MRI Detection of New Microbleeds in Patients With Ischemic Stroke

Cerebral microbleeds and asundexian in non-cardioembolic ischemic stroke: Secondary analyses of the PACIFIC-STROKE randomized trial

BACKGROUND AND AIMS

Cerebral microbleeds are magnetic imaging resonance (MRI) markers of hemorrhage-prone cerebral small vessel disease that predict future risk of ischemic stroke and intracranial hemorrhage (ICrH). There exist concerns about the net benefit of antithrombotic therapy in patients with microbleeds. We aimed to investigate the effects of an oral factor-XIa inhibitor (asundexian), that is hypothesized to inhibit thrombosis without compromising hemostasis, on the development of new microbleeds over time and interactions between microbleeds and asundexian treatment on clinical outcomes. We additionally assessed associations between baseline microbleeds and the risks of clinical and neuroimaging outcomes in patients with non-cardioembolic ischemic stroke.

METHODS

This is a secondary analysis of the PACIFIC-STROKE, international, multi-center Phase 2b double-blind, randomized clinical trial. PACIFIC-STROKE enrolled patients aged ⩾ 45 years with mild-to-moderate non-cardioembolic ischemic stroke who presented within 48 h of symptom onset for whom antiplatelet therapy was intended. Microbleeds were centrally adjudicated, and participants with an interpretable T2*-weighted sequence at their baseline MRI were included in this analysis. Patients were randomized to asundexian (10/20/50 mg daily) versus placebo plus standard antiplatelet treatment. Regression models were used to estimate the effects of (1) all pooled asundexian doses and (2) asundexian 50 mg daily on new microbleed formation on 26-week MRIs. Cox proportional hazards or regression models were additionally used to estimate interactions between treatment assignment and microbleeds for ischemic stroke/transient ischemic attack (TIA) (primary outcome), and ICrH, all-cause mortality, hemorrhagic transformation (HT), and new microbleeds (secondary outcomes).

RESULTS

Of 1746 participants (mean age, 67.0 ± 10.0; 34% female) with baseline MRIs, 604 (35%) had microbleeds. During a median follow-up of 10.6 months, 7.0% (n = 122) had ischemic stroke/TIA, 0.5% (n = 8) ICrH, and 2.1% (n = 37) died. New microbleeds developed in 10.3% (n = 155) of participants with adequate follow-up MRIs and HT in 31.4% (n = 345). In the total sample of patients with adequate baseline and 26-week follow-up MRIs (n = 1507), new microbleeds occurred in 10.2% of patients assigned to any asundexian dose and 10.5% of patients assigned to placebo (OR, 0.96; 95% CI, 0.66-1.41). There were no interactions between microbleeds and treatment assignment for any of the outcomes (p for interaction > 0.05). The rates of new microbleeds, HT, and ICrH were numerically less in patients with microbleeds assigned to asundexian relative to placebo. The presence of microbleeds was associated with a higher risk of HT (aOR, 1.6; 95% CI, 1.2-2.1) and new microbleeds (aOR, 4.4; 95% CI, 3.0-6.3).

CONCLUSION

Factor XIa inhibition with asundexian appears safe in patients with non-cardioembolic ischemic stroke and hemorrhage-prone cerebral small vessel disease marked by microbleeds on MRI. These preliminary findings will be confirmed in the ongoing OCEANIC-STROKE randomized trial.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04304508.

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

A multicenter, prospective, randomized controlled trial of intracranial hemorrhage risk of intensive statin therapy in patients with acute ischemic stroke combined with cerebral microbleeds (CHRISTMAS): Study protocol

Background

Low serum levels of major lipid markers have been proved to be significantly associated with increased risks of hemorrhagic stroke (HS) and cerebral microbleeds (CMBs). However, there is no lipid modification guideline telling us how to maintain a balance between the prevention of ischemic stroke recurrence and the prevention of hemorrhagic events, especially in patients with acute ischemic stroke (AIS) and CMBs.

Aim

The Intracranial Hemorrhage Risk of Intensive Statin Therapy in Patients with Acute Ischemic Stroke combined with Cerebral Microbleeds (CHRISTMAS) trial evaluates the risk of intracranial hemorrhage (i.e., HS and CMBs) of high-dose statin therapy in patients with AIS combined with CMBs.

Methods and design

This is an investigator-initiated, multicenter, prospective, randomized controlled clinical trial design. Up to 344 eligible patients will be consecutively randomized to receive high-dose or low-dose atorvastatin in 1:1 ratio in 5 stroke centers in China.

Outcomes

CHRISTMAS trial has co-primary outcomes, namely, hemorrhage risk: the incidence of HS and the changes in degree of CMBs until the end of 36-month follow-up.

Discussion

The primary hypothesis of this study is that an excessive reduction in serum lipid levels by an intensive statin therapy in AIS patients with CMBs can increase the risk of intracranial hemorrhage. This study will shed light on new clinical decisions regarding the long-term serum lipid management in these patients with dilemma in clinical practice.

Clinical trial registration

Clinicaltrials.gov, identifier: NCT05589454.

Association between frailty index based on routine laboratory tests and risk of cerebral small vessel disease in elderly patients: a hospital-based observational study

BACKGROUND

The association between frailty and cerebral small vessel disease (CSVD) remains controversial due to the use of different methods to assess frailty, including physical frailty phenotype and frailty scores containing measures of cognition. A frailty index based on laboratory tests (FI-Lab), which assesses frailty by the combination of routine laboratory measures and several vital signs, is independent of cognition and function status. We aimed to evaluate the association of FI-Lab with CSVD.

METHODS

An observational study was carried out in a hospitalized cohort of older patients with minor ischemic stroke or TIA. The FI-Lab was constructed by 20 routine laboratory tests, plus systolic blood pressure, diastolic blood pressure, and pulse pressure. Manifestations of CSVD including white matter hyperintensity (WMH), silent lacunar infarcts, microbleed, enlarged perivascular spaces (EPVS), as well as deep brain atrophy, were measured on magnetic resonance imaging (MRI). An ordinal score system constructed by WMH, EPVS, silent lacunar infarcts, and microbleed was used to reflect the total burden of CSVD. The associations between FI-lab and CSVD were examined by logistic regression analysis and ordinal regression.

RESULTS

A total of 398 patients were recruited from January 2016 to December 2018. The mean FI-Lab value was 0.26 ± 0.11. The prevalence of extensive periventricular WMH, extensive deep WMH, extensive basal ganglia EPVS, extensive centrum semiovale EPVS, silent lacunar infarcts, and deep microbleed was 26.1, 66.6, 68.6, 80.7, 32.9, and 6.5%, respectively. A higher FI-Lab value was associated with increased risks of extensive deep WMH (OR = 1.622; 95% CI, 1.253 ~ 2.100), extensive basal ganglia EPVS (OR = 1.535; 95% CI, 1.187 ~ 1.985), extensive centrum semiovale EPVS (OR = 1.584; 95% CI, 1.167 ~ 2.151), silent lacunar infarcts (OR = 1.273; 95% CI, 1.007 ~ 1.608), and higher total burden of CSVD. These associations remained after the adjustment of potential confounding factors.

CONCLUSION

This study demonstrated that a higher FI-Lab score might be associated with the presence of WMH, EPVS, silent lacunar infarcts, as well as severe total CSVD burden in older patients with minor stroke or TIA. The FI-Lab provides a basis for the prediction of CSVD.

New cerebral microbleeds in AF patients on non-vitamin K oral anticoagulants or warfarin: One-year follow-up

Anticoagulant treatment increases the risk of intracerebral hemorrhage (ICH), but whether the treatment, more specifically non-vitamin K oral anticoagulants (NOACs), increases the risk of cerebral microbleeds (CMBs) remains uncertain. We performed this study to investigate the development of new CMBs due to NOACs or warfarin treatment in patients with atrial fibrillation (AF).We prospectively recruited AF patients before anticoagulation from June 2016 to June 2018. We performed susceptibility-weighted imaging (SWI) examinations on all enrolled AF patients and re-examined SWI 1 year later. We compared demographic features and new CMBs between the NOACs group and the warfarin group. Univariate analysis of clinical factors was performed according to the development of new CMBs; and age, a HAS-B(L)ED score, warfarin use, and the presence of baseline CMBs were then selected for inclusion in the multivariate logistic regression model.A total of 72 AF patients were recruited, 29 of whom were assigned to the NOACs group and 43 to the warfarin group. Finally, 1 patient in the NOACs group (3.4%) and 9 patients (20.9%) in the warfarin group developed new CMBs after 1 year follow-up (P = .08). Univariate analysis showed that age, a HAS-B(L)ED score ≥4, the presence of baseline CMBs were associated with the development of new CMBs (P < .05). And multivariate regression analysis showed baseline CMBs (P = .03, odds ratio = 6.37, 95% confidence interval 1.15-35.36) was independently related to the increase in new CMBs.AF patients treated with NOACs may have a decreased trend in the development of new CMBs compared with those treated with warfarin. Baseline CMBs increased the frequency of new CMBs during anticoagulant treatment. The development of new CMBs in AF patients with anticoagulation requires further longitudinal studies with longer follow-up in larger samples.

Dysfunction of the Blood-brain Barrier in Cerebral Microbleeds: from Bedside to Bench

Cerebral microbleeds (CMBs) are a disorder of cerebral microvessels that are characterized as small (<10 mm), hypointense, round or ovoid lesions seen on T2*-weighted gradient echo MRI. There is a high prevalence of CMBs in community-dwelling healthy older people. An increasing number of studies have demonstrated the significance of CMBs in stroke, dementia, Parkinson's disease, gait disturbances and late-life depression. Blood-brain barrier (BBB) dysfunction is considered to be the event that initializes CMBs development. However, the pathogenesis of CMBs has not yet been clearly elucidated. In this review, we introduce the pathogenesis of CMBs, hypertensive vasculopathy and cerebral amyloid angiopathy, and review recent research that has advanced our understanding of the mechanisms underlying BBB dysfunction and CMBs presence. CMBs-associated risk factors can exacerbate BBB breakdown through the vulnerability of BBB anatomical and functional changes. Finally, we discuss potential pharmacological approaches to target the BBB as therapy for CMBs.

Cerebral Microbleeds Load and Long-Term Outcomes in Minor Ischemic Stroke

BACKGROUND AND PURPOSE

The association between the cerebral microbleed (CMB) count and outcomes in ischemic stroke has not been fully clarified. The aim of this study was to investigate the relationship between the CMBs count and functional outcomes in patients with a minor ischemic stroke treated with antiplatelet therapy METHODS: Non-cardiogenic minor ischemic stroke (NIHSS score < 4 on admission) patients who were treated with antiplatelet therapy were enrolled. The patients were divided into four groups based on the number of CMBs (absent, 1, 2-4, and > 4), and their clinical outcomes were compared. A poor outcome was defined as a modified Rankin scale (mRS) score of 3-6 90 days after symptom onset. Logistic regression analysis was performed to evaluate whether the CMBs count contributes to poor outcomes with well-known risk factors such as age, NIHSS score on admission, ischemic stroke recurrence, large artery atherosclerosis stroke subtype, and DWMHs.

RESULTS

A total of 240 patients were enrolled, and their pre mRS scores were matched based on CMB presence. A higher burden of CMBs was linearly correlated with the incidence of poor outcomes (4% in the absent group, 8% in the 1 CMB group, 13% in the 2-4 CMB group, and 20% in the > 4 CMB group, P = 0.002). Multivariate logistic regression analysis showed that CMBs count was one of the independent factor associated with poor outcomes (odds ratio 1.07, 95% confidence interval 1.02-1.12, P = 0.003).

CONCLUSION

The CMBs count contributes independently to poor outcomes in minor ischemic stroke patients treated with antiplatelet therapy.

Factors associated with the presence of cerebral microbleeds and its influence on outcomes of stroke not treated with alteplase

OBJECTIVES

Cerebral microbleeds (CMB) are associated with increased risk of hemorrhagic transformation (HT) of ischemic stroke with alteplase. Whether the presence of CMB influences the risk of HT and discharge outcomes of stroke patients not receiving alteplase is unclear. We evaluated the factors associated with the presence of CMB, and if the rates of HT and discharge outcomes were modified by the presence of CMB among stroke patients not treated with alteplase.

METHODS

Ischemic stroke patients who had MRI and did not receive alteplase were included in the study. CMB, HT and white matter hyperintensity (WMH) were evaluated using Microbleed Anatomical Rating Scale, Heidelberg bleeding classification, and Fazekas scales, respectively. Multivariate regression analysis was performed to evaluate factors associated with the presence of CMB.

RESULTS

Among 196 patients in the study, 58 (30%) patients had CMB. Nine patients had ≥ 10 CMBs. Median National Institutes of Health stroke scale score was 4. In multivariate analysis, age (OR=1.07;95%CI=1.01-1.12), history of stroke (OR=3.10;95%CI=1.08-8.92), congestive heart failure (OR=7.26;95%CI=1.58-33.42), admission diastolic blood pressure (OR=1.03;95%CI=1.003-1.06) and severe WMH defined as Fazekas score 4-6 (OR=4.69;95%CI=1.80-12.23) were significantly associated with the presence of CMB. There was no difference in HT (10% vs 12%, p = 0.80) or discharge outcomes (modified Rankin Scale 0-2: 53% vs 57%, p = 0.62) of patients with CMB compared to those without CMB.

CONCLUSION

CMB are associated with severe WMH and higher diastolic blood pressure. CMB are not associated with the HT occurrence or discharge outcome of mild ischemic stroke in the absence of alteplase.

Two-Minute Quantitative Susceptibility Mapping From Three-Dimensional Echo-Planar Imaging: Accuracy, Reliability, and Detection Performance in Patients With Cerebral Microbleeds

OBJECTIVES

The aim of this study was to assess the accuracy, reliability, and cerebral microbleed (CMB) detection performance of 2-minute quantitative susceptibility mapping (QSM) from 3-dimensional echo-planar imaging (3D-EPI).

MATERIALS AND METHODS

Gadolinium phantom study was conducted using 3D-EPI, single-echo time (TE), and multi-TE gradient-recalled echo (GRE) sequences on two 3-T magnetic resonance (MR) scanners to assess the accuracy between measured and theoretical susceptibility values. The institutional review board approved this prospective study, and 40 healthy volunteers were enrolled with written consent between April 2018 and October 2019. Each underwent 3D-EPI, single-TE, and multi-TE GRE sequences consecutively on one 3-T MR scanner, and QSMs were calculated to assess the reliability of 3D-EPI QSM. Intraclass correlation coefficient (ICC), linear regression, and Bland-Altman plots were calculated. Patients with CMB who underwent both 3D-EPI and GRE QSM scans were retrospectively enrolled. Two radiologists evaluated images independently, and Cohen κ coefficients were calculated to compare CMB detection performance.

RESULTS

Phantom study showed excellent validity of 3D-EPI QSM on both MR scanners: Skyra, R2 = 0.996, P < 0.001, ICC = 0.997, mean difference, -2 ppb (95% confidence interval [CI], -45 to 40 ppb); Prisma, R2 = 0.992, P < 0.001, ICC = 0.988, mean difference, 15 ppb (95% CI, -67 to 97 ppb). A human study of 40 healthy volunteers (59 ± 13 years, 25 women) showed excellent reliability with 3D-EPI QSM for both single-TE and multi-TE GRE (R2 = 0.981, P < 0.001, ICC = 0.988; R2 = 0.983, P < 0.001, ICC = 0.990, respectively), supported by a Bland-Altman mean difference of 4 ppb (95% CI, -15 to 23 ppb) for single-TE GRE and 3 ppb (95% CI, -15 to 20 ppb) for multi-TE GRE. The CMB detection performance evaluation from 38 patients (51 ± 20 years, 20 women) showed almost perfect agreement between 3D-EPI and GRE QSM for both raters (κ = 0.923 and 0.942, P < 0.001).

CONCLUSIONS

Faster QSM from 3D-EPI demonstrated excellent accuracy, reliability, and CMB detection performance.

Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a cluster of various vascular disorders with different pathological backgrounds. The advanced vasculature net of cerebral vessels, including small arteries, capillaries, arterioles and venules, is usually affected. Processes of oxidation underlie the pathology of CSVD, promoting the degenerative status of the epithelial layer. There are several classifications of cerebral small vessel diseases; some of them include diseases such as Binswanger’s disease, leukoaraiosis, cerebral microbleeds (CMBs) and lacunar strokes. This paper presents the characteristics of CSVD and the impact of the current knowledge of this topic on the diagnosis and treatment of patients.

Longitudinal Magnetic Resonance Imaging of Cerebral Microbleeds in Multiple Sclerosis Patients

We hypothesized that cerebral microbleeds (CMBs) in multiple sclerosis (MS) patients will be detected with higher prevalence compared to healthy controls (HC) and that quantitative susceptibility mapping (QSM) will help remove false positives seen in susceptibility weighted imaging (SWI). A cohort of 100 relapsing remitting MS subjects scanned at 3T were used to validate a set of CMB detection guidelines specifically using QSM. A second longitudinal cohort of 112 MS and 25 HCs, also acquired at 3T, was reviewed across two time points. Both cohorts were imaged with SWI and fluid attenuated inversion recovery. Fourteen subjects in the first cohort (14%, 95% CI 8-21%) and twenty-one subjects in the second cohort (18.7%, 95% CI 11-27%) had at least one CMB. The combined information from SWI and QSM allowed us to discern stable CMBs and new CMBs from potential mimics and evaluate changes over time. The longitudinal results demonstrated that longer disease duration increased the chance to develop new CMBs. Higher age was also associated with increased CMB prevalence for MS and HC. We observed that MS subjects developed new CMBs between time points, indicating the need for longitudinal quantitative imaging of CMBs.

Intracerebral haemorrhage, microbleeds and antithrombotic drugs

Antithrombotic therapy is a cornerstone for secondary prevention of ischaemic events, cerebral and extra-cerebral. A number of clinical questions remain unanswered concerning the impact of antithrombotic drugs on the risk of first-ever and recurrent macro or micro cerebral haemorrhages, raising the clinical dilemma on the risk/benefit balance of giving antiplatelets and anticoagulants in patients with potential high risk of brain bleeds. High field magnetic resonance imaging (MRI) blood-weighted sequences, including susceptibility weighted imaging (SWI), have expanded the spectrum of these clinical questions, because of their increasing sensitivity in detecting radiological markers of small vessel disease. This review will summarise the literature, focusing on four main clinical questions: how do cerebral microbleeds impact the risk of cerebrovascular events in healthy patients, in patients with previous ischaemic stroke or transient ischaemic attack, and in patients with intracerebral haemorrhage? Is the risk/benefit balance of oral anticoagulants shifted by the presence of microbleeds in patients with atrial fibrillation after recent ischaemic stroke or transient ischaemic attack? Should we restart antiplatelet drugs after symptomatic intracerebral haemorrhage or not? Are oral anticoagulants allowed in patients with a history of atrial fibrillation and previous intracerebral haemorrhage?

Contrast leakage distant from the hematoma in patients with spontaneous ICH: A 7 T MRI study

Disruption of the blood-brain barrier (BBB) might play a role in the pathophysiology of cerebral small vessel disease-related ICH. The aim of this study was to assess presence and extent of contrast agent leakage distant from the hematoma as a marker of BBB disruption in patients with spontaneous ICH. We prospectively performed 7 tesla MRI in adult patients with spontaneous ICH and assessed contrast leakage distant from the hematoma on 3D FLAIR images. Thirty-one patients were included (mean age 60 years, 29% women). Median time between ICH and MRI was 20 days (IQR 9-67 days). Seventeen patients (54%; seven lobar, nine deep, one infratentorial ICH) had contrast leakage, located cortical in 16 and cortical and deep in one patient. Patients with contrast leakage more often had lobar cerebral microbleeds (CMBs; 77%) than those without (36%; RR 2.5, 95% CI 1.1-5.7) and a higher number of lobar CMBs (patients with contrast leakage: median 2, IQR 1-8 versus those without: median 0, IQR 0-2; p = 0.02). This study shows that contrast leakage distant from the hematoma is common in days to weeks after spontaneous ICH. It is located predominantly cortical and related to lobar CMBs and therefore possibly to cerebral amyloid angiopathy.

Use of anticoagulant therapy and cerebral microbleeds: a systematic review and meta-analysis

BACKGROUND

Anticoagulant therapy increases the risk that cerebral microbleeds (CMBs) progress to intracerebral hemorrhage, but whether the therapy increases risk of CMB occurrence is unclear. We performed a systematic review and meta-analysis to investigate the potential association between anticoagulant use and CMB occurrence in stroke and stroke-free individuals.

METHODS

We searched observational studies in PubMed, Ovid EMBASE, and Cochrane Library from their inception until September 2019. We calculated the pooled odds ratio (OR) and 95% confidence interval (CI) for the prevalence and incidence of CMBs in anticoagulant users relative to non-anticoagulant users.

RESULTS

Forty-seven studies with 25,245 participants were included. The pooled analysis showed that anticoagulant use was associated with CMB prevalence (OR 1.54, 95% CI 1.26-1.88). The association was observed in subgroups stratified by type of participants: stroke-free, OR 1.86, 95% CI 1.25-2.77; ischemic stroke/transient ischemic attack, OR 1.33, 95% CI 1.06-1.67; and intracerebral hemorrhage, OR 2.26, 95% CI 1.06-4.83. Anticoagulant use was associated with increased prevalence of strictly lobar CMBs (OR 1.68, 95% CI 1.22-2.32) but not deep/infratentorial CMBs. Warfarin was associated with increased CMB prevalence (OR 1.64, 95% CI 1.23-2.18), but novel oral anticoagulants were not. Anticoagulant users showed higher incidence of CMBs during long-term follow-up (OR 1.72, 95% CI 1.22-2.44).

CONCLUSION

Anticoagulant use is associated with higher prevalence and incidence of CMBs. This association appears to depend on location of CMBs and type of anticoagulants. More longitudinal investigations with adjustment for confounders are required to establish the causality.

Subclinical Cerebrovascular Disease: Epidemiology and Treatment

PURPOSE OF REVIEW

Subclinical cerebrovascular disease (sCVD) is highly prevalent in older adults. The main neuroimaging findings of sCVD include white matter hyperintensities and silent brain infarcts on T2-weighted MRI and cerebral microbleeds on gradient echo or susceptibility-weighted MRI. In this paper, we will review the epidemiology of sCVD, the current evidence for best medical management, and future directions for sCVD research.

RECENT FINDINGS

Numerous epidemiologic studies show that sCVD, in particular WMH, is an important risk factor for the development of dementia, stroke, worse outcomes after stroke, gait instability, late-life depression, and death. Effective treatment of sCVD could have major consequences for the brain health of a substantial portion of older Americans. Despite the link between sCVD and many vascular risk factors, such as hypertension or hyperlipidemia, the optimal medical treatment of sCVD remains uncertain. Given the clinical equipoise about the risk versus benefit of aggressive medical management for sCVD, clinical trials to examine pragmatic, evidence-based approaches to management of sCVD are needed. Such a trial could provide much needed guidance on how to manage a common clinical scenario facing internists and neurologists in practice.

Cerebral microbleeds and stroke risk after ischaemic stroke or transient ischaemic attack: a pooled analysis of individual patient data from cohort studies

BACKGROUND

Cerebral microbleeds are a neuroimaging biomarker of stroke risk. A crucial clinical question is whether cerebral microbleeds indicate patients with recent ischaemic stroke or transient ischaemic attack in whom the rate of future intracranial haemorrhage is likely to exceed that of recurrent ischaemic stroke when treated with antithrombotic drugs. We therefore aimed to establish whether a large burden of cerebral microbleeds or particular anatomical patterns of cerebral microbleeds can identify ischaemic stroke or transient ischaemic attack patients at higher absolute risk of intracranial haemorrhage than ischaemic stroke.

METHODS

We did a pooled analysis of individual patient data from cohort studies in adults with recent ischaemic stroke or transient ischaemic attack. Cohorts were eligible for inclusion if they prospectively recruited adult participants with ischaemic stroke or transient ischaemic attack; included at least 50 participants; collected data on stroke events over at least 3 months follow-up; used an appropriate MRI sequence that is sensitive to magnetic susceptibility; and documented the number and anatomical distribution of cerebral microbleeds reliably using consensus criteria and validated scales. Our prespecified primary outcomes were a composite of any symptomatic intracranial haemorrhage or ischaemic stroke, symptomatic intracranial haemorrhage, and symptomatic ischaemic stroke. We registered this study with the PROSPERO international prospective register of systematic reviews, number CRD42016036602.

FINDINGS

Between Jan 1, 1996, and Dec 1, 2018, we identified 344 studies. After exclusions for ineligibility or declined requests for inclusion, 20 322 patients from 38 cohorts (over 35 225 patient-years of follow-up; median 1·34 years [IQR 0·19-2·44]) were included in our analyses. The adjusted hazard ratio [aHR] comparing patients with cerebral microbleeds to those without was 1·35 (95% CI 1·20-1·50) for the composite outcome of intracranial haemorrhage and ischaemic stroke; 2·45 (1·82-3·29) for intracranial haemorrhage and 1·23 (1·08-1·40) for ischaemic stroke. The aHR increased with increasing cerebral microbleed burden for intracranial haemorrhage but this effect was less marked for ischaemic stroke (for five or more cerebral microbleeds, aHR 4·55 [95% CI 3·08-6·72] for intracranial haemorrhage vs 1·47 [1·19-1·80] for ischaemic stroke; for ten or more cerebral microbleeds, aHR 5·52 [3·36-9·05] vs 1·43 [1·07-1·91]; and for ≥20 cerebral microbleeds, aHR 8·61 [4·69-15·81] vs 1·86 [1·23-1·82]). However, irrespective of cerebral microbleed anatomical distribution or burden, the rate of ischaemic stroke exceeded that of intracranial haemorrhage (for ten or more cerebral microbleeds, 64 ischaemic strokes [95% CI 48-84] per 1000 patient-years vs 27 intracranial haemorrhages [17-41] per 1000 patient-years; and for ≥20 cerebral microbleeds, 73 ischaemic strokes [46-108] per 1000 patient-years vs 39 intracranial haemorrhages [21-67] per 1000 patient-years).

INTERPRETATION

In patients with recent ischaemic stroke or transient ischaemic attack, cerebral microbleeds are associated with a greater relative hazard (aHR) for subsequent intracranial haemorrhage than for ischaemic stroke, but the absolute risk of ischaemic stroke is higher than that of intracranial haemorrhage, regardless of cerebral microbleed presence, antomical distribution, or burden.

FUNDING

British Heart Foundation and UK Stroke Association.

A Follow-up Study of Cerebral Microbleeds in Patients Who Received Stents for Symptomatic Cerebral Artery Stenosis

BACKGROUND

The aims of this study were to explore (i) the dynamic changes in cerebral microbleeds (CMBs) in patients with symptomatic cerebral artery stenosis who received endovascular stent-assisted angioplasty and (ii) the risk factors associated with the new incidence of CMBs as well as whether CMBs increased the risk of vascular events in these patients.

METHODS

Clinical information and magnetic resonance images were collected on admission and 3 months after endovascular stent-assisted angioplasty. Based on susceptibility-weighted imaging, the patients were divided into groups with or without newly developed CMBs, and between-group differences in risk factors were compared. We also compared whether CMBs increased the risk of vascular events among those patients.

RESULTS

Seventy-three patients completed the relevant follow-up examinations. After an average follow-up period of 109 days, 7 (9.6%) patients showed new CMBs. A univariate analysis showed that the number of lacunar infarcts and the increase in systolic blood pressure were higher in patients with new CMBs than in those without new CMBs, and these differences were significant (P = 0.034, P = 0.001). Increased systolic blood pressure was an independent risk factor for developing new CMBs (P = 0.017).

CONCLUSIONS

CMBs may be a continuously progressing cerebral small-vessel disease. The newly developed CMBs in patients with intracranial and/or extracranial stents were associated with increased systolic blood pressure but not with the number of baseline CMBs.

Cerebral Microbleeds and the Safety of Anticoagulation in Ischemic Stroke Patients: A Systematic Review and Meta-Analysis

OBJECTIVES

The objective of this study was to investigate the safety of anticoagulation in ischemic stroke (IS) patients with cerebral microbleeds (CMBs).

METHODS

PubMed, Web of Science, Elsevier Clinical Key, Google Scholar, and Cochrane Library from 1996 to July 2018 were searched to identify relevant studies that included IS patients, underwent T2*-weighted gradient recalled echo, or susceptibility-weighted imaging for detection CMBs and used anticoagulants during follow-up. Primary outcome of interest was intracerebral hemorrhage (ICH). Secondary outcomes were hemorrhage transformation, IS, total mortality, and new developed CMBs. We critically appraised studies and conducted a systematic review and meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance.

RESULTS

We included 7 observational studies. Cerebral microbleeds were associated with a significantly elevated risk of anticoagulation-related ICH (odds ratio, 4.01; 95% confidence interval, 1.82-8.81; P = 0.001). It was significant for warfarin (odds ratio, 8.02; 95% confidence interval, 1.51-42.62; P = 0.015). New developed CMBs in patients on warfarin treatment were associated with baseline CMBs, and the appearance of hemorrhagic transformation did not have a significant relationship with baseline CMBs.

CONCLUSIONS

The presence of CMBs increases the risk of ICH during anticoagulant treatment (especially warfarin) in IS patients. Further studies with larger numbers of patients are needed to confirm our conclusions.

Incident risk and progression of cerebral microbleeds in healthy adults: a multi-occasion longitudinal study

Decline in cerebrovascular health complicates brain aging, and development of cerebral microbleeds (CMBs) is one of its prominent indicators. In a large sample of healthy adults (N = 251, age 18-78 years at baseline, 70% women), the contributions of chronological age and vascular health indicators to the risk of developing a CMB, as well as the change in CMB size and iron content, were examined in a prospective 8-year longitudinal study using susceptibility weighted imaging. Twenty-six persons (10.4%), most of whom were 40 years of age or older, had at least 1 CMB during the study. Older age was associated with greater risk for developing a CMB (odds ratio 1.03). Elevation of combined metabolic syndrome indicators (b = 0.15, p = 0.001) conferred additional risk (odds ratio 1.02). High body mass index exacerbated the risk associated with poor vascular health (b = 0.75, p < 0.001) and frequent exercise mitigated it (b = -0.46, p = 0.03). CMBs persisted over time, yet their volume decreased (mean change = -0.32, p < 0.05), whereas their relative iron content remained stable (mean change = -0.14, p = 0.05). We conclude that although developing a CMB is unlikely during normal aging, risk increases with declining vascular health, which is modifiable via behavioral and pharmaceutical intervention.

Disease progression and regression in sporadic small vessel disease-insights from neuroimaging

Cerebral small vessel disease (SVD) is considered the most important vascular contributor to the development of dementia. Comprehensive characterization of the time course of disease progression will result in better understanding of aetiology and clinical consequences of SVD. SVD progression has been studied extensively over the years, usually describing change in SVD markers over time using neuroimaging at two time points. As a consequence, SVD is usually seen as a rather linear, continuously progressive process. This assumption of continuous progression of SVD markers was recently challenged by several studies that showed regression of SVD markers. Here, we provide a review on disease progression in sporadic SVD, thereby taking into account both progression and regression of SVD markers with emphasis on white matter hyperintensities (WMH), lacunes and microbleeds. We will elaborate on temporal dynamics of SVD progression and discuss the view of SVD progression as a dynamic process, rather than the traditional view of SVD as a continuous progressive process, that might better fit evidence from longitudinal neuroimaging studies. We will discuss possible mechanisms and clinical implications of a dynamic time course of SVD, with both progression and regression of SVD markers.

Anticoagulation for Atrial Fibrillation in Patients with Cerebral Microbleeds

Intracranial haemorrhage (ICH) is the most feared and devastating complication of oral anticoagulation, with high mortality and disability in survivors. Oral anticoagulant-related ICH is increasing in incidence, most likely in part due to the increased use of anticoagulation for atrial fibrillation in the elderly populations with a high prevalence of bleeding-prone cerebral small vessel diseases. Risk scores have been developed to predict bleeding, including ICH, as well as the risk of ischaemic stroke. Recently, attention has turned to brain imaging, in particular, MRI detection of potential prognostic biomarkers, which may help better predict outcomes and individualize anticoagulant decisions. Cerebral microbleeds (CMBs)--small, round areas of signal loss on blood-sensitive MR sequences--have been hypothesized to be a marker for bleeding-prone small vessel pathology, and thus, future symptomatic ICH risk. In this review, we outline the prevalence and prognostic value of CMBs in populations affected by AF for whom anticoagulation decisions are relevant, including healthy older individuals and survivors of ischaemic stroke or ICH. We consider the limitations of currently available evidence, and discuss future research directions in relation to both prognostic markers and treatment options for atrial fibrillation.

Predictors of New Cerebral Microbleeds in Patients with Antiplatelet Drug Therapy

BACKGROUND

Cerebral microbleeds (CMB) are associated with an increased risk for ischemic and especially hemorrhagic stroke. The aim of the present study is to identify patients at high risk for the development of new CMB after initiation of an antiplatelet drug therapy.

METHODS

Patients received magnetic resonance imaging (MRI) within 1 week after initiation of an antiplatelet drug treatment due to a first ischemic stroke (n = 58) and after a follow-up period of 6 months (n = 40). We documented the presence and the number of CMB at baseline and follow-up and analyzed the influence of possible risk factors including vascular risk factors, stroke etiology, and number of CMB at baseline using stepwise logistic regression and Spearman's correlation coefficient. We compared progression rates of CMB in relation to each risk factor using the Mann-Whitney U-test.

RESULTS

The logistic regression model could correctly predict the presence of CMB in 70.7% of patients at baseline and 80% at follow-up. The model correctly identified 85% of patients with new CMB. We observed progression of CMB in 40% of the patients. The overall progression rate was .8 CMB per patient. The progression rate was significantly influenced by age more than 70 years and atherothrombotic stroke. The number of new CMB correlated significantly with the number of CMB at baseline.

CONCLUSIONS

We found several predictors of CMB after initiation of antiplatelet drug therapy. The results help to identify patients who need closer monitoring and thorough control of risk factors in order to lower the risk of new CMB and associated complications.

Incident Cerebral Microbleeds in a Cohort of Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

We aimed to identify prognostic and associated factors of incident cerebral microbleeds (CMBs) in intracerebral hemorrhage (ICH) survivors.

METHODS

Observational prospective cohort of 168 ICH survivors who underwent 1.5T magnetic resonance imaging at ICH onset and during follow-up (median scan interval, 3.4; interquartile range, 1.4-4.7) years. We used logistic regression adjusted for age, sex, and scan interval. Analyses were stratified according to the index ICH location (58 lobar ICH, 103 nonlobar ICH, excluding patients with multiple or unclassifiable ICH).

RESULTS

Eighty-nine (53%) patients had CMBs at ICH onset, and 80 (48%) exhibited incident CMBs during follow-up. Predictors of incident CMBs at ICH onset were ≥1 CMBs (adjusted odds ratio [aOR], 2.27; 95% confidence interval [CI], 1.18-4.35), old radiological macrohemorrhage (aOR, 6.78; 95% CI, 2.76-16.68), and CMBs in mixed location (aOR, 3.73; 95% CI, 1.67-8.31). When stratifying by ICH location, incident CMBs were associated in nonlobar ICH with incident lacunes (aOR, 2.86; 95% CI, 1.04-7.85) and with the use of antiplatelet agents (aOR, 2.89; 95% CI, 1.14-7.32). In lobar ICH, incident CMBs were associated with incident radiological macrohemorrhage (aOR, 9.76; 95% CI, 1.07-88.77).

CONCLUSIONS

Prognostic and associated factors of incident CMBs differed according to the index ICH location. Whereas in lobar ICH, incident CMBs were associated with hemorrhagic biomarkers, in nonlobar ICH, ischemic burden also increased. CMBs may be interesting biomarkers to monitor in randomized trials on restarting antithrombotic drugs after ICH.

New Cerebral Microbleeds After Mechanical Thrombectomy for Large-Vessel Occlusion Strokes

The interval appearance of cerebral microbleeds (CMBs) after endovascular treatment has never been described. We investigated the frequency and predictors of new CMBs that developed shortly after mechanical thrombectomy for acute ischemic stroke, and its impact on clinical outcome.We retrospectively analyzed patients with large-vessel occlusion strokes treated with Merci Retriever, Penumbra System, or stent-retriever devices. Serial T2*-weighted gradient-recall echo (GRE) magnetic resonance imaging (MRI) before and 48 h after endovascular thrombectomy were assessed to identify new CMBs. We examined independent factors associated with new CMBs after mechanical thrombectomy. We analyzed the association of the presence, burden, and distribution of new CMBs with clinical outcome.A total of 187 consecutive patients with serial GRE were enrolled in this study. CMBs were evident in 36 (19.3%) patients before mechanical thrombectomy. New CMBs occurred in 41 (21.9%) patients after mechanical thrombectomy. Of the 68 new CMBs, 45 appeared in the lobar location, 18 in the deep location and 5 in the infratentorial location. The presence of baseline CMBs was associated with new CMBs after mechanical thrombectomy (OR 5.38; 95% CI 2.13-13.59; P < 0.001), no matter whether the patients were treated primarily with mechanical thrombectomy or with intravenous thrombolysis followed by mechanical thrombectomy. Patients with new CMBs did not have increased rates of hemorrhagic transformation, in-hospital mortality, and modified Rankin Scale score 4 to 6 at discharge.New CMBs are common after mechanical thrombectomy in one-fifth of patients with acute ischemic stroke. Baseline CMBs before mechanical thrombectomy predicts the development of new CMBs. New CMBs after mechanical thrombectomy do not influence clinical outcome.

Silent New Brain Lesions: Innocent Bystander or Guilty Party?

With the advances in magnetic resonance imaging, previously unrecognized small brain lesions, which are mostly asymptomatic, have been increasingly detected. Diffusion-weighted imaging can identify small ischemic strokes, while gradient echo T2* imaging and susceptibility-weighted imaging can reveal tiny hemorrhagic strokes (microbleeds). In this article, we review silent brain lesions appearing soon after acute stroke events, including silent new ischemic lesions and microbleeds appearing 1) after acute ischemic stroke and 2) after acute intracerebral hemorrhage. Moreover, we briefly discuss the clinical implications of these silent new brain lesions.

Quantity of Cerebral Microbleeds, Antiplatelet Therapy, and Intracerebral Hemorrhage Outcomes: A Systematic Review and Meta-analysis

BACKGROUND AND PURPOSE

Cerebral microbleeds (CMBs) increase future intracerebral hemorrhage (ICH) risk after ischemic stroke (IS) or transient ischemic attack (TIA). However, whether CMB-related ICH risk depends on CMB quantity, CMB location, or antithrombotic agents is unclear. We performed a systematic review and meta-analysis to investigate CMB-related ICH risk, stratifying patients according to the quantity of CMB, the location of CMB, and the type of antithrombotic therapy used.

METHODS

Literature databases were searched for prospective cohorts reporting ICH outcomes in patients with IS or TIA with baseline CMB evaluation. We calculated pooled relative ratios (RRs) for ICH among patients with and without CMBs. Pooled RRs of CMB-related ICH were further calculated in subgroups stratified by CMB quantity, CMB location, and antithrombotic therapy.

RESULTS

Among the 10 included studies, the pooled RR of future ICH was 7.73 (95% confidence interval [CI], 4.07-14.70; P < .001) in CMB versus non-CMB patients. Subgroup analysis revealed that compared with non-CMB patients, multiple-CMB patients were at an increased risk for future ICH (RR = 8.02; 95% CI, 3.21-20.01; P < .001), whereas single-CMB patients did not incur this risk (RR = 2.33; 95% CI, .63-8.63; P = .205). A strong association was found between CMB presence and subsequent ICH in antiplatelet users (RR = 16.56; 95% CI, 3.68-74.42; P < .001). Studies on CMB-related ICH according to CMB locations and in anticoagulant users are lacking for subgroup analysis.

CONCLUSION

Our study revealed that patients with IS or TIA with multiple CMBs may incur a higher risk of future ICH, and the presence of CMBs in patients with IS or TIA using antiplatelet agents may significantly increase the subsequent ICH risk.

Cerebral Microbleeds Are Associated With an Increased Risk of Stroke: The Rotterdam Study

BACKGROUND

Cerebral microbleeds are highly prevalent in people with clinically manifest cerebrovascular disease and have been shown to increase the risk of stroke recurrence. Microbleeds are also frequently found in healthy elderly, a population in which the clinical implication of microbleeds is unknown.

METHODS AND RESULTS

In the population-based Rotterdam Study, the presence, number, and location of microbleeds were assessed at baseline on brain MRI of 4759 participants aged ≥45 years. Participants were followed for incident stroke throughout the study period (2005-2013). We used Cox proportional hazards to investigate if people with microbleeds were at increased risk of stroke in comparison with those without microbleeds, adjusting for demographic, genetic, and cardiovascular risk, and cerebrovascular imaging markers. Microbleed prevalence was 18.7% (median count 1 [1-111]). During mean follow-up of 4.9 years (standard deviation, 1.6) 93 strokes occurred (72 ischemic, 11 hemorrhagic, and 10 unspecified). Microbleed presence was associated with an increased risk of all strokes (hazard ratio, 1.93; 95% confidence interval, 1.25-2.99). The risk increased with greater microbleed count. In comparison with those without microbleeds, participants with microbleeds in locations suggestive of cerebral amyloid angiopathy (lobar with or without cerebellar microbleeds) were at increased risk of intracerebral hemorrhage (hazard ratio, 5.27; 95% confidence interval, 1.38-20.23). Microbleeds at other locations were associated with an increased risk of both ischemic stroke and intracerebral hemorrhage.

CONCLUSIONS

Microbleeds on MRI are associated with an increased risk of stroke in the general population. Our results strengthen the notion that microbleeds mark progression of cerebrovascular pathology and represent a precursor of stroke.

Prevention and Management of Cerebral Small Vessel Disease

Lacunar infarcts/lacunes, white matter hyperintensities (WMH), and cerebral microbleeds (CMBs) are considered various manifestations of cerebral small vessel disease (SVD). Since the exact mechanisms of these manifestations differ, their associated risk factors differ. High blood pressure is the most consistent risk factor for all of these manifestations. However, a "J curve" phenomenon in terms of blood pressure probably exists for WMH. The association between cholesterol levels and lacunar infarcts/lacunes or WMH was less consistent and sometimes conflicting; a low cholesterol level probably increases the risk of CMBs. Homocysteinemia appears to be associated with WMH. It is noteworthy that the risk factors profile may also differ between different lacunar patterns and CMBs located at different parts of the brain. Thrombolysis, antihypertensives, and statins are used to treat patients with symptomatic lacunar infarction, just as in those with other stroke subtypes. However, it should be remembered that bleeding risks increase in patients with extensive WMH and CMBs after thrombolysis therapy. According to the Secondary Prevention of Small Subcortical Strokes trial results, a blood pressure reduction to <130 mmHg is recommended in patients with symptomatic lacunar infarction. However, an excessive blood pressure decrease may induce cognitive decline in older patients with extensive WMH. Dual antiplatelet therapy (aspirin plus clopidogrel) should be avoided because of the excessive risk of intracerebral hemorrhage. Although no particular antiplatelet is recommended, drugs such as cilostazol or triflusal may have advantages for patients with SVD since they are associated with less frequent bleeding complications than aspirin.

Cerebral microbleeds as a predictor of macrobleeds: what is the evidence?

Cerebral microbleeds on blood-sensitive magnetic resonance imaging sequences have emerged as a common and important marker of small vessel disease. Cerebral microbleeds differ from other imaging manifestations of small vessel disease (e.g. lacunes and leukoaraiosis), as they seem to provide more direct evidence of microvascular leakiness from bleeding-prone arteriopathies, namely hypertensive arteriopathy and cerebral amyloid angiopathy, the two leading causes of spontaneous intracerebral haemorrhage. Thus, cerebral microbleeds in specific sub-populations might provide evidence of an ongoing active small vessel arteriopathy with increased future risk of symptomatic intracerebral haemorrhage ('macrobleeding'). If this hypothesis is correct, it raises clinical dilemmas especially regarding the safety of antithrombotic drug use. Although data so far are limited, the relationship of microbleeds to future macrobleeding (and cerebral ischemia) seems to critically depend on the specific patient population and cerebral microbleeds location and burden, which may reflect the nature and severity of the underlying arteriopathies.

Progression of brain microbleeds in essential hypertensive patients: a 2-year follow-up study

BACKGROUND

Brain microbleeds (BMBs) are common in hypertensive patients and are associated with higher blood pressure (BP) levels. Little is known about risk factors for progression of BMBs, in particular the contribution of ambulatory BP levels. We aimed to determine BMB progression and the association with BP levels in a cohort of essential hypertensive patients.

METHODS

At baseline and after 2 years of follow-up, 193 participants underwent brain magnetic resonance imaging (MRI) and 24-hour ambulatory BP measurement in addition to office BP measurement. The relation between BMB progression and baseline untreated BP characteristics was tested in logistic regression analyses.

RESULTS

Progression of BMBs on follow-up MRI was seen in 12 (6%) participants. Patients with progression were significantly older, and the prevalence as well as total number of BMBs at baseline was greater. With correction for age and sex, baseline 24-hour systolic and diastolic BP and 24-hour pulse pressure significantly predicted progression. Similar results were seen for baseline awake and asleep BP. On additional adjustments for baseline presence of BMBs, the associations remained significant for 24-hour, awake, and asleep systolic BP, awake diastolic BP, and awake and asleep pulse pressure. Office systolic BP was also associated with progression of BMBs, whereas office diastolic BP was not.

CONCLUSIONS

High ambulatory BP levels are important and possibly modifiable predictors for progression of BMBs. This warrants further study, with an adequately long follow-up period and early adequate treatment of hypertension.

Cerebral microbleeds: overview and implications in cognitive impairment

Cerebral microbleeds (MBs) are small chronic brain hemorrhages which are likely caused by structural abnormalities of the small vessels of the brain. Owing to the paramagnetic properties of blood degradation products, MBs can be detected in vivo by using specific magnetic resonance imaging (MRI) sequences. Over the last decades, the implementation of these MRI sequences in both epidemiological and clinical studies has revealed MBs as a common finding in many different populations, including healthy individuals. Also, the topographic distribution of these MBs has been shown to be potentially associated with specific underlying vasculopathies. However, the clinical and prognostic significance of these small hemorrhages is still a matter of debate as well as a focus of extensive research. In this article, we aim to review the current knowledge on the pathophysiology and clinical implications of MBs, with special emphasis on the links between lobar MBs, cerebral amyloid angiopathy, and Alzheimer’s disease.

Cerebral microbleeds: a review of clinical, genetic, and neuroimaging associations

Cerebral microbleeds (microbleeds) are small, punctuate hypointense lesions seen in T2* Gradient-Recall Echo (GRE) and Susceptibility-Weighted (SWI) Magnetic Resonance Imaging (MRI) sequences, corresponding to areas of hemosiderin breakdown products from prior microscopic hemorrhages. They occur in the setting of impaired small vessel integrity, commonly due to either hypertensive vasculopathy or cerebral amyloid angiopathy. Microbleeds are more prevalent in individuals with Alzheimer’s disease (AD) dementia and in those with both ischemic and hemorrhagic stroke. However they are also found in asymptomatic individuals, with increasing prevalence with age, particularly in carriers of the Apolipoprotein (APOE) ε4 allele. Other neuroimaging findings that have been linked with microbleeds include lacunar infarcts and white matter hyperintensities on MRI, and increased cerebral β-amyloid burden using ¹¹C-PiB Positron Emission Tomography. The presence of microbleeds has been suggested to confer increased risk of incident intracerebral hemorrhage – particularly in the setting of anticoagulation – and of complications of immunotherapy for AD. Prospective data regarding the natural history and sequelae of microbleeds are currently limited, however there is a growing evidence base that will serve to inform clinical decision-making in the future.

Cerebral microbleeds: their associated factors, radiologic findings, and clinical implications

Cerebral microbleeds (CMBs) are tiny, round dark-signal lesions that are most often detected on gradient-echo MR images. CMBs consist of extravasations of blood components through fragile microvascular walls characterized by lipohyalinosis and surrounding macrophages. The prevalence of CMBs in elderly subjects with no history of cerebrovascular disease is around 5%, but is much higher in patients with ischemic or hemorrhagic stroke. Development of CMBs is closely related to various vascular risk factors; in particular, lobar CMBs are thought to be associated with cerebral amyloid angiopathy. The presence of CMBs has been hypothesized to reflect cerebral-hemorrhage-prone status in patients with hypertension or amyloid microangiopathy. Stroke survivors with CMBs have been consistently found to have an elevated risk of subsequent hemorrhagic stroke or an antithrombotic-related hemorrhagic complication, although studies have failed to establish a link between CMBs and hemorrhagic transformation after thrombolytic treatment. A large prospective study is required to clarify the clinical significance of CMBs and their utility in a decision-making index.

Key neuroanatomical structures for post-stroke cognitive impairment

The neuroanatomical substrate of vascular cognitive impairment (VCI) has traditionally included the subcortex of the brain, especially sub-frontal white matter circuits, strategic areas of single infarction that may mediate cognitive impairment such as the dominant thalamus or angular gyrus, and the left hemisphere, and bilateral brain infarcts or volume-driven cortical-subcortical infarctions reaching a critical threshold of tissue loss or injury. We provide an update on the neuroanatomical substrates of VCI and emphasize the following structures or areas: (1) new concepts in relation to hippocampal involvement in VCI based on neuropathological and MRI studies of microinfarcts and the role of traditional cardiovascular risk factors in possibly mediating or potentiating cognitive impairment; (2) advances in our understanding of cerebral microbleeds; and (3) an update on white matter hyperintensities and small vessel disease.

Sequence-specific MR imaging findings that are useful in dating ischemic stroke

Patients may present to the hospital at various times after an ischemic stroke. Many present weeks after a neurologic deficit has occurred, as is often the case with elderly patients and those in a nursing home. The ability to determine the age of an ischemic stroke provides useful clinical information for the patient, his or her family, and the medical team. Many times, perfusion imaging is not performed, and pulse sequence-specific magnetic resonance (MR) imaging findings may help determine the age of the infarct. The findings seen at apparent diffusion coefficient mapping and diffusion-weighted, fluid-attenuated inversion recovery (FLAIR) and unenhanced and contrast material-enhanced T1- and T2-weighted gradient-echo and susceptibility-weighted MR imaging may help determine the relative age of a cerebral infarct. Strokes may be classified and dated as early hyperacute, late hyperacute, acute, subacute, or chronic. Recent data indicate that in many patients with restricted diffusion and no change on FLAIR images, it is more likely than was initially thought that the stroke is less than 6 hours old. The time window to administer intravenous tissue plasminogen activator is currently 4.5 hours from the time when the patient was last seen to be normal, and for anterior circulation strokes, the time window for administering intraarterial tissue plasminogen activator is 6 hours from when the patient was last seen to be normal. For this reason, accurate dating is important in patients with ischemic stroke.

Higher ambulatory blood pressure relates to new cerebral microbleeds: 2-year follow-up study in lacunar stroke patients

BACKGROUND AND PURPOSE

Elevated blood pressure (BP) is associated with the presence of cerebral microbleeds (CMBs) in cross-sectional studies. However, longitudinal studies did not show a convincing relationship. We aimed to determine the association between elevated BP levels and the occurrence of new CMBs after a 2-year follow-up in first-ever lacunar stroke patients using ambulatory BP monitoring.

METHODS

Ninety-six first-ever lacunar stroke patients underwent brain MRI and ambulatory BP monitoring at baseline and after 2-year follow-up. We used logistic regression analyses to assess the association of BP levels with new CMBs.

RESULTS

We found new CMBs in 17 patients (18%). Higher 24-hour, day and night systolic BP (odds ratio, 2.69; 95% confidence interval, 1.40-5.21 per SD increase for 24-hour BP) and diastolic BP (odds ratio, 2.13; 95% confidence interval, 1.15-3.90 per SD increase for 24-hour BP) at baseline were associated with the development of new CMBs independent of age and sex. BP levels decreased during follow-up in both patients with and without new CMBs. Unlike BP levels at baseline, there was no difference in BP levels at follow-up between patients with and without new CMBs.

CONCLUSIONS

Both higher systolic and diastolic BP levels were associated with the development of new CMBs in a population of lacunar stroke patients. Decrease of BP levels during follow-up did not halt progression of CMBs; however, it remains to be determined whether (early) intervention with antihypertensive drugs can slow down progression of CMBs.