Association of enlarged perivascular spaces and anticoagulant-related intracranial hemorrhage

Cortical Microhemorrhage Presentation of Small Vessel Primary Angiitis of the Central Nervous System

OBJECTIVE

Primary angiitis of the central nervous system (PACNS) is a rare vasculitis restricted to the brain, spinal cord, and leptomeninges. This study aimed to describe the imaging characteristics of patients with small vessel PACNS (SV-PACNS) using 7 T magnetic resonance imaging (MRI).

METHODS

This ongoing prospective observational cohort study included patients who met the Calabrese and Mallek criteria and underwent 7 T MRI scan. The MRI protocol includes T1-weighted magnetization-prepared rapid gradient echo imaging, T2 star weighted imaging, and susceptibility-weighted imaging. Two experienced readers independently reviewed the neuroimages. Clinical data were extracted from the electronic patient records. The findings were then applied to a cohort of patients with large vessel central nervous system (CNS) vasculitis.

RESULTS

We included 21 patients with SV-PACNS from December 2021 to November 2023. Of these, 12 (57.14%) had cerebral cortical microhemorrhages with atrophy. The pattern with microhemorrhages was described in detail based on the gradient echo sequence, leading to the identification of what we have termed the "coral-like sign." The onset age of patients with coral-like sign (33.83 ± 9.93 years) appeared younger than that of patients without coral-like sign (42.11 ± 14.18 years) (P = 0.131). Furthermore, the cerebral lesions in patients with cortical microhemorrhagic SV-PACNS showed greater propensity toward bilateral lesions (P = 0.03). The coral-like sign was not observed in patients with large vessel CNS vasculitis.

INTERPRETATION

The key characteristics of the coral-like sign represent cerebral cortical diffuse microhemorrhages with atrophy, which may be an important MRI pattern of SV-PACNS. ANN NEUROL 2024;96:194-203.

Left atrial appendage closure for patients with atrial fibrillation at high intracranial haemorrhagic risk

BACKGROUND AND OBJECTIVES

Although left atrial appendage closure (LAAC) is performed in patients with non-valvular atrial fibrillation (NVAF) at increased risk of intracranial haemorrhage (ICH), outcome data are scarce. We assessed the detailed neurological indications for LAAC and outcomes after LAAC in high ICH risk patients.

METHODS

Study population included consecutive patients with NVAF who underwent LAAC in a single hospital network between January 2015 and October 2021 because of prior ICH or the presence of high ICH risk imaging markers on brain MRI (cerebral microbleeds (CMBs)). Primary safety and efficacy outcome measures were the occurrence of ICH and thromboembolic events, respectively, after LAAC.

RESULTS

Among 146 patients with NVAF who underwent LAAC for high ICH risk, 122 had a history of ICH, while 24 presented with high ICH risk imaging markers only. Mean age was 75.7±7.61, 42 (28.8%) were women. Mean CHA2DS2-VASc score was 5.23±1.52. Of 122 patients with ICH history, 58 (47.5%) had intraparenchymal haemorrhage (IPH), 40 (32.8%) had traumatic ICH (T-ICH) and 18 (14.7%) had non-traumatic subdural haemorrhage. Of 85 patients with brain MRIs including necessary sequences, 43 (50.6%) were related to cerebral amyloid angiopathy and 37 (43.5%) to hypertensive microangiopathy. While 70% of patients were discharged on oral anticoagulants (OAC), 92% were not taking OAC at 1 year. Over 2.12 years mean follow-up, one patient had recurrent non-traumatic IPH (incidence rate (IR) 0.32 per 100 patient-years), five had T-ICH (IR 1.61 per 100 patient-years) and six had an ischaemic stroke (IR 1.94 per 100 patient-years).

CONCLUSIONS

Among patients with NVAF at high ICH risk, LAAC demonstrated a low risk of recurrent ICH or ischaemic stroke compared with previously published data. LAAC in high ICH risk populations should be considered in clinical practice per FDA approval and recent guidelines.

Differential risk factor profile and neuroimaging markers of small vessel disease between lacunar ischemic stroke and deep intracerebral hemorrhage

Background

Lacunar ischemic stroke (LIS) and deep intracerebral hemorrhage (dICH) are two stroke phenotypes of deep perforator arteriopathy. It is unclear what factors predispose individuals with deep perforator arteriopathy to either ischemic or hemorrhagic events.

Objectives

We aimed to investigate risk factors and neuroimaging features of small vessel disease (SVD) associated with LIS versus dICH in a cross-sectional study.

Methods

We included patients with clinically presenting, magnetic resonance imaging-confirmed LIS or dICH from two tertiary hospitals between 2010 and 2021. We recorded vascular risk factors and SVD markers, including lacunes, white matter hyperintensities (WMH), perivascular spaces (PVS), and cerebral microbleeds (CMB). Logistic regression modeling was used to determine the association between vascular risk factors, SVD markers, and stroke phenotype. We further created WMH probability maps to compare WMH distribution between LIS and dICH.

Results

A total of 834 patients with LIS (mean age 61.7 ± 12.1 years) and 405 with dICH (57.7 ± 13.2 years) were included. Hypertension was equally frequent between LIS and dICH (72.3% versus 74.8%, p = 0.349). Diabetes mellitus, hyperlipidemia, smoking, and prior ischemic stroke were more associated with LIS [odds ratio (OR) (95% confidence interval (CI)), 0.35 (0.25-0.48), 0.32 (0.22-0.44), 0.31 (0.22-0.44), and 0.38 (0.18-0.75)]. Alcohol intake and prior ICH were more associated with dICH [OR (95% CI), 2.34 (1.68-3.28), 2.53 (1.31-4.92)]. Lacunes were more prevalent in LIS [OR (95% CI) 0.23 (0.11-0.43)], while moderate-to-severe basal-ganglia PVS and CMB were more prevalent in dICH [OR (95% CI) 2.63 (1.35-5.27), 4.95 (2.71-9.42)]. WMH burden and spatial distribution did not differ between groups.

Conclusion

The microangiopathy underlying LIS and dICH reflects distinct risk profiles and SVD features, hence possibly SVD subtype susceptibility. Prospective studies with careful phenotyping and genetics are needed to clarify the mechanisms underlying this difference.

Cerebral Small Vessel Disease Burden for Bleeding Risk during Antithrombotic Therapy: Bleeding with Antithrombotic Therapy 2 Study

OBJECTIVE

This study was undertaken to determine the excess risk of antithrombotic-related bleeding due to cerebral small vessel disease (SVD) burden.

METHODS

In this observational, prospective cohort study, patients with cerebrovascular or cardiovascular diseases taking oral antithrombotic agents were enrolled from 52 hospitals across Japan between 2016 and 2019. Baseline multimodal magnetic resonance imaging acquired under prespecified conditions was assessed by a central diagnostic radiology committee to calculate total SVD score. The primary outcome was major bleeding. Secondary outcomes included bleeding at each site and ischemic events.

RESULTS

Of the analyzed 5,250 patients (1,736 women; median age = 73 years, 9,933 patient-years of follow-up), antiplatelets and anticoagulants were administered at baseline in 3,948 and 1,565, respectively. Median SVD score was 2 (interquartile range = 1-3). Incidence rate of major bleeding was 0.39 (per 100 patinet-years) in score 0, 0.56 in score 1, 0.91 in score 2, 1.35 in score 3, and 2.24 in score 4 (adjusted hazard ratio [aHR] for score 4 vs 0 = 5.47, 95% confidence interval [CI] = 2.26-13.23), that of intracranial hemorrhage was 0.11, 0.33, 0.58, 0.99, and 1.06, respectively (aHR = 9.29, 95% CI = 1.99-43.35), and that of ischemic event was 1.82, 2.27, 3.04, 3.91, and 4.07, respectively (aHR = 1.76, 95% CI = 1.08-2.86). In addition, extracranial major bleeding (aHR = 3.43, 95% CI = 1.13-10.38) and gastrointestinal bleeding (aHR = 2.54, 95% CI = 1.02-6.35) significantly increased in SVD score 4 compared to score 0.

INTERPRETATION

Total SVD score was predictive for intracranial hemorrhage and probably for extracranial bleeding, suggesting the broader clinical relevance of cerebral SVD as a marker for safe implementation of antithrombotic therapy. ANN NEUROL 2024;95:774-787.

Clinical features and associated factors of coexisting intracerebral hemorrhage in patients with cerebral small vessel disease: a cross-sectional study

Intracerebral hemorrhage (ICH) is generally considered to be closely related to cerebral small vessel disease (CSVD), leading to a poor prognosis. However, the coexistence of ICH in general CSVD patients and related factors remain underreported. In our cross-sectional study, we screened 414 CSVD patients from a database at the Department of Neurology, First Affiliated Hospital of Zhengzhou University (September 2018 to April 2022). Imaging biomarkers of CSVD and coexisting ICH lesion were assessed. Factors associated with coexisting ICH in CSVD were determined using multivariate logistic regression analysis. ICH was observed in 59 patients (14.3%). Multivariate logistic regression showed that previous history of ischemic stroke or transient ischemic attack (OR 5.189, 95%CI 2.572-10.467, P < 0.001), high-grade perivascular space in the basal ganglia (n > 10) (OR 2.051, 95%CI 1.044-4.027, P = 0.037) and low adjusted calcium-phosphorus product (OR 0.728 per 1 [mmol/L]2 increase, 95%CI 0.531-0.998, P = 0.049) were associated with coexisting ICH in CSVD patients. The considerable proportion of coexisting ICH and revelation of associated factors in general CSVD patients alert physicians of the potential risk of the reoccurrence of ICH, and might have a significant impact on therapeutic strategies.

In patients who had a stroke or TIA, enlarged perivascular spaces in basal ganglia may cause future haemorrhagic strokes

INTRODUCTION

It remains unclear whether enlarged perivascular spaces (EPVS) predict poor clinical outcomes in patients with acute ischaemic stroke (AIS) or transient ischaemic attack (TIA).

METHOD

Data were obtained from the Third China National Stroke Registry study. We estimated EPVS in basal ganglia (BG) and centrum semiovale (CSO) using a semiquantified scale (Grade from 0 to 4). Using Cox and logistic regression analyses, the associations of EPVS with 3-month and 1-year adverse outcomes (including recurrent stroke, ischaemic stroke, haemorrhagic stroke, combined vascular event, disability and mortality) were explored. Sensitivity analyses of any association of cerebral small vessel disease at baseline and development of a small arterial occlusion (SAO) were conducted.

RESULT

Among 12 603 patients with AIS/TIA, median age was 61.7±11.6 years, and 68.2% were men. After adjusting for all potential confounders, frequent-to-severe BG-EPVS was associated with a decreased risk of recurrent ischaemic stroke (HR 0.71, 95% CI 0.55 to 0.92, p=0.01) but an increased risk of haemorrhagic stroke (HR 1.99, 95% CI 1.11 to 3.58, p=0.02) at 1 year after AIS/TIA, compared with none-to-mild BG-EPVS. Patients with frequent-to-severe CSO-EPVS had a decreased risk of disability (OR 0.76, 95% CI 0.62 to 0.92, p=0.004) and all-cause death (HR 0.55, 95% CI 0.31 to 0.98, p=0.04) within 3-month but not 1-year follow-ups, compared with those with none-to-mild BG-EPVS. Sensitivity analyses showed that both BG-EPVS (HR 0.43, 95% CI 0.21 to 0.87, p=0.02) and CSO-EPVS (HR 0.58, 95% CI 0.35 to 0.95, p=0.03) were associated with a decreased risk of subsequent ischaemic stroke in patients with SAO during 1-year follow-up.

CONCLUSION

BG-EPVS increased the risk of haemorrhagic stroke in patients already with AIS/TIA within 1 year. Therefore, caution is recommended when selecting antithrombotic agents for secondary stroke prevention in patients with AIS/TIA and more severe BG-EPVS.

Clinical Associations and Prognostic Value of MRI-Visible Perivascular Spaces in Patients With Ischemic Stroke or TIA: A Pooled Analysis

BACKGROUND AND OBJECTIVES

Visible perivascular spaces are an MRI marker of cerebral small vessel disease and might predict future stroke. However, results from existing studies vary. We aimed to clarify this through a large collaborative multicenter analysis.

METHODS

We pooled individual patient data from a consortium of prospective cohort studies. Participants had recent ischemic stroke or transient ischemic attack (TIA), underwent baseline MRI, and were followed up for ischemic stroke and symptomatic intracranial hemorrhage (ICH). Perivascular spaces in the basal ganglia (BGPVS) and perivascular spaces in the centrum semiovale (CSOPVS) were rated locally using a validated visual scale. We investigated clinical and radiologic associations cross-sectionally using multinomial logistic regression and prospective associations with ischemic stroke and ICH using Cox regression.

RESULTS

We included 7,778 participants (mean age 70.6 years; 42.7% female) from 16 studies, followed up for a median of 1.44 years. Eighty ICH and 424 ischemic strokes occurred. BGPVS were associated with increasing age, hypertension, previous ischemic stroke, previous ICH, lacunes, cerebral microbleeds, and white matter hyperintensities. CSOPVS showed consistently weaker associations. Prospectively, after adjusting for potential confounders including cerebral microbleeds, increasing BGPVS burden was independently associated with future ischemic stroke (versus 0-10 BGPVS, 11-20 BGPVS: HR 1.19, 95% CI 0.93-1.53; 21+ BGPVS: HR 1.50, 95% CI 1.10-2.06; p = 0.040). Higher BGPVS burden was associated with increased ICH risk in univariable analysis, but not in adjusted analyses. CSOPVS were not significantly associated with either outcome.

DISCUSSION

In patients with ischemic stroke or TIA, increasing BGPVS burden is associated with more severe cerebral small vessel disease and higher ischemic stroke risk. Neither BGPVS nor CSOPVS were independently associated with future ICH.

Glymphatic system: an emerging therapeutic approach for neurological disorders

The functions of the glymphatic system include clearance of the metabolic waste and modulation of the water transport in the brain, and it forms a brain-wide fluid network along with cerebrospinal fluid (CSF) and interstitial fluid (ISF). The glymphatic pathway consists of periarterial influx of CSF, astrocyte-mediated interchange between ISF and CSF supported by aquaporin-4 (AQP4) on the endfeet of astrocyte around the periarterioles, and perivenous efflux of CSF. Finally, CSF is absorbed by the arachnoid granules or flows into the cervical lymphatic vessels. There is growing evidence from animal experiments that the glymphatic system dysfunction is involved in many neurological disorders, such as Alzheimer's disease, stroke, epilepsy, traumatic brain injury and meningitis. In this review, we summarize the latest progress on the glymphatic system and its driving factors, as well as changes in the glymphatic pathway in different neurological diseases. We significantly highlight the likely therapeutic approaches for glymphatic pathway in neurological diseases, and the importance of AQP4 and normal sleep architecture in this process.

Risk Factors for Anticoagulant-Associated Intracranial Hemorrhage: A Systematic Review and Meta-analysis

BACKGROUND

Anticoagulant-associated intracranial hemorrhage has a high mortality rate, and many factors can cause intracranial hemorrhage. Until now, systematic reviews and assessments of the certainty of the evidence have not been published.

METHODS

We conducted a systematic review to identify risk factors for anticoagulant-associated intracranial hemorrhage. The protocol for this systematic review was prospectively registered with PROSPERO (CRD42022316750). All English studies that met the inclusion criteria published before January 2022 were obtained from PubMed, EMBASE, Web of Science, and Cochrane Library. Two researchers independently screened articles, extracted data, and evaluated the quality and evidence of the included studies. Risk factors for intracranial hemorrhage were used as the outcome index of this review. Random or fixed-effect models were used in statistical methods. I2 statistics were used to evaluate heterogeneity.

RESULTS

Of 7322 citations, we included 20 studies in our analysis. For intracranial hemorrhage, moderate-certainty evidence showed a probable association with race, Glasgow Coma Scale, stroke, leukoaraiosis, cerebrovascular disease, tumor, atrial fibrillation, previous bleeding, international normalized ratio, serum albumin, prothrombin time, diastolic blood pressure, and anticoagulant. Low-certainty evidence may be associated with age, cerebral microbleeds, smoking, alcohol intake, platelet count, and antiplatelet drug. In addition, we found very low-certainty evidence that there may be little to no association between the risk of intracranial hemorrhage and hypertension and creatinine clearance. Leukoaraiosis, cerebral microbleeds, cerebrovascular disease, and international normalized ratio are not included in most risk assessment models.

CONCLUSIONS

This study informs risk prediction for anticoagulant-associated intracranial hemorrhage and informs guidelines for intracranial hemorrhage prevention and future research.

Magnetic resonance imaging of white matter in Alzheimer's disease: a global bibliometric analysis from 1990 to 2022

Background

Alzheimer's disease (AD) is a common, progressive, irreversible, and fatal neurodegenerative disorder with rapidly increasing worldwide incidence. Although much research on magnetic resonance imaging (MRI) of the white matter (WM) in AD has been published, no bibliometric analysis study has investigated this issue. Thus, this study aimed to provide an overview of the current status, hotspots, and trends in MRI of WM in AD.

Methods

We searched for records related to MRI studies of WM in AD from 1990 to 2022 in the Web of Science Core Collection (WOSCC) database. CiteSpace (version 5.1.R8) and VOSviewer (version 1.6.19) software were used for bibliometric analyses.

Results

A total of 2,199 articles were obtained from this study. From 1990 to 2022, the number of published articles showed exponential growth of y = 4.1374e^0.1294x, with an average of 17.9 articles per year. The top country and institutions were the United States and the University of California Davis, accounting for 44.52 and 5.32% of the total studies, respectively. The most productive journal was Neurology, and the most co-cited journal was Lancet Neurology. Decarli C was the most productive author. The current research frontier trend focuses on the association between small vessel disease and AD, the clinical application and exploration of diffusion MRI, and related markers.

Conclusion

This study provides an in-depth overview of publications on MRI of WM in AD, identifying the current research status, hotspots, and frontier trends in the field.

The etiology and evolution of magnetic resonance imaging-visible perivascular spaces: Systematic review and meta-analysis

Objectives

Perivascular spaces have been involved in neuroinflammatory and neurodegenerative diseases. Upon a certain size, these spaces can become visible on magnetic resonance imaging (MRI), referred to as enlarged perivascular spaces (EPVS) or MRI-visible perivascular spaces (MVPVS). However, the lack of systematic evidence on etiology and temporal dynamics of MVPVS hampers their diagnostic utility as MRI biomarker. Thus, the goal of this systematic review was to summarize potential etiologies and evolution of MVPVS.

Methods

In a comprehensive literature search, out of 1,488 unique publications, 140 records assessing etiopathogenesis and dynamics of MVPVS were eligible for a qualitative summary. 6 records were included in a meta-analysis to assess the association between MVPVS and brain atrophy.

Results

Four overarching and partly overlapping etiologies of MVPVS have been proposed: (1) Impairment of interstitial fluid circulation, (2) Spiral elongation of arteries, (3) Brain atrophy and/or perivascular myelin loss, and (4) Immune cell accumulation in the perivascular space. The meta-analysis in patients with neuroinflammatory diseases did not support an association between MVPVS and brain volume measures [R: −0.15 (95%-CI −0.40–0.11)]. Based on few and mostly small studies in tumefactive MVPVS and in vascular and neuroinflammatory diseases, temporal evolution of MVPVS is slow.

Conclusion

Collectively, this study provides high-grade evidence for MVPVS etiopathogenesis and temporal dynamics. Although several potential etiologies for MVPVS emergence have been proposed, they are only partially supported by data. Advanced MRI methods should be employed to further dissect etiopathogenesis and evolution of MVPVS. This can benefit their implementation as an imaging biomarker.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=346564, identifier CRD42022346564.

Cerebral small vessel disease and intracranial bleeding risk: Prognostic and practical significance

Balancing the risks of recurrent ischemia and antithrombotic-associated bleeding, particularly intracranial hemorrhage (ICH), is a key challenge in the secondary prevention of ischemic stroke and transient ischemic attack. In hyperacute ischemic stroke, the use of acute reperfusion therapies is determined by the balance of anticipated benefit and the risk of ICH. Cerebral small vessel disease (CSVD) causes most spontaneous ICH. Here, we review the evidence linking neuroimaging markers of CSVD to antithrombotic and thrombolytic-associated ICH, with emphasis on cerebral microbleeds (CMB). We discuss their role in the prediction of ICH, and practical implications for clinical decision making. Although current observational data suggest CMB presence should not preclude antithrombotic therapy in patients with ischemic stroke or TIA, they are useful for improving ICH risk prediction with potential relevance for determining the optimal secondary prevention strategy, including the use of left atrial appendage occlusion. Following ICH, recommencing antiplatelets is probably safe in most patients, while the inconclusive results of recent randomized controlled trials of anticoagulant use makes recruitment to ongoing trials (including those testing left atrial appendage occlusion) in this area a high priority. Concern regarding CSVD and ICH risk after hyperacute stroke treatment appears to be unjustified in most patients, though some uncertainty remains regarding patients with very high CMB burden and other risk factors for ICH. We encourage careful phenotyping for underlying CSVD in future trials, with the potential to enhance precision medicine in stroke.

Brain Enlarged Perivascular Spaces as Imaging Biomarkers of Cerebrovascular Disease: A Clinical Narrative Review

Perivascular spaces or Virchow-Robin spaces form pathways along the subarachnoid spaces that facilitate the effective clearance of brain metabolic by-products through intracellular exchange and drainage of cerebrospinal fluid. Best seen on magnetic resonance imaging of the brain, enlarged perivascular spaces (EPVSs) are increasingly recognized as potential imaging biomarkers of neurological conditions. EPVSs are an established subtype of cerebral small-vessel disease; however, their associations with other cerebrovascular disorders are yet to be fully understood. In particular, there has been great interest in the association between the various parameters of EPVSs, such as number, size, and topography, and vascular neurological conditions. Studies have identified cross-sectional and longitudinal relationships between EPVS parameters and vascular events, such as ischemic stroke (both clinical and silent), intracerebral hemorrhage, vascular risk factors, such as age and hypertension, and neurodegenerative processes, such as vascular dementia and Alzheimer disease. However, these studies are limited by heterogeneity of data and the lack of consistent results across studied populations. Existing meta-analyses also fail to provide uniformity of results. We performed a qualitative narrative review with an aim to provide an overview of the associations between EPVSs and cerebrovascular diseases, which may help recognize gaps in our knowledge, inform the design of future studies, and advance the role of EPVSs as imaging biomarkers.

Global Cortical Atrophy Is Associated with an Unfavorable Outcome in Stroke Patients on Oral Anticoagulation

INTRODUCTION

Measures of cerebral small vessel disease (cSVD), such as white matter hyperintensities (WMH) and cerebral microbleeds (CMB), are associated with an unfavorable clinical course in stroke patients on oral anticoagulation (OAC) for atrial fibrillation (AF). Here, we investigated whether similar findings can be observed for global cortical atrophy (GCA).

METHODS

Registry-based prospective observational study of 320 patients treated with OAC following AF stroke. Patients underwent magnetic resonance imaging (MRI) allowing assessment of GCA. Using the simplified visual Pasquier scale, the severity of GCA was categorized as follows: 0: no atrophy, 1: mild atrophy; 2: moderate atrophy, and 3: severe atrophy. Using adjusted logistic and Cox regression analysis, we investigated the association of GCA using a composite outcome measure, comprising: (i) recurrent acute ischemic stroke (IS); (ii) intracranial hemorrhage (ICH); and (iii) death.

RESULTS

In our time to event analysis after adjusting for potential confounders (i.e., WMH, CMB, age, sex, diabetes, arterial hypertension, coronary heart disease, hyperlipidemia, and antiplatelet use), GCA was associated with an increased risk for the composite outcome in all three degrees of atrophy (grade 1: aHR 3.95, 95% CI 1.34-11.63, p = 0.013; grade 2: aHR 3.89, 95% CI 1.23-12.30, p = 0.021; grade 3: aHR 4.16, 95% CI 1.17-14.84, p = 0.028).

CONCLUSION

GCA was associated with our composite outcome also after adjusting for other cSVD markers (i.e., CMB, WMH) and age, indicating that GCA may potentially serve as a prognostic marker for stroke patients with atrial fibrillation on oral anticoagulation.

Clinical and neuroimaging risk factors associated with the development of intracerebral hemorrhage while taking direct oral anticoagulants

BACKGROUND AND AIMS

Intracerebral hemorrhage (ICH) associated with direct oral anticoagulant (DOAC) usage confers significant mortality/disability. We aimed to understand the clinical and neuroimaging features associated with developing ICH among DOAC users.

METHODS

Clinical and radiological data were collected from consecutive DOAC users with ICH (DOAC-ICH) and age-matched controls without ICH from a single referral center. The frequency/distribution of MRI markers of hemorrhage risk were assessed. Baseline demographics and neuroimaging markers were compared in univariate tests. Significant associations (p < 0.1) were entered into a multivariable regression model to determine predictors of ICH.

RESULTS

86 DOAC-ICH and 94 ICH-free patients were included. Diabetes, coronary artery disease, prior ischemic stroke, smoking history, and antiplatelet usage were more common in ICH patients than ICH-free DOAC users. In the neuroimaging analyses, severe white matter hyperintensities (WMHs), lacunes, cortical superficial siderosis (cSS), and cerebral microbleeds (CMBs) were more common in the ICH cohort than the ICH-free cohort. In the multivariable regression, diabetes [OR 3.53 95% CI (1.05-11.87)], prior ischemic stroke [OR 14.80 95% CI (3.33-65.77)], smoking history [OR 3.08 95% CI (1.05-9.01)], CMBs [OR 4.07 95% CI (1.45-11.39)], and cSS [OR 39.73 95% CI (3.43-460.24)] were independently associated with ICH.

CONCLUSIONS

Risk factors including diabetes, prior stroke, and smoking history as well as MRI biomarkers including CMBs and cSS are associated with ICH in DOAC users. Although screening MRIs are not typically performed prior to initiating DOAC therapy, these data suggest that patients of high-hemorrhagic risk may be identified.

Cerebral Small Vessel Diseases and Outcomes for Acute Ischemic Stroke Patients after Endovascular Therapy

The correlation between cerebral small vessel disease (CSVD) and the outcomes of acute ischemic stroke (AIS) patients after endovascular therapy (EVT) remains elusive. We aimed to investigate the effect of combined white matter hyperintensities (WMH) and enlarged perivascular spaces (EPVS) as detected in magnetic resonance imaging (MRI) at baseline on clinical outcomes in patients with AIS who underwent EVT. AIS patients that experienced EVT were retrospectively analyzed in this single-center study. Using MRIs taken prior to EVT, we rated WMH and EPVS as the burden of CSVD and dichotomized the population into two groups: absent-to-moderate and severe. Neurological outcome was assessed at day 90 with a modified Rankin Scale (mRS). Symptomatic intracerebral hemorrhage (sICH), early neurological deterioration (END), malignant cerebral edema (MCE), and hospital death were secondary outcomes. Of the 100 patients (64.0% male; mean age 63.71 ± 11.79 years), periventricular WMHs (28%), deep WMHs (41%), EPVS in basal ganglia (53%), and EPVS in centrum semiovale (73%) were observed. In addition, 69% had an absent-to-moderate total CSVD burden and 31.0% had a severe burden. The severe CSVD was not substantially linked to either the primary or secondary outcomes. Patients with AIS who underwent EVT had an elevated risk (OR: 7.89, 95% CI: 1.0, 62.53) of END if they also had EPVS. When considering WMH and EPVS together as a CSVD burden, there seemed to be no correlation between severe CSVD burden and sICH, END, or MCE following EVT for AIS patients. Further studies are warranted to clarify the relationship between CSVD burden and the occurrence, progression, and prognosis of AIS.

Prevalence and Risk Factors for Enlarged Perivascular Spaces in Young Adults from a Neurology Clinic-Based Cohort

(1) Background: This study aimed to investigate the prevalence and risk factors for enlarged perivascular spaces (EPVS) in young adults from a neurology clinic-based cohort (≤45 years old) via unenhanced brain MRI. (2) Methods: A total of 931 young adults from a neurology clinic-based cohort who underwent unenhanced brain MRI between 1 January 2021 and 30 June 2021 were retrospectively included in this study. The EPVS were rated in the centrum semiovale (CSO-EPVS), basal ganglia (BG-EPVS), and midbrain (MB-EPVS) using a visual rating scale. The degrees of the CSO-EPVS, BG-EPVS, and MB-EPVS were all divided by a cutoff value of 1. Demographic factors, vascular risk factors, and symptoms were analyzed using the chi-square test and logistic regression to determine the risk factors of EPVS. (3) Results: The overall prevalence of EPVS was 99.8% (929/931). The CSO-EPVS, BG-EPVS, and MB-EPVS were predominantly scored as 1 (52.1%, 79.1%, and 58.3%, respectively). Logistic regression analysis identified age and hypertension as factors affecting the degrees of CSO-EPVS and BG-EPVS (p < 0.05). Hypertension (p < 0.001) and diabetes (p = 0.014) were revealed to be factors affecting the degree of BG-EPVS. Furthermore, patients with headache (OR = 1.807; p = 0.001) and dizziness (OR = 1.574; p = 0.025) were associated with MB-EPVS. (4) Conclusions: EPVS were frequently found in young adults and could be related to the symptoms. Age, hypertension, and diabetes were the risk factors for the severity of EPVS in the corresponding brain regions.

Clinical neuroimaging in intracerebral haemorrhage related to cerebral small vessel disease: contemporary practice and emerging concepts

INTRODUCTION

About 80% of all non-traumatic intracerebral haemorrhage (ICH) are caused by the sporadic cerebral small vessel diseases deep perforator arteriopathy (DPA, also termed hypertensive arteriopathy or arteriolosclerosis) and cerebral amyloid angiopathy (CAA), though these frequently co-exist in older people. Contemporary neuroimaging (MRI and CT) detects an increasing spectrum of haemorrhagic and non-haemorrhagic imaging biomarkers of small vessel disease which may identify the underlying arteriopathies.

AREAS COVERED

We discuss biomarkers for cerebral small vessel disease subtypes in ICH, and explore their implications for clinical practice and research.

EXPERT OPINION

ICH is not a single disease, but results from a defined range of vascular pathologies with important implications for prognosis and treatment. The terms "primary" and "hypertensive" ICH are poorly defined and should be avoided, as they encourage incomplete investigation and classification. Imaging-based criteria for CAA will show improved diagnostic accuracy, but specific imaging biomarkers of DPA are needed. Ultra-high-field 7T-MRI using structural and quantitative MRI may provide further insights into mechanisms and pathophysiology of small vessel disease. We expect neuroimaging biomarkers and classifications to allow personalized treatments (e.g. antithrombotic drugs) in clinical practice and to improve patient selection and monitoring in trials of targeted therapies directed at the underlying arteriopathies.

Post-mortem correlates of Virchow-Robin spaces detected on in vivo MRI

The purpose of our study is to quantify the extent to which Virchow-Robin spaces (VRS) detected on in vivo MRI are reproducible by post-mortem MRI.Double Echo Steady State 3T MRIs were acquired post-mortem in 49 double- and 32 single-hemispheric formalin-fixed brain sections from 12 patients, who underwent conventional diagnostic 1.5 or 3T MRI in median 22 days prior to death (25% to 75%: 12 to 134 days). The overlap of in vivo and post-mortem VRS segmentations was determined accounting for potential confounding factors.The reproducibility of VRS found on in vivo MRI by post-mortem MRI, in the supratentorial white matter was in median 80% (25% to 75%: 60 to 100). A lower reproducibility was present in the basal ganglia, with a median of 47% (25% to 75%: 30 to 50).VRS segmentations were histologically confirmed in one double hemispheric section.Overall, the majority of VRS found on in vivo MRI was stable throughout death and formalin fixation, emphasizing the translational potential of post-mortem VRS studies.

New Insights Into Cerebrovascular Pathophysiology and Hypertension

Despite advances in acute management and prevention of cerebrovascular disease, stroke and vascular cognitive impairment together remain the world's leading cause of death and neurological disability. Hypertension and its consequences are associated with over 50% of ischemic and 70% of hemorrhagic strokes but despite good control of blood pressure (BP), there remains a 10% risk of recurrent cerebrovascular events, and there is no proven strategy to prevent vascular cognitive impairment. Hypertension evolves over the lifespan, from predominant sympathetically driven hypertension with elevated mean BP in early and mid-life to a late-life phenotype of increasing systolic and falling diastolic pressures, associated with increased arterial stiffness and aortic pulsatility. This pattern may partially explain both the increasing incidence of stroke in younger adults as well as late-onset, chronic cerebrovascular injury associated with concurrent systolic hypertension and historic mid-life diastolic hypertension. With increasing arterial stiffness and autonomic dysfunction, BP variability increases, independently predicting the risk of ischemic and intracerebral hemorrhage, and is potentially modifiable beyond control of mean BP. However, the interaction between hypertension and control of cerebral blood flow remains poorly understood. Cerebral small vessel disease is associated with increased pulsatility in large cerebral vessels and reduced reactivity to carbon dioxide, both of which are being targeted in early phase clinical trials. Cerebral arterial pulsatility is mainly dependent upon increased transmission of aortic pulsatility via stiff vessels to the brain, while cerebrovascular reactivity reflects endothelial dysfunction. In contrast, although cerebral autoregulation is critical to adapt cerebral tone to BP fluctuations to maintain cerebral blood flow, its role as a modifiable risk factor for cerebrovascular disease is uncertain. New insights into hypertension-associated cerebrovascular pathophysiology may provide key targets to prevent chronic cerebrovascular disease, acute events, and vascular cognitive impairment.

Research progress in atrial fibrillation with cerebral small vessel disease

Non-valvular atrial fibrillation is a common arrhythmia and a major risk factor for cardioembolic stroke. Small cerebral vascular disease is a syndrome of clinical, cognitive, imaging, and pathological manifestations caused by intracranial small vascular lesions. The imaging findings on cranial magnetic resonance usually shows recent subcortical small infarction, vascularised lacunae, white matter hypersignal, perivascular space enlargement, cerebral microhemorrhage, and brain atrophy. It is a major cause of neurological loss and cognitive function decline in the elderly. Current studies suggest that atrial fibrillation may increase the imaging load of cerebral small vessel disease through a series of mechanisms such as microembolization, hypoperfusion, inflammation, endothelial dysfunction, and lymphoid system dysfunction. The imaging of cerebral small vessel disease with atrial fibrillation has a potential relationship with cognitive function decline and is related to the occurrence and prognosis of stroke, even more has a potential role in suggesting the etiology and secondary prevention strategies of ischemic stroke.

Anticoagulation after stroke: persistent uncertainties

PURPOSE OF REVIEW

Direct oral anticoagulants (DOAC) are the mainstay of anticoagulant therapy for stroke prevention in patients with nonvalvular atrial fibrillation. Persistent uncertainties remain in different areas, and this review discusses current dilemmas based on selected studies.

RECENT FINDINGS

Optimal timing of DOAC initiation after a recent ischaemic stroke in patients with atrial fibrillation is currently unknown and subject of ongoing randomized controlled trials. Ischaemic stroke despite anticoagulant therapy in patients with atrial fibrillation is frequent, constitutes heterogeneous causes (competing stroke cause, medication error and cardioembolism despite anticoagulation) and optimal treatment is currently unknown. Thorough etiological work-up is justified. Recent randomized controlled trials found no beneficial effect of DOAC therapy in unselected patients with embolic stroke of undetermined source (ESUS). Currently ongoing trials targeting subgroup of ESUS patients with additional atrial cardiopathy will provide novel data. Cerebral mircobleeds combined in a novel risk score (MICON score) provide good predictive value to stratify the risk of intracranial haemorrhage in patients taking anticoagulants. Use of DOAC after intracerebral haemorrhage in patients with atrial fibrillation is subject of ongoing trials.

SUMMARY

There are still significant uncertainties in anticoagulant management in patients with stroke. Ongoing trials will soon provide novel data to improve management of these patients.

Enlarged perivascular spaces and hemorrhagic transformation after acute ischemic stroke

Background

Enlarged perivascular spaces (EPVS) are considered to be neuroimaging markers of cerebral small vessel disease (CSVD). It remains unknown whether EPVS are associated with hemorrhagic transformation (HT) after acute ischemic stroke (AIS). We performed this retrospective cohort study to explore the associations of EPVS with clinical risk factors and other CSVD imaging features, and to investigate the relationship between EPVS and HT in patients with AIS.

Methods

AIS patients admitted within 24 hours of stroke onset between January 2016 and December 2017 were consecutively enrolled. EPVS, lacunes, and white matter hyperintensities (WMH) were rated with validated rating scales on magnetic resonance images after the stroke. HT was defined as hemorrhage determined by follow-up brain imaging during the patients' hospital stay. Logistic regression was used to determine the risk factors and associations with other CSVD markers of EPVS in the basal ganglia (BG) and centrum semiovale (CS) regions, and the impact of EPVS on HT was further explored.

Results

Among 494 included patients (mean age 66.4 years, 58.1% male), 81 (16.4%) experienced HT. In the multivariate logistic analyses, increasing age [odd ratio (OR) 1.041, 95% confidence interval (CI), 1.017-1.066], hypertension (OR 2.174, 95% CI, 1.338-3.532), lacunar stroke (OR 1.968, 95% CI, 1.169-3.314), CS-EPVS (OR 2.474, 95% CI, 1.796-3.407), and periventricular WMH (OR 2.140, 95% CI, 1.441-3.176) were significantly associated with BG-EPVS; whereas only BG-EPVS (OR 4.349, 95% CI, 2.281-8.291) were independently related to CS-EPVS. After adjustment for potential variables, neither BG-EPVS (OR 0.674, 95% CI, 0.336-1.350) nor CS-EPVS (OR 0.792, 95% CI, 0.334-1.879) was significantly associated with the occurrence of HT.

Conclusions

Our data showed that EPVS in the BG and CS regions were interrelated and had different risk factors in ischemic stroke patients. EPVS (particularly that in BG) were independently related to other CSVD markers. The presence or burden of EPVS was not significantly associated with HT after AIS.

The Glymphatic System: A Novel Therapeutic Target for Stroke Treatment

The glymphatic system (GS) is a novel defined brain-wide perivascular transit network between cerebrospinal fluid (CSF) and interstitial solutes that facilitates the clearance of brain metabolic wastes. The complicated network of the GS consists of the periarterial CSF influx pathway, astrocytes-mediated convective transport of fluid and solutes supported by AQP4 water channels, and perivenous efflux pathway. Recent researches indicate that the GS dysfunction is associated with various neurological disorders, including traumatic brain injury, hydrocephalus, epilepsy, migraine, and Alzheimer’s disease (AD). Meanwhile, the GS also plays a pivotal role in the pathophysiological process of stroke, including brain edema, blood–brain barrier (BBB) disruption, immune cell infiltration, neuroinflammation, and neuronal apoptosis. In this review, we illustrated the key anatomical structures of the GS, the relationship between the GS and the meningeal lymphatic system, the interaction between the GS and the BBB, and the crosstalk between astrocytes and other GS cellular components. In addition, we contributed to the current knowledge about the role of the GS in the pathology of stroke and the role of AQP4 in stroke. We further discussed the potential use of the GS in early risk assessment, diagnostics, prognostics, and therapeutics of stroke.