well, the article refers to the brain imaging signatures that may allow prediction of impending brain injury. Finally, some questions that might be explored by future research are suggested, and some practical means to identify and help those at risk for the development of depression-associated vascular disease of the brain are suggested.

Risk factors for lacune subtypes in the Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Lacunar infarctions are mainly due to 2 microvascular pathologies: lipohyalinosis and microatheroma. Little is known about risk factor differences for these subtypes. We hypothesized that diabetes and glycated hemoglobin (HbA(1)c) would be related preferentially to the lipohyalinotic subtype.

METHODS

We performed a cross-section analysis of the brain MRI data from 1,827 participants in the Atherosclerosis Risk in Communities study. We divided subcortical lesions ≤ 20 mm in diameter into those ≤ 7 mm (of probable lipohyalinotic etiology) and 8-20 mm (probably due to microatheroma) and used Poisson regression to investigate associations with the number of each type of lesion. Unlike previous studies, we also fitted a model involving lesions <3 mm.

RESULTS

Age (prevalence ratio [PR] 1.11 per year; 95% confidence interval [CI] 1.08-1.14), black ethnicity (vs white, PR 1.66; 95% CI 1.27-2.16), hypertension (PR 2.12; 95% CI 1.61-2.79), diabetes (PR 1.42; 95% CI 1.08-1.87), and ever-smoking (PR 1.34; 95% CI 1.04-1.74) were significantly associated with lesions ≤ 7 mm. Findings were similar for lesions <3 mm. HbA(1)c, substituted for diabetes, was also associated with smaller lesions. Significantly associated with 8-20 mm lesions were age (PR 1.14; 95% CI 1.09-1.20), hypertension (PR 1.79; 95% CI 1.14-2.83), ever-smoking (PR 2.66; 95% CI 1.63-4.34), and low-density lipoprotein (LDL) cholesterol (PR 1.27 per SD; 95% CI 1.06-1.52). When we analyzed only participants with lesions, history of smoking (PR 1.99; 95% CI 1.23-3.20) and LDL (PR 1.33 per SD; 95% CI 1.08-1.65) were associated with lesions 8-20 mm.

CONCLUSIONS

Smaller lacunes (even those <3 mm) were associated with diabetes and HbA(1)c, and larger lacunes associated with LDL cholesterol, differences which support long-held theories relating to their underlying pathology. The findings may contribute to broader understanding of cerebral microvascular disease.

Cerebral small vessel disease: a review of clinical, radiological, and histopathological phenotypes

Cerebral small vessel disease is difficult to directly visualize in vivo. Therefore, we rely on radiological phenotypes as surrogate markers of disease. The principal phenotypes of clinical interest are small, deep brain infarcts, cerebral white matter lesions, deep brain haemorrhages, and cerebral microbleeds. The causes or mechanisms underlying these phenotypes are understood in varying degrees of detail. This review aims to summarize recent knowledge regarding these phenotypes and place it in context with classical clinicopathological observations to provide mechanistic, clinical, and therapeutic insights into small vessel disease.

Frequent and widespread vascular abnormalities in human signal transducer and activator of transcription 3 deficiency

BACKGROUND

Signal transducer and activator of transcription 3 (STAT3) deficiency is responsible for autosomal dominant hyperimmunoglobulin E syndrome, characterized by recurrent bacterial and fungal infections, connective tissue abnormalities, hyperimmunoglobulin E, and Th17 lymphopenia. Although vascular abnormalities have been reported in some patients, the prevalence, characteristics, and etiology of these features have yet to be described.

METHODS AND RESULTS

We prospectively screened 21 adult STAT3-deficient patients [corrected] (median age, 26 years; range, 17-44 years) [corrected] for vascular abnormalities. We explored the entire arterial vasculature with whole-body magnetic resonance imaging angiography, coronary multislice computed tomography, and echo-tracking-based imaging specifically for the [corrected] carotid arteries. We also assayed for serum biomarkers of inflammation and endothelial dysfunction. Finally, we studied murine models of aortic aneurysm in the presence and absence of inhibitors of STAT3-dependent signaling. Ninety-five percent of patients showed brain abnormalities (white matter hyperintensities, lacunar lesions suggestive of ischemic infarcts, and atrophy). We reported peripheral and brain artery abnormalities in 84% of the patients and detected coronary artery abnormalities in 50% of the patients. The most frequent vascular abnormalities were ectasia and aneurysm. The carotid intima-media thickness was markedly decreased, with a substantial increase in circumferential wall stress, indicating the occurrence of hypotrophic arterial remodeling in this STAT3-deficient population. Systemic inflammatory biomarker levels correlated poorly with the vascular phenotype. In vivo inhibition of STAT3 signaling or blockade of IL-17A resulted in a marked increase in aneurysm severity and fatal rupture in mouse models.

CONCLUSIONS

Vascular abnormalities are highly prevalent in patients with STAT3 deficiency. This feature is consistent with the greater susceptibility to vascular aneurysm observed after inhibition of STAT3-dependent signaling in mouse models.

Cerebral perfusion long term after therapeutic occlusion of the internal carotid artery in patients who tolerated angiographic balloon test occlusion

BACKGROUND AND PURPOSE

Therapeutic carotid occlusion is an established technique for treatment of large and giant aneurysms of the ICA, in patients with synchronous venous filling on angiography during BTO. Concern remains that hemodynamic alterations after permanent occlusion will predispose the patient to new ischemic injury in the ipsilateral hemisphere. The purpose of this study was to assess whether BTO with synchronous venous filling is associated with normal CBF long term after carotid sacrifice.

MATERIALS AND METHODS

Eleven patients were included (all women; mean age, 50.5 years; mean follow-up, 38.5 months). ASL with single and multiple TIs was used to assess CBF and its temporal characteristics. Selective ASL was used to assess actual territorial contribution of the ICA and BA. Collateral flow via the AcomA or PcomA or both was determined by time-resolved 3D PCMR. Paired t tests were used to compare CBF and timing parameters between hemispheres.

RESULTS

Absolute CBF values were within the normal range. There was no significant CBF difference between hemispheres ipsilateral and contralateral to carotid sacrifice (49.4 ± 11.2 versus 50.1 ± 10.1 mL/100 g/min). Arterial arrival time and trailing edge time were significantly prolonged on the occlusion side (816 ± 119 ms versus 741 ± 103 ms, P = .001; and 1765 ± 179 ms versus 1646 ± 190 ms, P < .001). Two patients had collateral flow through the AcomA only and were found to have increased timing parameters compared with 9 patients with mixed collateral flow through both the AcomA and PcomA.

CONCLUSIONS

In this small study, patients with synchronous venous filling during BTO had normal CBF long term after therapeutic ICA occlusion.

Does cerebral small vessel disease predict future decline of cognitive function in elderly people with type 2 diabetes?

AIMS

We conducted a 3-year longitudinal study concerning an association between cognitive function and cerebral small vessel disease (SVD) seen on magnetic resonance imaging (MRI) in elderly type 2 diabetic patients.

METHODS

Four cognitive function tests--MMSE, word recall, Digit Symbol Substitution (DSS), and Stroop Color Word (Stroop)--were performed in 67 diabetic patients twice in 2006 and 2009. SVD was diagnosed as silent brain infarct (SBI) and white matter lesions (WMLs) according to MRI.

RESULTS

Number of SBI was significantly correlated with a decline in DSS and Stroop tests, while WMLs grade was only associated with it in DSS tests after adjustment for age, gender, education years, the presence of hypertension and dyslipidemia, and smoking. Severity of SVD at baseline was stronger associated with cognitive function after the 3-year follow-up than at baseline. WMLs progression was associated with more rapid decline of DSS tests compared to a group without progression.

CONCLUSIONS

SVD seen on MRI is a good marker for predicting future cognitive decline, and monitoring of treatment through the use of such markers is expected to maintain a good quality of life for elderly diabetic patients.

Siblings with ischemic stroke study: results of a genome-wide scan for stroke loci

BACKGROUND AND PURPOSE

Ischemic stroke has a strong familial component to risk. The Siblings With Ischemic Stroke Study (SWISS) is a genome-wide, family-based analysis that included use of imputed genotypes. The Siblings With Ischemic Stroke Study was conducted to examine the associations between single-nucleotide polymorphisms (SNPs) and risk of stroke and stroke subtypes within pairs.

METHODS

The Siblings With Ischemic Stroke Study enrolled 312 probands with ischemic stroke from 70 US and Canadian centers. Affected siblings were ascertained by centers and confirmed by central record review; unaffected siblings were ascertained by telephone contact. Ischemic stroke was subtyped according to Trial of Org 10172 in Acute Stroke Treatment criteria. Genotyping was performed with an Illumina 610 quad array (probands) and an Illumina linkage V array (affected siblings). SNPs were imputed by using 1000 Genomes Project data and MACH software. Family-based association analyses were conducted by using the sibling transmission-disequilibrium test.

RESULTS

For all pairs, the correlation of age at stroke within pairs of affected siblings was r=0.83 (95% CI, 0.78-0.86; P<2.2×10(-16)). The correlation did not differ substantially by subtype. The concordance of stroke subtypes among affected pairs was 33.8% (kappa=0.13; P=5.06×10(-4)) and did not differ by age at stroke in the proband. Although no SNP achieved genome-wide significance for risk of ischemic stroke, there was clustering of the most associated SNPs on chromosomes 3p (neuronal nitric oxide synthase) and 6p.

CONCLUSIONS

Stroke subtype and age at stroke in affected sibling pairs exhibit significant clustering. No individual SNP reached genome-wide significance. However, 2 promising candidate loci were identified, including 1 that contains neuronal nitric oxide synthase, although these risk loci warrant further examination in larger sample collections.

Blood-brain barrier breakdown in acute and chronic cerebrovascular disease

Disruptions of the blood-brain barrier (BBB) and edema formation both play key roles in the development of neurological dysfunction in acute and chronic cerebral ischemia. Animal studies have revealed the molecular cascades that are initiated with hypoxia/ischemia in the cells forming the neurovascular unit and that contribute to cell death. Matrix metalloproteinases cause reversible degradation of tight junction proteins early after the onset of ischemia, and a delayed secondary opening during a neuroinflammatory response occurring from 24 to 72 hours after. Cyclooxygenases are important in the delayed opening as the neuroinflammatory response progresses. An early opening of the BBB within the 3-hour therapeutic window for tissue-type plasminogen activator can allow it to enter the brain and increase the risk of hemorrhage. Chronic hypoxic hypoperfusion opens the BBB, which contributes to the cognitive changes seen with lacunar strokes and white matter injury in subcortical ischemic vascular disease. This review will describe the molecular and cellular events associated with BBB disruption and potential therapies directed toward restoring the integrity of the neurovascular unit.

Genomic risk profiling of ischemic stroke: results of an international genome-wide association meta-analysis

INTRODUCTION

Familial aggregation of ischemic stroke derives from shared genetic and environmental factors. We present a meta-analysis of genome-wide association scans (GWAS) from 3 cohorts to identify the contribution of common variants to ischemic stroke risk.

METHODS

This study involved 1464 ischemic stroke cases and 1932 controls. Cases were genotyped using the Illumina 610 or 660 genotyping arrays; controls, with Illumina HumanHap 550Kv1 or 550Kv3 genotyping arrays. Imputation was performed with the 1000 Genomes European ancestry haplotypes (August 2010 release) as a reference. A total of 5,156,597 single-nucleotide polymorphisms (SNPs) were incorporated into the fixed effects meta-analysis. All SNPs associated with ischemic stroke (P<1×10(-5)) were incorporated into a multivariate risk profile model.

RESULTS

No SNP reached genome-wide significance for ischemic stroke (P<5×10(-8)). Secondary analysis identified a significant cumulative effect for age at onset of stroke (first versus fifth quintile of cumulative profiles based on SNPs associated with late onset, ß = 14.77 [10.85,18.68], P = 5.5×10(-12)), as well as a strong effect showing increased risk across samples with a high propensity for stroke among samples with enriched counts of suggestive risk alleles (P<5×10(-6)). Risk profile scores based only on genomic information offered little incremental prediction.

DISCUSSION

There is little evidence of a common genetic variant contributing to moderate risk of ischemic stroke. Quintiles based on genetic loading of alleles associated with a younger age at onset of ischemic stroke revealed a significant difference in age at onset between those in the upper and lower quintiles. Using common variants from GWAS and imputation, genomic profiling remains inferior to family history of stroke for defining risk. Inclusion of genomic (rare variant) information may be required to improve clinical risk profiling.

Silent cerebral events in asymptomatic carotid stenosis

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Protein-conjugated acrolein as a biochemical marker of brain infarction

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

Verbal memory performance and completion of cardiac rehabilitation in patients with coronary artery disease

OBJECTIVE

To assess cognitive performance as a predictor of noncompletion of cardiac rehabilitation (CR) using a standardized verbal memory test.

METHODS

This was a prospective cohort study of consecutive patients with coronary artery disease (n = 131) entering 1-year outpatient CR between April 2007 and May 2009. Verbal memory performance was assessed using the California Verbal Learning Test, Second Edition. Attendance at weekly CR sessions was recorded, and completion or noncompletion was determined according to comprehensive CR criteria. Depression was diagnosed according to DSM-IV criteria as a possible confounder.

RESULTS

Verbal memory performance at entry into CR differed significantly (F(1,130) = 7.80, p = .006) between noncompleters and completers (mean [SD] cumulative California Verbal Learning Test, Second Edition, score, -1.15 [2.59] versus 0.47 [3.12]) in analysis of covariance controlling for pertinent clinical confounders. Better verbal memory performance predicted a reduced risk of noncompletion (hazard ratio [HR] = 0.86, 95% confidence interval [CI] = 0.77-0.96, p = .009) in time-to-event analysis adjusted for depression (HR = 2.62, 95% CI = 1.33-5.17, p = .006) and smoking history (HR = 2.03, 95% CI = 0.98-4.22, p = .06). A post hoc analysis suggested that better verbal memory performance predicted a reduced risk of noncompletion for medical reasons (HR = 0.83, 95% CI = 0.70-0.99, p = .03).

CONCLUSIONS

Poorer verbal memory performance was associated with an increased risk of noncompletion of CR among participants with coronary artery disease. Further studies exploring practical methods for screening and targeted support might improve rehabilitation outcomes.

Cerebral small vessel disease and risk of death, ischemic stroke, and cardiac complications in patients with atherosclerotic disease: the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study

BACKGROUND AND PURPOSE

Cerebral small vessel disease may be related to vascular and nonvascular pathology. We assessed whether lacunar infarcts and white matter lesions on MRI increased the risk of vascular and nonvascular death and future vascular events in patients with atherosclerotic disease.

METHODS

Brain MRI was performed in 1309 patients with atherosclerotic disease from the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART-MR) study. Infarcts were scored visually and volumetric assessment of white matter lesion was performed. Patients were followed for a median of 4.5 years (range, 0.2 to 7.1 years) for death, ischemic stroke, and ischemic cardiac complications.

RESULTS

Cox regression models showed that presence of lacunar infarcts (n=229) increased the risk of vascular (hazard ratio, 2.6; 95% CI, 1.4 to 4.9) and nonvascular death (hazard ratio, 2.7; 95% CI, 1.3 to 5.3), adjusted for age, sex, vascular risk factors, nonlacunar infarcts, and white matter lesion. These risks were similar for patients with silent lacunar infarcts. White matter lesion volume (relative to total intracranial volume) increased the risk of vascular death (hazard ratio per milliliter increase, 1.03; 95% CI, 1.01 to 1.05) and white matter lesions in the upper quintile compared with lower quintiles increased risk of ischemic stroke (hazard ratio, 2.6; 95% CI, 1.3 to 4.9).

CONCLUSIONS

Cerebral small vessel disease, with or without a history of cerebrovascular disease, is associated with increased risk of death and ischemic stroke in patients with atherosclerotic disease.

Age-related white matter changes

Age-related white matter changes (WMC) are considered manifestation of arteriolosclerotic small vessel disease and are related to age and vascular risk factors. Most recent studies have shown that WMC are associated with a host of poor outcomes, including cognitive impairment, dementia, urinary incontinence, gait disturbances, depression, and increased risk of stroke and death. Although the clinical relevance of WMC has been extensively studied, to date, only very few clinical trials have evaluated potential symptomatic or preventive treatments for WMC. In this paper, we reviewed the current understanding in the pathophysiology, epidemiology, clinical importance, chemical biomarkers, and treatments of age-related WMC.

Vascular cognitive impairment: Current concepts and Indian perspective

Cognitive impairment due to cerebrovascular disease is termed “Vascular Cognitive Impairment” (VCI) and forms a spectrum that includes Vascular Dementia (VaD) and milder forms of cognitive impairment referred to as Vascular Mild Cognitive Impairment (VaMCI). VCI represents a complex neurological disorder that occurs as a result of interaction between vascular risk factors such as hypertension, diabetes, obesity, dyslipidemia, and brain parenchymal changes such as macro and micro infarcts, haemorrhages, white matter changes, and brain atrophy occurring in an ageing brain. Mixed degenerative and vascular pathologies are increasingly being recognised and an interaction between the AD pathology, vascular risk factors, and strokes is now proposed. The high cardiovascular disease burden in India, increasing stroke incidence, and ageing population have contributed to large numbers of patients with VCI in India. Inadequate resources coupled with low awareness make it a problem that needs urgent attention, it is important identify patients at early stages of cognitive impairment, to treat appropriately and prevent progression to frank dementia.

Integrating health into cognitive aging: toward a preventive cognitive neuroscience of aging

OBJECTIVES

We argue that age is a descriptive, and not explanatory, variable and consequently cannot account for the cognitive changes that often occur with aging. Once age is removed from consideration, other truly causal explanations for "cognitive aging" must be identified. We argue that health and disease represent an important class of explanatory variables for age-related cognitive changes.

METHODS/RESULTS

We make this argument first by reviewing the prevalence of risk factors, disability, and subclinical and frank disease in the elderly population. We emphasize that the complexity of health effects rivals that of age on cognition while noting that most studies of cognitive aging rarely consider this complexity fully. We then consider in more detail the "vascular hypothesis," which proposes that vascular diseases (e.g., stroke, heart disease) and their risk factors (e.g., hypertension) can explain aspects of cognitive decline in aging through their impact on circulatory and brain functions. Clinical implications of this hypothesis suggest that treatment of vascular risk factors might well reduce the incidence or severity of dementia syndromes.

DISCUSSION

We conclude with a brief summary of approaches to further integrate aspects of health and disease into the study of "cognitive aging."

Blood-brain barrier permeability abnormalities in vascular cognitive impairment

BACKGROUND AND PURPOSE

Disruption of the blood-brain barrier has been proposed to be important in vascular cognitive impairment. Increased cerebrospinal fluid albumin and contrast-enhanced MRI provide supporting evidence, but quantification of the blood-brain barrier permeability in patients with vascular cognitive impairment is lacking. Therefore, we acquired dynamic contrast-enhanced MRI to quantify blood-brain barrier permeability in vascular cognitive impairment. Method- We studied 60 patients with suspected vascular cognitive impairment. They had neurological and neuropsychological testing, permeability measurements with dynamic contrast-enhanced MRI, and lumbar puncture to measure albumin index. Patients were separated clinically into subcortical ischemic vascular disease (SIVD), multiple and lacunar infarcts, and leukoaraiosis. Twenty volunteers were controls for the dynamic contrast-enhanced MRI studies, and control cerebrospinal fluid was obtained from 20 individuals undergoing spinal anesthesia for nonneurological problems.

RESULTS

Thirty-six patients were classified as SIVD, 8 as multiple and lacunar infarcts, and 9 as leukoaraiosis. The albumin index was significantly increased in the SIVD group compared with 20 control subjects. Permeabilities for the patients with vascular cognitive impairment measured by dynamic contrast-enhanced MRI were significantly increased over control subjects (P<0.05). Patient age did not correlate with either the blood-brain barrier permeability or albumin index. Highest albumin index values were seen in the SIVD group (P<0.05) and were significantly increased over multiple and lacunar infarcts. K(i) values were elevated over control subjects in SIVD but were similar to multiple and lacunar infarcts.

CONCLUSIONS

There was abnormal permeability in white matter in patients with SIVD as shown by dynamic contrast-enhanced MRI and albumin index. Future studies will be needed to determine the relationship of blood-brain barrier damage and development of white matter hyperintensities.

Adults with late stage 3 chronic kidney disease are at high risk for prevalent silent brain infarction: a population-based study

BACKGROUND AND PURPOSE

The close relationship between stroke and chronic kidney disease (CKD) has been well-documented. However, few studies have focused on silent brain infarction (SBI) in CKD. We investigated the prevalence of SBI in different stages of CKD.

METHODS

We included 1312 participants aged 30 to 93 years who came from either a random sample of residents or from a group of physically examined subjects in the same community. Basic information, clinical evaluations, laboratory tests, and MRI images were assessed. Subjects were divided into groups 1, 2, 3a, and 3b, corresponding to the estimated glomerular filtration rate (eGFR) levels of ≥ 90.0, 60.0 to 89.9, 45.0 to 59.9, and 30.0 to 44.9 mL/min/1.73 m².

RESULTS

The crude prevalence was 4.7%: 2.6% (20 of 759 subjects) in group 1; 6.3% (32 of 506) in group 2; 12.9% (4 of 31) in group 3a; and 37.5% (6 of 16) in group 3b (P<0.001). Additionally, SBI also correlated with age, male sex, hypertension, diabetes, moderate carotid plaque, higher blood pressures, obesity, and levels of triglyceride, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein, and uric acid (all P<0.05). The effects for SBI risk in each eGFR group versus group 1 did not increase except for group 3b (OR, 9.34; P<0.001).

CONCLUSIONS

A close association exists between SBI and eGFR. We have found a significant increase in prevalence of SBI when eGFR is between 30.0 and 44.9 mL/min/1.73 m². Adults with late stage 3 CKD are at high risk for prevalent SBI.

Incident cognitive impairment is elevated in the stroke belt: the REGARDS study

OBJECTIVE

To determine whether incidence of impaired cognitive screening status is higher in the southern Stroke Belt region of the United States than in the remaining United States.

METHODS

A national cohort of adults age ≥45 years was recruited by the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study from 2003 to 2007. Participants' global cognitive status was assessed annually by telephone with the Six-Item Screener (SIS) and every 2 years with fluency and recall tasks. Participants who reported no stroke history and who were cognitively intact at enrollment (SIS >4 of 6) were included (N = 23,913, including 56% women; 38% African Americans and 62% European Americans; 56% Stroke Belt residents and 44% from the remaining contiguous United States and the District of Columbia). Regional differences in incident cognitive impairment (SIS score ≤4) were adjusted for age, sex, race, education, and time between first and last assessments.

RESULTS

A total of 1,937 participants (8.1%) declined to an SIS score ≤4 at their most recent assessment, over a mean of 4.1 (±1.6) years. Residents of the Stroke Belt had greater adjusted odds of incident cognitive impairment than non-Belt residents (odds ratio, 1.18; 95% confidence interval, 1.07-1.30). All demographic factors and time independently predicted impairment.

INTERPRETATION

Regional disparities in cognitive decline mirror regional disparities in stroke mortality, suggesting shared risk factors for these adverse outcomes. Efforts to promote cerebrovascular and cognitive health should be directed to the Stroke Belt.

Abnormal functional connectivity in patients with vascular cognitive impairment, no dementia: a resting-state functional magnetic resonance imaging study

The functional connectivity (FC) method was used to investigate the changes in the resting state of patients with vascular cognitive impairment, no dementia (VCIND). Resting-state functional magnetic resonance images (fMRIs) were acquired from 16 patients with subcortical ischemic vascular disease (SIVD) who fulfilled the criteria for VCIND, as well as 18 age- and sex-matched subjects with SIVD with no cognitive impairment (control group). Posterior cingulate cortex connectivity was gathered by investigating synchronic low-frequency fMRI signal fluctuations with a temporal correlation method. Compared with the control group, the patients showed FC decrease in the left middle temporal gyrus, the left anterior cingulate/left middle frontal gyrus, the right caudate, the right middle frontal gyrus, and the left medial frontal gyrus/paracentral lobule. There were also some regions that showed increased connectivity. These regions included the right inferior temporal gyrus, the left middle temporal gyrus, the left precentral gyrus, and the left superior parietal lobule. Our findings revealed the change in resting-state patterns of neuronal activity in patients with VCIND. This change may be caused by subcortical white matter lesions that destroyed direct and indirect fiber tract connectivity across the cerebral white matter and influenced the cortical FC and hypoperfusion resulted from small vascular disease. The results of the increased connectivity may be evoked by the compensatory recruitment and plasticity mechanism. Our findings suggest that the simplicity and noninvasiveness of this method makes it a potential tool to help thoroughly understand the pathogenesis of VCIND.

Mediterranean diet and magnetic resonance imaging-assessed cerebrovascular disease

OBJECTIVE

Cerebrovascular disease is 1 of the possible mechanisms of the previously reported relationship between Mediterranean-type diet (MeDi) and Alzheimer's disease (AD). We sought to investigate the association between MeDi and MRI infarcts.

METHODS

High-resolution structural MRI was collected on 707 elderly 65 years or older community residents of New York with available dietary assessments administered an average of 5.8 years (3.22 standard deviations [SDs]) before the MRI. Participants were divided into 3 groups of adherence to MeDi (low, middle, and high tertiles). We examined the association of increasing adherence to MeDi with presence of infarcts on MRI. Models were run without adjustment, adjusted for basic demographic and clinical factors, and adjusted for vascular risk factors.

RESULTS

A total of 222 participants had at least 1 infarct. In the unadjusted model, compared to the low adherence group, those in the moderate MeDi adherence group had a 22% reduced odds of having an infarct (odds ratio [OR], 0.78; 95% confidence interval [CI], 0.55-1.14), while participants in the highest MeDi adherence group had a 36% reduced odds (OR, 0.64; 95% CI, 0.42-0.97; p for trend = 0.04). In adjusted models, the association between MeDi adherence and MRI infarcts remained essentially unchanged. The association of high MeDi adherence with infarcts was comparable to that of hypertension (40% reduced probability), did not vary by infarct size or after excluding patients with dementia (n = 46) or clinical strokes (n = 86). There was no association between MeDi and white matter hyperintensities.

INTERPRETATION

Higher adherence to the MeDi is associated with reduced cerebrovascular disease burden.

Silent Brain Infarcts

Background and Purpose—

Silent brain infarcts (SBIs) have been recognized as common lesions in elderly subjects and their diagnosis relies on brain imaging. In this study, we aimed to evaluate the different MRI parameters and criteria used for their evaluation in the literature to better understand the variation across studies and related limitations.

Method—

Original MRI studies of SBI performed in human populations and reported in the English literature were reviewed. Analyses were restricted to population-based studies or studies in which at least 50 subjects with SBI were detected. The MRI parameters as well as the MRI criteria of SBI (size, signal characteristics, and criteria for differentiation of dilated Virchow-Robin spaces) were described and analyzed.

Result—

Magnetic field strength, slice thickness, and gap between slices greatly varied among the 45 articles included in this review. The MRI definition of SBI was inconsistent across studies. In half of them, SBI was defined as hypointense on T1 and hyperintense on T2-weighted images. Exclusion criteria for dilated Virchow-Robin spaces were used only in 7 studies.

Conclusions—

The variation in MRI characteristics and diagnostic criteria for SBI represent a major limitation for interpretation and comparison of data between studies. Efforts are needed to reach unified imaging criteria for SBI.

An embolic deflection device for aortic valve interventions

OBJECTIVES

We describe initial human experience with a novel cerebral embolic protection device.

BACKGROUND

Cerebral emboli are the major cause of procedural stroke during percutaneous aortic valve interventions.

METHODS

With right radial artery access, the embolic protection device is advanced into the aortic arch. Once deployed a porous membrane shields the brachiocephalic trunk and the left carotid artery deflecting emboli away from the cerebral circulation. Embolic material is not contained or removed by the device. The device was used in 4 patients (mean age 90 years) with severe aortic stenosis undergoing aortic balloon valvuloplasty (n = 1) or transcatheter aortic valve implantation (n = 3).

RESULTS

Correct placement of the embolic protection device was achieved without difficulty in all patients. Continuous brachiocephalic and aortic pressure monitoring documented equal pressures without evidence of obstruction to cerebral perfusion. Additional procedural time due to the use of the device was 13 min (interquartile range: 12 to 16 min). There were no procedural complications. Pre-discharge cerebral magnetic resonance imaging found no new defects in any of 3 patients undergoing transcatheter aortic valve implantation and a new 5-mm acute cortical infarct in 1 asymptomatic patient after balloon valvuloplasty alone. No patient developed new neurological symptoms or clinical findings of stroke.

CONCLUSIONS

Embolic protection during transcatheter aortic valve intervention seems feasible and might have the potential to reduce the risk of cerebral embolism and stroke.

Cerebral ischemia in young patients (under 45 years of age): clinical and neuroradiological follow-up

Ischemic stroke in young patients is a relatively rare event. Few studies have examined the long-term prognosis. The aim of this study was to evaluate the long-term outcome to identify clinical, laboratory and radiologic patterns as possible predictors for mortality, recurrence and functional recovery. We prospectively evaluated 94 patients (42 males and 52 females, aged 14-45 years, mean age 35.5 years, SD 8.4) admitted to our Neurological Department, for first acute ischemic stroke. A 48-month follow-up was performed. The patients were classified according to TOAST and Baltimore classification and Bamford criteria. The severity of the neurological deficit on admission was assessed using the NIHSS. The follow-up included a clinical visit, the modified Ranking scale (mRs) score, Barthel index (BI), and magnetic resonance imaging and intra-extracranial vessel Angio MRI. A good functional outcome (mRS 0-1) was found in 74 patients and unfavourable outcome (mRS 2-6) in 20 patients. 16 patients had a recurrent cerebral ischemic event: 5 patients had stroke and 11 patients had TIA. The average incidence annual rate of recurrence was 4.5% and a mortality rate was of 1.06%. Our study does not demonstrate any predictive factor related to clinical outcome. The relevant data of neuroradiological follow-up is the presence of clinically silent lesions in nine patients, considered as a recurrent stroke. To attribute a prognostic role to these lesions, clinical and neuroradiological follow-up needs to be continued.

Differing risk factors and outcomes in ischemic stroke subtypes: focus on lacunar stroke

Lacunar stroke has been a recognized stroke subtype for many years but its pathophysiology remains unknown, so prevention and treatment are suboptimal. Most lacunar strokes result from an intrinsic cerebral small vessel disease, probably part of a systemic disorder. Hypertension, diabetes and other vascular risk factors (but not atrial fibrillation and ipsilateral carotid stenosis) are equally common in lacunar as in large artery atherothromboembolic stroke, which, together with other factors, suggests that the patient’s response to vascular risk factors, not the vascular risk factors per se, determines whether they develop small vessel or large artery stroke. Inflammation and endothelial failure are probably involved in the pathogenesis of lacunar stroke, but their role needs to be clarified. The cerebral venules as well as arterioles are abnormal in this condition. The disorder may not be primarily ischemic; instead, arteriolar thrombosis may be a late-stage phenomenon secondary to chronic arteriolar wall damage resulting from leakage of plasma components across the BBB. Accurate diagnosis of lacunar stroke, avoiding risk factor-based classifications, is required to underpin future research.

Association of serum soluble receptor for advanced glycation end-products with subclinical cerebrovascular disease: the Northern Manhattan Study (NOMAS)

OBJECTIVE

Serum levels of the soluble receptor for advanced glycation end-products (sRAGE) have been associated with risk of cardiovascular disease. We hypothesized that sRAGE levels are associated with subclinical cerebrovascular disease in an ethnically diverse population.

METHODS

Clinically stroke-free participants in the multi-ethnic Northern Manhattan Study (NOMAS) underwent brain MRI to quantify subclinical brain infarcts (SBI) and white matter hyperintensity volume (WMHV) (n = 1102). Serum levels of sRAGE were measured by ELISA. Logistic and multiple linear regression were employed to estimate associations of sRAGE with SBI and WMHV, after adjusting for demographics and vascular risk factors.

RESULTS

Median sRAGE levels were significantly lower in Hispanics (891.9 pg/ml; n = 708) and non-Hispanic blacks (757.4 pg/ml; n = 197) than in non-Hispanic whites (1120.5 pg/ml; n = 170), and these differences remained after adjusting for other risk factors. Interactions were observed by race-ethnicity between sRAGE levels and MRI measurements, including for SBI in Hispanics (p = 0.04) and WMHV among blacks (p = 0.03). In Hispanics, increasing sRAGE levels were associated with a lower odds of SBI, with those in the upper sRAGE quartile displaying a 50% lower odds of SBI after adjusting for sociodemographic and vascular risk factors (p = 0.05). Among blacks, those in the upper quartile of sRAGE had a similarly reduced increased risk of SBI (p = 0.06) and greater WMHV (p = 0.04).

CONCLUSION

Compared to whites, Hispanics and blacks have significantly lower sRAGE levels, and these levels were associated with more subclinical brain disease. Taken together, these findings suggest sRAGE levels may be significantly influence by ethnicity. Further studies of sRAGE and stroke risk, particularly in minorities, are warranted.

Reduced severity of strokes in patients with silent brain infarctions

BACKGROUND

Silent brain infarctions (SBIs), leukoaraiosis (LA), and microbleeds (MBs) are ischaemic silent radiologic abnormalities that act as predictors of subsequent strokes. This study investigated the independent effect of silent radiologic abnormalities on initial stroke severity and short-term outcome.

METHODS

A consecutive series of patients who had their first ischaemic stroke within 72 h of symptom onset were included. Demographic and clinical characteristics were collected on admission, and magnetic resonance imaging was performed to evaluate the ischaemic lesion, SBI, LA, and MB. Factors potentially associated with lower initial stroke severity (admission NIH Stroke Scale 0-5) and good short-term outcome (discharge NIH Stroke Scale 0-5, modified Rankin Scale 0-1) were validated by multivariate analysis.

RESULTS

Silent brain infarctions were noted in 82 (45%) of the 182 patients. Although there were no statistically significant differences in stroke subtypes and lesion location, univariate analysis revealed that patients with SBI had reduced stroke severity (P = 0.005) and infarction volume (P = 0.001). After adjusting for covariates, the presence of SBI was independently associated with lower stroke severity and good short-term outcome when the NIH Stroke Scale was used as dependent variable (OR 3.368, 95% CI 1.361-8.332, P = 0.009; OR 3.459, 95% CI 1.227-9.755, P = 0.019, respectively). However, the presence of SBI lost significance when the discharge-modified Rankin Scale was used as dependent variable (P = 0.058).

CONCLUSION

Amongst silent radiologic abnormalities, SBI was the only predictor of reduced stroke severity and infarct volume. Silent brain infarction deserves more attention in evaluating stroke severity.

Advanced coronary artery calcification and cerebral small vessel diseases in the healthy elderly

BACKGROUND

Coronary artery calcification (CAC) scores are widely accepted to predict risk of coronary heart diseases and are associated with atherosclerosis in other vasculatures. Cerebral small vessel diseases (SVDs), including white matter lesions (WML), silent lacunar infarction (SLI) and cerebral microbleeds (CMB), are considered to develop in conjunction with pro-atherogenic conditions, measured by CAC scores.

METHODS AND RESULTS

Of 672 individuals aged ≥65 years that underwent health screening, 312 subjects with brain magnetic resonance imagings (MRIs) were enrolled in this study. The distribution of baseline characteristics among individuals with or without MRIs was not different. Clinical and laboratory information was collected and CAC scores were measured using multi-detector computed tomography. Cerebral SVD were independently assessed by 2 raters who were unaware of the CAC scores. The prevalence of CAC (CAC>0) was 71.7% in men and 50.0% in women. The associations between moderate-to-extensive CAC (CAC score ≥100) and WML (adjusted odds ratio and 95% confidence interval, 4.99 and 1.33-18.73), SLI (5.04 and 1.86-13.63) and CMB (6.07 and 1.54-23.94) remained significant after adjusting for relevant confounders.

CONCLUSIONS

This study documents significant associations between CAC and cerebral SVDs. The findings suggest that SVDs in the brain and CAC in the heart may develop under similar systemic pathogenic processes.

Vascular basis for brain degeneration: faltering controls and risk factors for dementia

The integrity of the vascular system is essential for the efficient functioning of the brain. Aging-related structural and functional disturbances in the macro- or microcirculation of the brain make it vulnerable to cognitive dysfunction, leading to brain degeneration and dementing illness. Several faltering controls, including impairment in autoregulation, neurovascular coupling, blood-brain barrier leakage, decreased cerebrospinal fluid, and reduced vascular tone, appear to be responsible for varying degrees of neurodegeneration in old age. There is ample evidence to indicate vascular risk factors are also linked to neurodegenerative processes preceding cognitive decline and dementia. The strongest risk factor for brain degeneration, whether it results from vascular or neurodegenerative mechanisms or both, is age. However, several modifiable risks such as cardiovascular disease, hypertension, dyslipidemia, diabetes, and obesity enhance the rate of cognitive decline and increase the risk of Alzheimer's disease in particular. The ultimate accumulation of brain pathological lesions may be modified by genetic influences, such as the apolipoprotein E ε4 allele and the environment. Lifestyle measures that maintain or improve cardiovascular health, including consumption of healthy diets, moderate use of alcohol, and implementation of regular physical exercise are important factors for brain protection.

Lysophosphatidic acid level and the incidence of silent brain infarction in patients with nonvalvular atrial fibrillation

Lysophosphatidic acid (LPA), which is proposed to play an important role in normal physiological situations such as wound healing, vascular tone, vascular integrity and reproduction, may be involved in the etiology of some diseases such as atherosclerosis, cancer, obesity or myocardial infarction. Abnormal findings, including silent brain infarction (SBI), are frequently observed by magnetic resonance imaging (MRI) in patients with nonvalvular atrial fibrillation (NVAF). However, whether there is a relationship between LPA level and the prevalence of SBI has not been extensively studied. In the present study, the association between them was investigated. 235 patients with NVAF, 116 cases of SBI without NVAF and 120 cases of healthy volunteers (control group), who did not receive any antithrombotic therapy, were enrolled in this study. Plasma LPA levels in the NVAF with SBI group were significantly higher than that in the control group (p < 0.01), NVAF without SBI group (p < 0.01) and SBI without NVAF group (p < 0.01). The LPA levels are lower in the control group than in the NVAF without SBI and SBI without NVAF groups (p < 0.01), however, the latter two groups did not significantly differ from each other for LPA levels (p > 0.05) There were significant differences in the positive rate of platelet activation between each of the groups (p < 0.01). The positive rate of platelet activation was significantly higher in the NVAF with SBI group. We suggest that LPA might be a novel marker for estimation of the status of platelet activation and the risk factor for SBI onset in NVAF patients. We expected that plasma LPA levels could predict the occurrence of SBI in NVAF patients.

Depressive symptoms are associated with subclinical cerebrovascular disease among healthy older women, not men

BACKGROUND

Associations among diagnosed unipolar depression, depressive symptoms, and cerebrovascular disease are well known. However, minimal research has investigated whether sex may modify such associations, despite known sex differences in depression and depressive symptoms. This study examined whether depressive symptoms were disproportionately related to subclinical cerebrovascular disease (SCD) in women versus men.

METHODS

One hundred one older adults (58% men; mean age = 67 years), free of major comorbidities, completed the Beck Depression Inventory and underwent magnetic resonance imaging (MRI). MRI scans were neuroradiologist rated for markers of SCD (periventricular and deep white matter hyperintensities, and number of silent infarcts) and brain atrophy (ventricular enlargement and sulcal widening). Two rank-sum outcome variables (SCD and brain atrophy) were then created.

RESULTS

On average, depressive symptoms were relatively low in magnitude (mean = 3.8, standard deviation = 3.6, range = 0-17). Multiple regression analyses, adjusted for age, sex, education, systolic blood pressure, fasting glucose, maximal oxygen consumption, body mass index, average weekly alcohol consumption, and Mini-Mental State Examination performance revealed sex to be a significant effect modifier of depressive symptoms in the prediction of SCD. Sex-stratified regression analyses indicated depressive symptoms, and SCD was strongly related among women but not men. Depressive symptoms were not related to brain atrophy, regardless of inclusion of sex as an effect modifier.

CONCLUSIONS

Depressive symptoms, even in a subclinical range, are significantly associated with an MRI-derived index of SCD among women, but not men, in the present sample of relatively healthy older adults.

Lesion Explorer: a comprehensive segmentation and parcellation package to obtain regional volumetrics for subcortical hyperintensities and intracranial tissue

Subcortical hyperintensities (SH) are a commonly observed phenomenon on MRI of the aging brain (Kertesz et al., 1988). Conflicting behavioral, cognitive and pathological associations reported in the literature underline the need to develop an intracranial volumetric analysis technique to elucidate pathophysiological origins of SH in Alzheimer's disease (AD), vascular cognitive impairment (VCI) and normal aging (De Leeuw et al., 2001; Mayer and Kier, 1991; Pantoni and Garcia, 1997; Sachdev et al., 2008). The challenge is to develop processing tools that effectively and reliably quantify subcortical small vessel disease in the context of brain tissue compartments. Segmentation and brain region parcellation should account for SH subtypes which are often classified as: periventricular (pvSH) and deep white (dwSH), incidental white matter disease or lacunar infarcts and Virchow-Robin spaces. Lesion Explorer (LE) was developed as the final component of a comprehensive volumetric segmentation and parcellation image processing stream built upon previously published methods (Dade et al., 2004; Kovacevic et al., 2002). Inter-rater and inter-method reliability was accomplished both globally and regionally. Volumetric analysis showed high inter-rater reliability both globally (ICC=.99) and regionally (ICC=.98). Pixel-wise spatial congruence was also high (SI=.97). Whole brain pvSH volumes yielded high inter-rater reliability (ICC=.99). Volumetric analysis against an alternative kNN segmentation revealed high inter-method reliability (ICC=.97). Comparison with visual rating scales showed high significant correlations (ARWMC: r=.86; CHIPS: r=.87). The pipeline yields a comprehensive and reliable individualized volumetric profile for subcortical vasculopathy that includes regionalized (26 brain regions) measures for: GM, WM, sCSF, vCSF, lacunar and non-lacunar pvSH and dwSH.

Blood-brain barrier and cerebral small vessel disease

Increasing evidence from neuro and retinal imaging, neuropathology, epidemiology and experimental models suggests that the primary underlying initiating cause of cerebral small vessel disease is the derangement of the blood-brain barrier. This may start some years before the first symptoms, leads to the small vessel structural changes (vessel wall thickening, disorganisation and eventual breakdown) and perivascular changes (oedema, enlarged perivascular spaces, tissue damage interpreted as "infarcts") and is fundamentally different to traditional "ischaemic" mechanisms, although small vessel occlusion due to thrombus formation on damaged vessel walls may be a late secondary phenomenon. Space limits a detailed discussion of the epidemiology and experimental evidence, so this brief review will focus on neuroimaging evidence and summarise the appearances, risk factors and associations of different components of cerebral small vessel disease as identified on imaging, discuss potential causes and, in particular, the evidence that disordered blood-brain barrier precipitates or worsens progression of cerebral small vessel disease. This mechanism may also play a role in other common disorders of ageing such as Alzheimer's disease.

Risk of "silent stroke" in patients older than 60 years: risk assessment and clinical perspectives

With the increasing size of the elderly population and evolving imaging technology, silent brain infarction (SBI) has garnered attention from both the public and the physicians. Over 20% of the elderly exhibit SBI, and the prevalence of SBI increases steadily with age, ie, 30%–40% in those older than 70 years. Well-known cardiovascular risk factors such as hypertension has been identified as a risk factor of SBI (odds ratio [OR] = 3.47) Besides this, blood pressure (BP) reactivity to mental stress, morning BP surges, and orthostatic BP changes have been demonstrated to contribute to the presence of SBI. Further, a metabolic syndrome not only as a whole syndrome (OR =2.18) but also as individual components could have an influence on SBI. Increased C-reactive protein and interleukin-6, coronary artery disease, body mass index, and alcohol consumption have also been associated with SBI. The ORs and possible mechanisms have been discussed in this article. Overt stroke, dementia, depression, and aspiration pneumonia were all associated with SBI. (overt stroke: hazard ratio [HR] =1.9, 95% confidence interval [CI]: 1.2–2.8; dementia: HR =2.26, 95% CI: 1.09–4.70). We also looked into their close relationship with SBI in this review.

Lenticulostriate Arteries in Chronic Stroke Patients Visualised by 7 T Magnetic Resonance Angiography

Background

Noninvasive magnetic resonance angiography using ultra-high-field magnetic resonance imaging has recently provided us with the potential to image cerebral microvascular structures such as the lenticulostriate arteries. However, most studies using ultra-high-field magnetic resonance angiography have been limited to the visualisation of microvessels in healthy subjects, and the direct comparison of patients with microvascular disease has not been reported.

Aim

The aim of this study was to investigate the lenticulostriate arteries of patients with lacunar strokes of the basal ganglia and surrounding areas using 7 T magnetic resonance angiography.

Methods

Ten stroke patients who had infarctions in the basal ganglia and adjacent areas detected using T2*-weighted images obtained from a conventional 1.5 T magnetic resonance imaging and 10 age-matched healthy subjects were recruited for this study. The large main vessels in the patient group were inspected to identify abnormalities such as stenosis. The characteristics of the lenticulostriate arteries visualised by 7 T magnetic resonance angiography, such as the number of branches and stems, curvature and tortuosity were analysed and compared between the patient and the control groups.

Results

All patients had infarctions in the basal ganglia and adjacent regions, which were clearly determined by T2*-weighted images. However, there was no evidence of large-vessel abnormalities in the patient group. Analysis of 7 T magnetic resonance angiography data revealed that the overall number of lenticulostriate arteries branches in the patient group was significantly less than the control group ( P = 0.003). However, no statistical difference in the number of stems, curvature and tortuosity between the two groups was found ( P = 0.396, 0.258 and 0.888, respectively).

Conclusions

This study demonstrates that noninvasive magnetic resonance angiography using 7 T magnetic resonance imaging can visualise abnormalities in the cerebral microvasculature of stroke patients, and that the number of lenticulostriate arteries supplying the region of the basal ganglia is less in these patients compared with age-matched controls.