Cerebral computed tomography-graded white matter lesions are associated with worse outcome after thrombolysis in patients with stroke

Leukoaraiosis in patients with tirofiban before endovascular thrombectomy: A post hoc analysis of a multicentre randomized clinical trial

BACKGROUND AND PURPOSE

To evaluate the effectiveness and safety of intravenous tirofiban before endovascular thrombectomy in subgroups of acute ischemic stroke patients with different degrees of leukoaraiosis (LA).

METHODS

Patients of the RESCUE BT trial whose LA grade could be assessed were included. Eligible patients were dichotomized into two strata according to the van Swieten scale (VSS) score, absent-to-moderate LA (VSS score <3) and severe LA (VSS score ≥3). Furthermore, patients were divided into tirofiban and placebo groups in each stratum. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Safety outcome was radiological intracranial hemorrhage within 48 h.

RESULTS

861 patients were included, 439 patients with absent-to-moderate LA and 422 patients with severe LA. There were no significant differences in 90-day mRS score between the tirofiban and placebo groups in either stratum (absent-to-moderate LA: adjusted OR 0.92 (95%CI, 0.66-1.28), P = 0.62; severe LA: adjusted OR 0.99 (95% CI, 0.69-1.42), P = 0.96). In the severe LA stratum, the occurrence of radiologic intracranial hemorrhage was greater in the tirofiban group compared to the placebo group. (35.7% vs 26.4%; adjusted OR, 1.72 (95% CI, 1.12-2.66); P = 0.014). However, no difference was observed in the absent-to-moderate LA stratum (33.2% vs 29.3%; adjusted OR, 1.15 (95% CI, 0.76-1.75); P = 0.51).

CONCLUSION

There was no significant difference in disability severity at 90 days when treating AIS patients using intravenous tirofiban before endovascular therapy, in either absent-to-moderate or severe LA strata. It should be noted that intravenous tirofiban before endovascular therapy increases the incidence of radiologic intracranial hemorrhage in patients with severe LA.

Casein Kinase 2 Signaling in White Matter Stroke

The growth of the aging population, together with improved stroke care, has resulted in an increase in stroke survivors and a rise in recurrent events. Axonal injury and white matter (WM) dysfunction are responsible for much of the disability observed after stroke. The mechanisms of WM injury are distinct compared to gray matter and change with age. Therefore, an ideal stroke therapeutic must restore neuronal and axonal function when applied before or after a stroke, and it must also protect across age groups. Casein kinase 2 (CK2), is expressed in the brain, including WM, and is regulated during the development and numerous disease conditions such as cancer and ischemia. CK2 activation in WM mediates ischemic injury by activating the Cdk5 and AKT/GSK3β signaling pathways. Consequently, CK2 inhibition using the small molecule inhibitor CX-4945 (Silmitasertib) correlates with preservation of oligodendrocytes, conservation of axon structure, and axonal mitochondria, leading to improved functional recovery. Remarkably, CK2 inhibition promotes WM function when applied after ischemic injury by specifically regulating the AKT/GSK3β pathways. The blockade of the active conformation of AKT confers post-ischemic protection to young and old WM by preserving mitochondria, implying AKT as a common therapeutic target across age groups. Using a NanoString nCounter miRNA expression profiling, comparative analyses of ischemic WM with or without CX-4945 treatment reveal that miRNAs are expressed at high levels in WM after ischemia, and CX-4945 differentially regulates some of these miRNAs. Therefore, we propose that miRNA regulation may be one of the protective actions of CX-4945 against WM ischemic injury. Silmitasertib is FDA approved and currently in use for cancer and Covid patients; therefore, it is plausible to repurpose CK2 inhibitors for stroke patients.

The Impact of Ischemic Stroke on Gray and White Matter Injury Correlated With Motor and Cognitive Impairments in Permanent MCAO Rats: A Multimodal MRI-Based Study

Background

Identifying the alterations of the cerebral gray and white matter is an important prerequisite for developing potential pharmacological therapy for stroke. This study aimed to assess the changes of gray and white matter after permanent middle cerebral artery occlusion (pMCAO) in rats using magnetic resonance imaging (MRI), and to correlate them with the behavior performance.

Methods

Rats were subjected to pMCAO or sham surgery and reared for 30 days. Motor and cognitive function of the rats were examined by gait and Morris water maze (MWM) tests, respectively. Multimodal MRI was conducted to examine the functional and structural changes of the gray and white matter followed with luxol fast blue (LFB) staining.

Results

The gait and MWM tests revealed significant motor and cognitive dysfunction in pMCAO rats, respectively. Magnetic resonance angiography presented abnormal intracranial arteries in pMCAO rats with reduced signal intensity of the anterior cerebral artery, anterior communicating cerebral artery, internal carotid artery, and increased basilar artery vessel signal compared with sham rats. Arterial spin labeling confirmed the decreased cerebral blood flow in the infarcted sensorimotor cortex and striatum. Structural T2-weighted imaging and T2 mapping showed brain atrophy and elevation of T2 value in the gray (sensorimotor cortex, striatum) and white (external capsule, internal capsule) matter of pMCAO rats. The results from diffusion tensor imaging (DTI) corresponded well with LFB staining showing reduced relative FA accompanied with increased relative AD and RD in the gray and white matter of pMCAO rats compared with sham rats. Fiber tracking derived from DTI further observed significantly reduced fiber density and length in the corresponding brain regions of pMCAO rats compared with sham rats. Specially, the DTI parameters (especially FA) in the relevant gray matter and white matter significantly correlated with the behavior performance in the gait and MWM tests.

Conclusion

Collectively, the gray and white matter damages could be non-invasively monitored in pMCAO rats by multimodal MRI. DTI-derived parameters, particularly the FA, might be a good imaging index to stage gray and white matter damages associated with post-stroke motor and cognitive impairments.

Leukoaraiosis severity and post-reperfusion outcomes in acute ischaemic stroke: A meta-analysis

OBJECTIVES

Severity of leukoaraiosis may mediate outcomes after reperfusion therapy in acute ischaemic stroke (AIS) patients. However, the level of the association remains poorly understood. We performed a meta-analysis to investigate the impact of leukoaraiosis severity on functional outcome, survival, haemorrhagic complications, and procedural success in AIS patients treated with intravenous thrombolysis and/or endovascular thrombectomy.

MATERIALS AND METHODS

PubMed, EMBASE and the Cochrane library were searched for studies on leukoaraiosis in AIS receiving reperfusion therapy. A random-effects meta-analysis was conducted for post-reperfusion outcomes in AIS patients with absent-to-mild leukoaraiosis and moderate-to-severe leukoaraiosis. The strength of association between moderate-to-severe leukoaraiosis and poor outcomes was quantified using odds ratios (OR).

RESULTS

A total of 15 eligible studies involving 6460 patients (1451 with moderate-to-severe leukoaraiosis and 5009 with absent-to-mild leukoaraiosis) were included in the meta-analysis. Moderate-to-severe leukoaraiosis was significantly associated with poor 90-day functional outcome (OR 3.16; 95% confidence interval (CI) 2.69-3.72; p < .0001), 90-day mortality (OR 3.11; 95% CI 2.27-4.26; p < .0001) and increased risk of symptomatic intracerebral haemorrhage (OR 1.69; 95% CI 1.24-2.32; p = .001) after reperfusion therapy. Overall, no significant association of leukoaraiosis severity with haemorrhagic transformation (HT) and angiographic recanalization status were observed. However, subgroup analysis revealed a significant association of WML severity with HT in patients receiving EVT.

CONCLUSION

Leukoaraiosis is a useful prognostic biomarker in AIS. Patients with moderate-to-severe leukoaraiosis on baseline imaging are likely to have worse clinical and safety outcomes after reperfusion therapy.

Emerging role of white matter lesions in cerebrovascular disease

White matter lesions have been implicated in the setting of stroke, dementia, intracerebral haemorrhage, several other cerebrovascular conditions, migraine, various neuroimmunological diseases like multiple sclerosis, disorders of metabolism, mitochondrial diseases and others. While much is understood vis a vis neuroimmunological conditions, our knowledge of the pathophysiology of these lesions, and their role in, and implications to, management of cerebrovascular diseases or stroke, especially in the elderly, are limited. Several clinical assessment tools are available for delineating white matter lesions in clinical practice. However, their incorporation into clinical decision-making and specifically prognosis and management of patients is suboptimal for use in standards of care. This article sought to provide an overview of the current knowledge and recent advances on pathophysiology, as well as clinical and radiological assessment, of white matter lesions with a focus on its development, progression and clinical implications in cerebrovascular diseases. Key indications for clinical practice and recommendations on future areas of research are also discussed. Finally, a conceptual proposal on putative mechanisms underlying pathogenesis of white matter lesions in cerebrovascular disease has been presented. Understanding of pathophysiology of white matter lesions and how they mediate outcomes is important to develop therapeutic strategies.

Neuroimaging Markers of Cerebral Small Vessel Disease on Hemorrhagic Transformation and Functional Outcome After Intravenous Thrombolysis in Patients With Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Objective: The aim of this study was to perform a systematic review and meta-analysis to assess whether cerebral small vessel disease (CSVD) on neuroimaging of patients with acute ischemic stroke (AIS) treated with intravenous thrombolysis (IVT) is associated with an increased risk of hemorrhagic transformation (HT), symptomatic intracranial hemorrhage (sICH), and poor functional outcome (PFO). Methods: A thorough search of several databases was carried out to identify relevant studies up to December 2020. We included studies of patients with AIS and neuroimaging markers of CSVD treated with IVT. The primary outcome was HT, and the secondary outcomes were sICH and 3-month PFO. The quality of the studies involved was evaluated using the Newcastle-Ottawa Scale (NOS). The meta-analysis with the fixed effects model was performed. Results: Twenty-four eligible studies (n = 9,419) were pooled in the meta-analysis. All included studies were regarded as high quality with the NOS scores of at least 6 points. The meta-analysis revealed associations between the presence of CSVD and HT, sICH, and the 3-month PFO after IVT. Compared with no CSVD, the presence of CSVD was associated with an increased risk of HT (OR: 1.81, 95% CI: 1.52-2.16), sICH (OR: 2.42, 95% CI: 1.76-3.33), and 3-month PFO (OR: 2.15, 95% CI: 1.89-2.44). For patients with AIS complicated with CSVD, compared with a CSVD score of 0-1, a CSVD score of 2-4 was associated with an increased risk of HT (OR: 3.10, 95% CI: 1.67-5.77), sICH (OR: 2.86, 95% CI: 1.26-6.49), and 3-month PFO (OR: 4.58, 95% CI: 2.97-7.06). Conclusion: Patients with AIS complicated with neuroimaging markers of CSVD are at increased risk of HT and 3-month PFO after IVT. However, it is still necessary to clarify the exact role of CSVD in the occurrence, development, and prognosis of AIS. Systematic Review Registration: www.ClinicalTrials.gov, identifier CRD4202123 3900.

White matter hyperintensity volume in pre-diabetes, diabetes and normoglycemia

INTRODUCTION

As white matter hyperintensities (WMHs) of the brain are associated with an increased risk of stroke, cognitive decline, and depression, elucidating the associated risk factors is important. In addition to age and hypertension, pre-diabetes and diabetes may play important roles in the development of WMHs. Previous studies have, however, shown conflicting results. We aimed to investigate the effect of diabetes status and quantitative markers of glucose metabolism on WMH volume in a population-based cohort without prior cardiovascular disease.

RESEARCH DESIGN AND METHODS

400 participants underwent 3 T MRI. WMHs were manually segmented on 3D fluid-attenuated inversion recovery images. An oral glucose tolerance test (OGTT) was administered to all participants not previously diagnosed with diabetes to assess 2-hour serum glucose concentrations. Fasting glucose concentrations and glycated hemoglobin (HbA1c) levels were measured. Zero-inflated negative binomial regression analyses of WMH volume and measures of glycemic status were performed while controlling for cardiovascular risk factors and multiple testing.

RESULTS

The final study population comprised 388 participants (57% male; age 56.3±9.2 years; n=98 with pre-diabetes, n=51 with diabetes). Higher WMH volume was associated with pre-diabetes (p=0.001) and diabetes (p=0.026) compared with normoglycemic control participants after adjustment for cardiovascular risk factors. 2-hour serum glucose (p<0.001), but not fasting glucose (p=0.389) or HbA1c (p=0.050), showed a significant positive association with WMH volume after adjustment for cardiovascular risk factors.

CONCLUSION

Our results indicate that high 2-hour serum glucose concentration in OGTT, but not fasting glucose levels, may be an independent risk factor for the development of WMHs, with the potential to inform intensified prevention strategies in individuals at risk of WMH-associated morbidity.

Associated factors of white matter hyperintensity volume: a machine-learning approach

To identify the most important parameters associated with cerebral white matter hyperintensities (WMH), in consideration of potential collinearity, we used a data-driven machine-learning approach. We analysed two independent cohorts (KORA and SHIP). WMH volumes were derived from cMRI-images (FLAIR). 90 (KORA) and 34 (SHIP) potential determinants of WMH including measures of diabetes, blood-pressure, medication-intake, sociodemographics, life-style factors, somatic/depressive-symptoms and sleep were collected. Elastic net regression was used to identify relevant predictor covariates associated with WMH volume. The ten most frequently selected variables in KORA were subsequently examined for robustness in SHIP. The final KORA sample consisted of 370 participants (58% male; age 55.7 ± 9.1 years), the SHIP sample comprised 854 participants (38% male; age 53.9 ± 9.3 years). The most often selected and highly replicable parameters associated with WMH volume were in descending order age, hypertension, components of the social environment (i.e. widowed, living alone) and prediabetes. A systematic machine-learning based analysis of two independent, population-based cohorts showed, that besides age and hypertension, prediabetes and components of the social environment might play important roles in the development of WMH. Our results enable personal risk assessment for the development of WMH and inform prevention strategies tailored to the individual patient.

Evaluating severity of white matter lesions from computed tomography images with convolutional neural network

PURPOSE

Severity of white matter lesion (WML) is typically evaluated on magnetic resonance images (MRI), yet the more accessible, faster, and less expensive method is computed tomography (CT). Our objective was to study whether WML can be automatically segmented from CT images using a convolutional neural network (CNN). The second aim was to compare CT segmentation with MRI segmentation.

METHODS

The brain images from the Helsinki University Hospital clinical image archive were systematically screened to make CT-MRI image pairs. Selection criteria for the study were that both CT and MRI images were acquired within 6 weeks. In total, 147 image pairs were included. We used CNN to segment WML from CT images. Training and testing of CNN for CT was performed using 10-fold cross-validation, and the segmentation results were compared with the corresponding segmentations from MRI.

RESULTS

A Pearson correlation of 0.94 was obtained between the automatic WML volumes of MRI and CT segmentations. The average Dice similarity index validating the overlap between CT and FLAIR segmentations was 0.68 for the Fazekas 3 group.

CONCLUSION

CNN-based segmentation of CT images may provide a means to evaluate the severity of WML and establish a link between CT WML patterns and the current standard MRI-based visual rating scale.

The relationship of leukoaraiosis, haemorrhagic transformation and prognosis at 3 months after intravenous thrombolysis in elderly patients aged ≥ 60 years with acute cerebral infarction

Backgroud

As the elderly stroke population continues to increase, we will have to confront greater challenges regarding how to choose suitable patients to reduce thrombolysis-related bleeding events and accurately judge their prognosis. Therefore, we evaluated the relationship among leukoaraiosis (LA), haemorrhagic transformation (HT) and the prognosis at 3 months after intravenous (IV) thrombolysis in elderly patients aged ≥ 60 years with acute cerebral infarction (ACI).

Methods

We prospectively and consecutively chose 125 elderly patients aged ≥ 60 years with ACI who could accept and be suitable for IV recombinant tissue plasminogen activator (rtPA) after excluding 6 cases. Brain computed tomography(CT) was used to assess LA by using the modified Van Swieten scale (mVSS) before treatment and the modified Rankin scale (mRS) to appraise prognosis at 3 months after IV rtPA. Binary logistic regression was used to analyse the predictors of HT and the prognosis of ACI.

Results

Our data indicated that by brain CT, 26.4% of all patients showed severe LA, and the rate of HT and symptomatic intracranial haemorrhage (sICH) were 12.0% and 9.6%, respectively. Severe LA was evidently associated with HT (odds ratio [OR] 3.272, 95% confidence interval [CI] 1.010–10.598, P = 0.048) rather sICH (P > 0.05). Moreover, we also found that severe LA was associated with poor functional prognosis (OR 5.266, 95% CI 1.592–17.419, P = 0.006).

Conclusion

Our results showed that LA was associated with HT and adverse clinical prognosis rather sICH after IV rtPA in elderly patients aged ≥60 years with ACI. Although LA may increase the risk of bleeding but not fatal haemorrhage after IV thrombolysis, therefore, we should actively select an appropriate elderly population for thrombolytic treatment and have reasonable judgments on the outcomes.

The association of white matter hyperintensities with stroke outcomes and antiplatelet therapy in minor stroke patients

Background

To characterize the severity and distribution of white matter hyperintensities (WMHs) and to assess the relationship of WMHs with initial stroke severity, 3-month functional outcome, stroke recurrence and response to antiplatelet therapies.

Methods

In Clopidogrel High-risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial, 787 minor stroke patients with baseline magnetic resonance imaging (MRI) information were included in this analysis. Deep and periventricular WMHs (DWMHs and PVWMHs) were rated using the Fazekas scale and categorized into mild (grades 0–2), moderate (grades 3–4) and severe (grades 5–6). Multivariable logistic regression was used to examine the associations between WMHs severities and outcomes, including initial stroke severity by the National Institutes of Health Stroke Scale (NIHSS) scores, 3-month functional outcome by modified Rankin Scale (mRS), and stroke recurrence. Cox proportional hazards model was used to assess the treatment-by-subgroup interaction effect.

Results

Among the 787 patients in this analysis, 432 (54.9%) had moderate or severe WMHs (3-6). Compared with mild WMHs, the adjusted odds ratio (OR) of severe WMHs for risk of higher NIHSS was 2.10, 95% confidence interval (CI), 1.26–3.48 (P=0.004). Both severities of SDWMHs (OR 1.66; 95% CI, 1.15–2.40; P=0.007) and PVWMHs (OR 1.47; 95% CI, 1.02–2.10; P=0.04) were associated with higher NIHSS scores. There were no statistically significant associations of WMHs with 3-month functional outcome and stroke recurrence. There were no significant interactions between WMHs and antiplatelet therapy.

Conclusions

In patients with minor stroke, both SDWMHs and PVWMHs might related with initial stroke severity. No interaction was detected between the severity of WMHs and antiplatelet treatment.

Heterogeneity of Astrocytes in Grey and White Matter

Astrocytes are a diverse and heterogeneous type of glial cells. The major task of grey and white matter areas in the brain are computation of information at neuronal synapses and propagation of action potentials along axons, respectively, resulting in diverse demands for astrocytes. Adapting their function to the requirements in the local environment, astrocytes differ in morphology, gene expression, metabolism, and many other properties. Here we review the differential properties of protoplasmic astrocytes of grey matter and fibrous astrocytes located in white matter in respect to glutamate and energy metabolism, to their function at the blood-brain interface and to coupling via gap junctions. Finally, we discuss how this astrocytic heterogeneity might contribute to the different susceptibility of grey and white matter to ischemic insults.

WMH and long-term outcomes in ischemic stroke

Objective

To investigate the relationship between baseline white matter hyperintensities (WMH) in patients with ischemic stroke and long-term risk of dementia, functional impairment, recurrent stroke, and mortality.

Methods

Following the Meta-analysis of Observational Studies in Epidemiology and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO protocol: CRD42018092857), we systematically searched Medline and Scopus for cohort studies of ischemic stroke patients examining whether MRI- or CT-assessed WMH at baseline are associated with dementia, functional impairment, recurrent stroke, and mortality at 3 months or later poststroke. We extracted data and evaluated study quality with the Newcastle–Ottawa scale. We pooled relative risks (RR) for the presence and severity of WMH using random-effects models.

Results

We included 104 studies with 71,298 ischemic stroke patients. Moderate/severe WMH at baseline were associated with increased risk of dementia (RR 2.17, 95% confidence interval [CI] 1.72–2.73), cognitive impairment (RR 2.29, 95% CI 1.48–3.54), functional impairment (RR 2.21, 95% CI 1.83–2.67), any recurrent stroke (RR 1.65, 95% CI 1.36–2.01), recurrent ischemic stroke (RR 1.90, 95% CI 1.26–2.88), all-cause mortality (RR 1.72, 95% CI 1.47–2.01), and cardiovascular mortality (RR 2.02, 95% CI 1.44–2.83). The associations followed dose-response patterns for WMH severity and were consistent for both MRI- and CT-defined WMH. The results remained stable in sensitivity analyses adjusting for age, stroke severity, and cardiovascular risk factors, in analyses of studies scoring high in quality, and in analyses adjusted for publication bias.

Conclusions

Presence and severity of WMH are associated with substantially increased risk of dementia, functional impairment, stroke recurrence, and mortality after ischemic stroke. WMH may aid clinical prognostication and the planning of future clinical trials.

Small Vessel Disease Is Associated with Tissue Inhibitor of Matrix Metalloproteinase-4 After Ischaemic Stroke

Small vessel disease (SVD) is frequent in aging and stroke patients. Inflammation and remodeling of extracellular matrix have been suggested as concurrent mechanisms of SVD. We investigated the relationship between imaging features of SVD and circulating metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in patients with ischaemic stroke. In patients treated with intravenous thrombolysis, we took blood samples before intravenous thrombolysis and 90 days after the acute stroke and analysed levels of MMPs and TIMPs. We assessed leukoaraiosis, number of lacunes and brain atrophy on pre-treatment CT scan and graded global SVD burden combining such features. We investigated associations between single features, global SVD and MMPs and TIMPs at baseline and at follow-up, retaining univariate statistically significant associations in multivariate linear regression analysis and adjusting for clinical confounders. A total of 255 patients [mean (±SD) = 68.6 (± 12.7) years, 154 (59%) males] were included, 107 (42%) had no signs of SVD; 47 (19%) had from moderate to severe SVD burden. A total of 107 (42%) patients had no signs of SVD; 47 (19%) had from moderate to severe SVD burden. After adjustment, only TIMP-4 proved associations with SVD features. Brain atrophy was associated with baseline TIMP-4 (β = 0.20;p = 0.019) and leukoaraiosis with 90 days TIMP-4 (β = 0.19; p = 0.013). Global SVD score was not associated with baseline TIMP-4 levels (β = 0.10; p = 0.072), whereas was associated with 90 days TIMP-4 levels (β = 0.21; p = 0.003). Total SVD burden was associated with higher TIMP-4 levels 90 days after stroke, whereas was not during the acute phase. Our results support a biological relationship between SVD grade and TIMP-4.

Cerebral White Matter Hyperintensities and Microbleeds in Acute Ischemic Stroke: Impact on Recanalization Therapies. A Review of the Literature

Cerebral white matter hyperintensities (WMH) and cerebral microbleeds (CMBs) are frequently seen on brain imaging acquired for acute ischemic stroke. Given the raising use of recanalization therapies - both intravenous and endovascular - the interest on the impact of WMH and CMBs on the risk of intracerebral hemorrhage and on functional outcome is growing. In this review, we will discuss the relevance of WMH and CMBs among patients with an acute ischemic stroke, focusing on the implications for recanalization therapies.

CK2 inhibition protects white matter from ischemic injury

Strokes occur predominantly in the elderly and white matter (WM) is injured in most strokes, contributing to the disability associated with clinical deficits. Casein kinase 2 (CK2) is expressed in neuronal cells and was reported to be neuroprotective during cerebral ischemia. Recently, we reported that CK2 is abundantly expressed by glial cells and myelin. However, in contrast to its role in cerebral (gray matter) ischemia, CK2 activation during ischemia mediated WM injury via the CDK5 and AKT/GSK3β signaling pathways (Bastian et al., 2018). Subsequently, CK2 inhibition using the small molecule inhibitor CX-4945 correlated with preservation of oligodendrocytes as well as conservation of axon structure and axonal mitochondria, leading to improved functional recovery. Notably, CK2 inhibition promoted WM function when applied before or after ischemic injury by differentially regulating the CDK5 and AKT/GSK3β pathways. Specifically, blockade of the active conformation of AKT conferred post-ischemic protection to young, aging, and old WM, suggesting a common therapeutic target across age groups. CK2 inhibitors are currently being used in clinical trials for cancer patients; therefore, it is important to consider the potential benefits of CK2 inhibitors during an ischemic attack.

Chronic kidney disease and poor outcomes in ischemic stroke: is impaired cerebral autoregulation the missing link?

BACKGROUND

Chronic kidney disease increases stroke incidence and severity but the mechanisms behind this cerebro-renal interaction are mostly unexplored. Since both vascular beds share similar features, microvascular dysfunction could be the possible missing link. Therefore, we examined the relationship between renal function and cerebral autoregulation in the early hours post ischemia and its impact on outcome.

METHODS

We enrolled 46 ischemic strokes (middle cerebral artery). Dynamic cerebral autoregulation was assessed by transfer function (coherence, phase and gain) of spontaneous blood pressure oscillations to blood flow velocity within 6 h from symptom-onset. Estimated glomerular filtration rate (eGFR) was calculated. Hemorrhagic transformation (HT) and white matter lesions (WML) were collected from computed tomography performed at presentation and 24 h. Outcome was evaluated with modified Rankin Scale at 3 months.

RESULTS

High gain (less effective autoregulation) was correlated with lower eGFR irrespective of infarct side (p < 0.05). Both lower eGFR and higher gain correlated with WML grade (p < 0.05). Lower eGFR and increased gain, alone and in combination, progressively reduced the odds of a good functional outcome [ipsilateral OR = 4.39 (CI95% 3.15-25.6), p = 0.019; contralateral OR = 8.15 (CI95% 4.15-15.6), p = 0.002] and increased risk of HT [ipsilateral OR = 3.48 (CI95% 0.60-24.0), p = 0.132; contralateral OR = 6.43 (CI95% 1.40-32.1), p = 0.034].

CONCLUSIONS

Lower renal function correlates with less effective dynamic cerebral autoregulation in acute ischemic stroke, both predicting a bad outcome. The evaluation of serum biomarkers of renal dysfunction could have interest in the future for assessing cerebral microvascular risk and relationship with stroke complications.

Quantitative Rapid Assessment of Leukoaraiosis in CT : Comparison to Gold Standard MRI

PURPOSE

The severity of white matter lesions (WML) is a risk factor of hemorrhage and predictor of clinical outcome after ischemic stroke; however, in contrast to magnetic resonance imaging (MRI) reliable quantification for this surrogate marker is limited for computed tomography (CT), the leading stroke imaging technique. We aimed to present and evaluate a CT-based automated rater-independent method for quantification of microangiopathic white matter changes.

METHODS

Patients with suspected minor stroke (National Institutes of Health Stroke scale, NIHSS < 4) were screened for the analysis of non-contrast computerized tomography (NCCT) at admission and compared to follow-up MRI. The MRI-based WML volume and visual Fazekas scores were assessed as the gold standard reference. We employed a recently published probabilistic brain segmentation algorithm for CT images to determine the tissue-specific density of WM space. All voxel-wise densities were quantified in WM space and weighted according to partial probabilistic WM content. The resulting mean weighted density of WM space in NCCT, the surrogate of WML, was correlated with reference to MRI-based WML parameters.

RESULTS

The process of CT-based tissue-specific segmentation was reliable in 79 cases with varying severity of microangiopathy. Voxel-wise weighted density within WM spaces showed a noticeable correlation (r = -0.65) with MRI-based WML volume. Particularly in patients with moderate or severe lesion load according to the visual Fazekas score the algorithm provided reliable prediction of MRI-based WML volume.

CONCLUSION

Automated observer-independent quantification of voxel-wise WM density in CT significantly correlates with microangiopathic WM disease in gold standard MRI. This rapid surrogate of white matter lesion load in CT may support objective WML assessment and therapeutic decision-making during acute stroke triage.

Recent Advances in Leukoaraiosis: White Matter Structural Integrity and Functional Outcomes after Acute Ischemic Stroke

Leukoaraiosis, a radiographic marker of cerebral small vessel disease detected on T2-weighted brain magnetic resonance imaging (MRI) as white matter hyperintensity (WMH), is a key contributor to the risk and severity of acute cerebral ischemia. Prior investigations have emphasized the pathophysiology of WMH development and progression; however, more recently, an association between WMH burden and functional outcomes after stroke has emerged. There is growing evidence that WMH represents macroscopic injury to the white matter and that the extent of WMH burden on MRI influences functional recovery in multiple domains following acute ischemic stroke (AIS). In this review, we discuss the current understanding of WMH pathogenesis and its impact on AIS and functional recovery.

Leukoaraiosis as an outcome predictor in the acute and subacute phases of stroke

INTRODUCTION

Leukoaraiosis (LA) is one of the neuroimaging features of cerebral small vessel disease and is associated with poor long-term prognosis. Areas covered: This narrative review focuses on the predictive role of LA on the evolution of the ischemic brain damage and on the clinical outcome in the subacute phase of stroke and in the short-term period afterwards. Expert commentary: LA predicts poorer tissue outcome and clinical prognosis also in acute and subacute stroke. In acute stroke, LA is associated with a less favorable fate of brain infarct and is a marker of increased risk of thrombolysis-related hemorrhagic transformation. The impaired cerebral microcirculation in LA patients may sustain the progression of ischemic lesion and enhance the bleeding risk. The short-term worse clinical outcome in ischemic stroke and intracranial hemorrhage patients with LA might be attributable to a state of altered brain connectivity. Endothelial failure, reduced micro-vessels density, and deficient collateral flow together with reduced functional reserve are some of the involved mechanisms. Future studies should aim at bridging the gap between the knowledge about LA pathophysiology and the therapeutic improvement of brain tissue perfusion and at producing data on early rehabilitation of stroke patients with LA at high disability risk.

Small vessel disease and clinical outcomes after IV rt-PA treatment

INTRODUCTION

Cerebral small vessel disease (SVD) contributes to dementia and disability in the elderly, and may negatively affect stroke outcomes. We aimed to evaluate to what extent single features and global burden of SVD detected with magnetic resonance (MR) are associated with worse outcomes in patients with ischaemic stroke treated with intravenous thrombolysis.

METHODS

We accessed anonymized data and MR images from the Stroke Imaging Repository (STIR) and the Virtual International Stroke Trials Archive (VISTA) Imaging. We described SVD features using validated scales and quantified the global burden of SVD with a combined score. Our mainoutcome was the modified Rankin Scale (mRS) at 90 days after stroke. We used logistic regression and ordinal regression models (adjusted for age, sex, stroke severity, onset to treatment time) to examine the associations between each SVD feature, SVD global burden and clinical outcomes.

RESULTS

A total of 259 patients had MR scans available at baseline (mean age±SD=68.7±15.5 years; 131 [49%] males). After adjustment for confounders, severe white matter changes were associated with disability (OR=5.14; 95%CI=2.30-11.48), functional dependency (OR=4.38; 95%CI=2.10-9.13) and worse outcomes in ordinal analysis (OR=2.71; 95%CI=1.25-5.85). SVD score was associated with disability (OR=1.66; 95%CI=1.03-2.66) and functional dependency (OR=1.47; 95%CI=1.00-2.45). Lacunes, enlarged perivascular spaces and brain atrophy showed no association with clinical outcomes.

CONCLUSION

Our results suggest that SVD negatively affects stroke outcomes after intravenous thrombolysis. Although white matter changes seem to be the major driver in relation to worse outcomes, global estimation of SVD is feasible and may provide helpful information.

Leukoaraiosis, intracerebral hemorrhage, and functional outcome after acute stroke thrombolysis

Objective:

To perform a systematic review and pooled meta-analysis of published studies to assess whether the presence of leukoaraiosis on neuroimaging before treatment with thrombolysis (IV or intra-arterial) is associated with an increased risk of symptomatic intracerebral hemorrhage (sICH) or poor functional outcome.

Methods:

We included studies of patients with acute ischemic stroke, treated with IV or intra-arterial thrombolysis, which assessed functional outcome (3-month modified Rankin Scale [mRS]) or sICH in relation to leukoaraiosis on pretreatment neuroimaging (CT or MRI). We used random-effects models to calculate pooled relative risks (RR) of sICH and poor functional outcome (mRS ≥ 2) for any vs no leukoaraiosis (using any rating scale) and for no to mild vs moderate to severe leukoaraiosis (using the Van Swieten or Fazekas Schmidt scale).

Results:

We identified 15 studies (total n = 6,967). For sICH outcome, the RR was 1.65 (n = 5,551; 95% confidence interval [CI] 1.26–2.16, p = 0.001) with an absolute risk (AR) increase of 2.5% for any leukoaraiosis vs none. The RR was 2.4 (n = 4,192; 95% CI 1.83–3.14, p = 0.001) with an AR increase of 6.2% for moderate to severe vs no to mild leukoaraiosis. For poor functional outcome; the RR was 1.30 (n = 3,401; 95% CI 1.19–1.42, p = 0.001) with an AR increase of 15.4% for any leukoaraiosis vs none. The RR was 1.31 (n = 3,659; 95% CI 1.22–1.42, p = 0.001) with an AR increase of 17.5% for moderate to severe vs no to mild leukoaraiosis. No statistical heterogeneity was noted for any of the analyses.

Conclusions:

Leukoaraiosis presence and severity are consistently associated with an increased risk of sICH and poor functional outcome after IV or intra-arterial thrombolysis for acute ischemic stroke.

Association between the extent of white matter damage and early cognitive impairment following acute ischemic stroke

White matter (WM) injury following acute ischemic stroke (AIS) is associated with cognitive decline. Establishing relationships between the specific cognitive tests used to assess post-AIS cognition and various clinical indices of WM injury severity and distribution may aid in prognosis and early treatment decisions. We enrolled 62 patients with AIS to Weifang People's Hospital between September 2014 and August 2015. WM lesion severity and distribution were examined by computed tomography (CT) and magnetic resonance imaging (MRI). The Blennow scale was used for scoring the distribution and degree of WM lesions (WMLs) on CT images, the Fazekas scale for scoring periventricular and deep WMLs on MRI, and the Cholinergic Pathways Hyperintensities Scale (CHIPS) for scoring MRI manifestation of cholinergic fiber damage. The 8-domain Montreal Cognitive Assessment (MoCA) was used to evaluate cognitive function. Mean ± standard deviation scores on the Blennow scale was 1.6±0.5; Fazekas scale, 3.4±0.8; and CHIPS, 65.7±12.5. The proportion of patients with a MoCA score <26 (indicating cognitive dysfunction) was significantly higher in subgroups with Blennow scale score >2, Fazekas scale score >4, and CHIPS score >51 (all P<0.001). The MoCA score was negatively correlated with Blennow scale score (r=−0.326, P=0.002), Fazekas scale score (r=−0.404, P=0.031), and CHIPS score (r=−0.234, P=0.042). Thus, the degree and distribution of whole-brain, deep, and cholinergic WMLs were associated with cognitive impairment. The Blennow scale, Fazekas scale, and CHIPS all provide good predictive efficacy of post-AIS cognitive dysfunction.

Leukoaraiosis, Cerebral Hemorrhage, and Outcome After Intravenous Thrombolysis for Acute Ischemic Stroke: A Meta-Analysis (v1)

BACKGROUND AND PURPOSE

We performed a meta-analysis to assess whether leukoaraiosis on brain computed tomographic scans of acute ischemic stroke patients treated with intravenous thrombolysis is associated with an increased risk of symptomatic intracerebral hemorrhage (sICH) or poor functional outcome at 3 to 6 months after stroke, or both.

METHODS

We searched PubMed and pooled relevant data in meta-analyses using random effects models. Using odds ratios (OR), we quantified the strength of association between the presence and severity of leukoaraiosis and post-thrombolysis sICH or 3- to 6-month modified Rankin Score >2.

RESULTS

Eleven eligible studies (n=7194) were pooled in meta-analysis. The risk of sICH was higher in patients with leukoaraiosis (OR, 1.55; 95% confidence interval [CI], 1.17-2.06; P=0.002) and severe leukoaraiosis (OR, 2.53; 95% CI, 1.92-3.34; P<0.0001) compared with patients without leukoaraiosis. Leukoaraiosis was an independent predictor of sICH in 6 included studies (n=4976; adjusted OR, 1.75; 95% CI, 1.35-2.27; P<0.0001). OR for leukoaraiosis and poor 3- to 6-month outcome was 2.02 (95% CI, 1.54-2.65; P<0.0001), with significant statistical heterogeneity (I(2), 75.7%; P=0.002). In adjusted analyses, leukoaraiosis was an independent predictor of poor outcome (n=3688; adjusted OR, 1.61; 95% CI, 1.44-1.79; P<0.0001). In post hoc analyses, including only leukoaraiosis patients in randomized controlled trials (IST-3 [third International Stroke Trial], NINDS [National Institute of Neurological Disorders and Stroke], ECASS-1-2 [European Cooperative Acute Stroke Study]; n=2234), tissue-type plasminogen activator versus control was associated with higher sICH risk (OR, 5.50; 95% CI, 2.49-12.13), but lower poor outcome risk (OR, 0.75; 95% CI, 0.60-0.95).

CONCLUSIONS

Leukoaraiosis might increase post-intravenous thrombolysis sICH risk and poor outcome poststroke. Despite increased sICH risk, intravenous tissue-type plasminogen activator treatment has net clinical benefit in patients with leukoaraiosis. Given the risk of bias/confounding, these results should be considered hypothesis-generating and do not justify withholding intravenous thrombolysis.

Impact of leukoaraiosis on parenchymal hemorrhage in elderly patients treated with thrombolysis

INTRODUCTION

Severity of vascular damage of white matter may predict hemorrhagic transformation (HT). We assess the relationship between leukoaraiosis (LA) severity and the type of hemorrhagic transformation in elderly patients treated with thrombolysis.

METHODS

We retrospectively analyzed the clinical data and pretreatment magnetic resonance imaging (MRI) of 180 consecutive ischemic stroke patients aged over 75 years. LA severity was graded according to the Fazekas scale, and acute diffusion-weighted-imaging (DWI) lesion volumes were semi-automatically outlined. Predictors of hemorrhagic infarction (HI) and parenchymal hemorrhage (PH) were identified using logistic regression analysis and exact multinomial logistic analysis.

RESULTS

HT occurred in 31 patients (17 %). Baseline National Institute of Health Stroke Score (NIHSS; p = 0.008), severe LA (p = 0.02), and diffusion lesion volume (p = 0.02) were predictors of HT in univariable logistic regression. Adjusted to lesion volume and baseline NIHSS score, exact multinomial logistic analysis showed that severe LA was the only independent predictor of parenchymal hemorrhage (p = 0.03).

CONCLUSION

In elderly patients, LA severity better predicts parenchymal hemorrhage than infarct size.

White matter injury in ischemic stroke

Stroke is one of the major causes of disability and mortality worldwide. It is well known that ischemic stroke can cause gray matter injury. However, stroke also elicits profound white matter injury, a risk factor for higher stroke incidence and poor neurological outcomes. The majority of damage caused by stroke is located in subcortical regions and, remarkably, white matter occupies nearly half of the average infarct volume. Indeed, white matter is exquisitely vulnerable to ischemia and is often injured more severely than gray matter. Clinical symptoms related to white matter injury include cognitive dysfunction, emotional disorders, sensorimotor impairments, as well as urinary incontinence and pain, all of which are closely associated with destruction and remodeling of white matter connectivity. White matter injury can be noninvasively detected by MRI, which provides a three-dimensional assessment of its morphology, metabolism, and function. There is an urgent need for novel white matter therapies, as currently available strategies are limited to preclinical animal studies. Optimal protection against ischemic stroke will need to encompass the fortification of both gray and white matter. In this review, we discuss white matter injury after ischemic stroke, focusing on clinical features and tools, such as imaging, manifestation, and potential treatments. We also briefly discuss the pathophysiology of WMI and future research directions.

Increased Risk of Post-Thrombolysis Intracranial Hemorrhage in Acute Ischemic Stroke Patients with Leukoaraiosis: A Meta-Analysis

Background

Leukoaraiosis is common in patients with acute ischemic stroke. The results from many studies investigating the association between leukoaraiosis and intracranial hemorrhage after thrombolysis remain conflicting.

Methods

A meta-analysis was performed to compare the risk of post-thrombolytic intracranial hemorrhage in patients with and without leukoaraiosis. Relevant reports were identified by searching PubMed, EmBase, Cochrane Library, and ISI Web of Science through December 2015 using a combination of subjective and random terms. Eligible studies that were original articles with a clear definition of leukoaraiosis and intracranial hemorrhage were selected and analyzed. Funnel plots, Egger’s test, and Begg’s test were conducted to assess the publication bias. Sensitivity analysis was also performed to evaluate the influence of each individual study.

Results

Eleven trials that enrolled 6912 participants were included. There was a significantly increased risk for acute ischemic stroke patients with leukoaraiosis (odds ratio: 1.89, 95% confidence interval 1.51–2.37, P<0.001). Low heterogeneity and less publication bias was detected among these studies. The results of both computed tomography and magnetic resonance imaging performed on the subgroups of leukoaraiosis were significant. Furthermore, an association between leukoaraiosis and symptomatic intracranial hemorrhage was also confirmed. The odds ratios remained stable with no obvious variations on the sensitivity analysis. The limitations consisted of types of including trials and not matching some baseline variables.

Conclusions

The results of this meta-analysis show that leukoaraiosis approximately doubles the incidence of intracranial hemorrhage after thrombolytic therapy. However, it does not critically affect decision making regarding thrombolysis for patients with acute ischemic stroke. Additional investigations are required.

White Matter Lesions Double the Risk of Post-Thrombolytic Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Cerebral white matter lesions (WMLs), a surrogate for small-vessel disease, are common in patients with stroke and may be related to an increased intracranial bleeding risk after intravenous thrombolysis in acute ischemic stroke. We aimed to investigate the risk of symptomatic intracerebral hemorrhage (sICH) in the presence of WMLs in a large cohort of ischemic stroke patients treated with intravenous thrombolysis.

METHODS

We included 2485 consecutive patients treated with intravenous thrombolysis at the Helsinki University Central Hospital. WMLs were scored according to 4 previously published computed tomography visual rating scales from all baseline head scans. A sICH was classified according to the European Cooperative Acute Stroke Study II criteria. The associations of sICH with nominal, ordinal, and continuous variables were analyzed in a univariate binary regression model and adjusted in multivariate binary regression models.

RESULTS

In univariate and multivariate regression analyses, all 4 tested visual WML rating scales (as continuous variables or dichotomized at different cutoff points) were associated with increased risk of sICH. In binary analyses, WML doubled the bleeding risk: the odds ratios of all 4 visual rating scales ranged from 2.22 (95% confidence interval, 1.49-3.30) to 2.70 (1.87-3.90) in univariable and from 2.00 (1.26-3.16) to 2.62 (1.71-4.02) in multivariable analyses. The multivariable-adjusted odds ratio for the association of high load of WMLs with remote parenchymal hemorrhage was 4.11 (2.38-7.10).

CONCLUSIONS

WMLs visible on computed tomography are associated with a more than doubled risk of sICH in patients treated with intravenous thrombolysis for acute ischemic stroke.