Ischemic lesion volumes in acute stroke by diffusion-weighted magnetic resonance imaging correlate with clinical outcome

Neglect scoring modifications in the National Institutes of Health Stroke Scale improve right hemisphere stroke lesion volume prediction

BACKGROUND

The National Institutes of Health Stroke Scale (NIHSS) does not equitably assess stroke severity in the two cerebral hemispheres. By attributing a maximum of two points for neglect and seven for language, it undervalues right hemisphere deficits. We aimed to investigate if NIHSS equally predicts right hemisphere lesion volumes in patients with and without neglect, and if a modification of the neglect scoring rules could increase its predictive capacity.

METHODS

We analyzed a prospective cohort of acute right middle cerebral artery ischemic stroke patients. First, we calculated the correlation between NIHSS scores and lesion volume and analyzed the partial correlation of neglect. Then, we applied different modifications in the neglect scoring rules and investigated how they interfered with lesion volume predictive capacity.

RESULTS

A total of 162 ischemic stroke patients were included, 108 with neglect and 54 without. The correlation between lesion volume and NIHSS was lower in patients with neglect (r = 0.540 vs. r = 0.219, p = 0.004) and neglect was a statistically significant covariate in the partial correlation analysis between NIHSS and lesion volume (p = 0.017). With the neglect score tripled and with the duplication or triplication of all neglect modalities, the correlation was significantly higher than with the standard NIHSS (p = 0.043, p = 0.005, p = 0.001, respectively). With these modifications, neglect was no longer a significant covariable in the partial correlation between lesion volume and NIHSS.

CONCLUSION

A modification of NIHSS neglect scoring might improve the scale's capacity to predict lesion volume.

Mapping the Glymphatic Pathway Using Imaging Advances

The glymphatic system is a newly discovered waste-clearing system that is analogous to the lymphatic system in our central nervous system. Furthermore, disruption in the glymphatic system has also been associated with many neurodegenerative disorders (e.g., Alzheimer's disease), traumatic brain injury, and subarachnoid hemorrhage. Thus, understanding the function and structure of this system can play a key role in researching the progression and prognoses of these diseases. In this review article, we discuss the current ways to map the glymphatic system and address the advances being made in preclinical mapping. As mentioned, the concept of the glymphatic system is relatively new, and thus, more research needs to be conducted in order to therapeutically intervene via this system.

Clinico-topographic evaluation of anterior versus posterior acute ischemic stroke and correlation with early mortality-based scale prediction

Objective

Posterior circulation ischaemic strokes (PCIs) are a clinical syndrome associated with ischemia related to stenosis, in situ thrombosis, or embolic occlusion of the posterior circulation and differ from anterior circulation ischaemic strokes (ACIs) in many aspects. In this study, ACIs and PCIs were evaluated in terms of clinico-radiological and demographic aspects, and the relevance of objective scales to early disability and mortality was investigated.

Methods

The definition of ACIS or PCIS was classified according to the Oxfordshire Community Stroke Project (OCSP). There are mainly two groups divided into ACIs and PCIs. ACIs were included as total anterior circulation syndrome (TACS), partial anterior circulation syndrome (PACS) (right and left), and lacunar syndrome (LACS) (right and left), and PCIs were posterior circulation syndrome (POCS) (right and left). Arrival NIH Stroke Scale/Score (NIHSS) and Glasgow Coma Scale (GCS) scores were evaluated in clinical assessment and modified SOAR Score for Stroke (mSOAR) was for early mortality-based scale prediction. All data were compared, and mean, IQR (if applicable) values and ROC curve analysis were determined.

Results

A total of 100 AIS patients, 50 of whom were ACIs and 50 were PCIs, were included in the study and were evaluated within the first 24 h. Hypertension was the most common disease for both groups. The second most common was hyperlipidemia (82%) in the ACIs and diabetes mellitus (40%) in the PCIs. The frequency of right hemisphere ischemia was higher in ACIs (63.6%) and PCIs (48%). The mean NIHSS and GCS score (also median IQR) was higher in the right ACIs and the highest NIHSS mean was in the right partial anterior circulation syndrome (PACS) (respectively median (IQR): 9.5 (13) and median (IQR):14.5 (3)). The mean NIHSS and GCS score of bilateral posterior circulation syndrome (POCS) were the highest in PCIs (median (IQR):3 (17), (IQR):15 (4) respectively). The mSOAR mean was the highest in the right PACS in ACIs (median (IQR):2.5 (2)) and in bilateral POCs among PCIs (median(IQR):2(2)).

Conclusion

The association of PCIs with hyperlipidemia and the male gender was interpreted, and anterior infarcts were found to cause higher early clinical disability scores. The NIHSS scale was effective and reliable, especially in anterior acute strokes, but also emphasized the necessity of using the GCS assessment together in the first 24 h in the assessment of PCIs. mSOAR scale is a helpful predictor in estimating early mortality not only in ACIs but also in PCIs, similar to GCS.

Neural bases characterizing chronic and severe upper-limb motor deficits after brain lesion

Chronic and severe upper-limb motor deficits can result from damage to the corticospinal tract. However, it remains unclear what their characteristics are and whether only corticospinal tract damage determines their characteristics. This study aimed to investigate the clinical characteristics and neural bases of chronic and severe upper-limb motor deficits. Motor deficits, including spasticity, of 45 patients with brain lesions were assessed using clinical scales. Regarding their scores, we conducted a principal component analysis that statistically extracted the clinical characteristics as two principal components. Using these principal components, we investigated the neural bases underlying their characteristics through lesion analyses of lesion volume, lesion sites, corticospinal tract, or other regional white-matter integrity. Principal component analysis showed that the clinical characteristics of chronic and severe upper-limb motor deficits could be described as a comprehensive severity and a trade-off relationship between proximal motor functions and wrist/finger spasticity. Lesion analyses revealed that the comprehensive severity was correlated with corticospinal tract integrity, and the trade-off relationship was associated with the integrity of other regional white matter located anterior to the posterior internal capsule, such as the anterior internal capsule. This study indicates that the severity of chronic and severe upper-limb motor deficits can be determined according to the corticospinal tract integrity, and such motor deficits may be further characterized by the integrity of other white matter, where the corticoreticular pathway can pass through, by forming a trade-off relationship where patients have higher proximal motor functions but more severe wrist/finger spasticity, and vice versa.

Deep profiling of multiple ischemic lesions in a large, multi-center cohort: Frequency, spatial distribution, and associations to clinical characteristics

Background purpose

A substantial number of patients with acute ischemic stroke (AIS) experience multiple acute lesions (MAL). We here aimed to scrutinize MAL in a large radiologically deep-phenotyped cohort.

Materials and methods

Analyses relied upon imaging and clinical data from the international MRI-GENIE study. Imaging data comprised both Fluid-attenuated inversion recovery (FLAIR) for white matter hyperintensity (WMH) burden estimation and diffusion-weighted imaging (DWI) sequences for the assessment of acute stroke lesions. The initial step featured the systematic evaluation of occurrences of MAL within one and several vascular supply territories. Associations between MAL and important imaging and clinical characteristics were subsequently determined. The interaction effect between single and multiple lesion status and lesion volume was estimated by means of Bayesian hierarchical regression modeling for both stroke severity and functional outcome.

Results

We analyzed 2,466 patients (age = 63.4 ± 14.8, 39% women), 49.7% of which presented with a single lesion. Another 37.4% experienced MAL in a single vascular territory, while 12.9% featured lesions in multiple vascular territories. Within most territories, MAL occurred as frequently as single lesions (ratio ∼1:1). Only the brainstem region comprised fewer patients with MAL (ratio 1:4). Patients with MAL presented with a significantly higher lesion volume and acute NIHSS (7.7 vs. 1.7 ml and 4 vs. 3, p FDR < 0.001). In contrast, patients with a single lesion were characterized by a significantly higher WMH burden (6.1 vs. 5.3 ml, p FDR = 0.048). Functional outcome did not differ significantly between patients with single versus multiple lesions. Bayesian analyses suggested that the association between lesion volume and stroke severity between single and multiple lesions was the same in case of anterior circulation stroke. In case of posterior circulation stroke, lesion volume was linked to a higher NIHSS only among those with MAL.

Conclusion

Multiple lesions, especially those within one vascular territory, occurred more frequently than previously reported. Overall, multiple lesions were distinctly linked to a higher acute stroke severity, a higher total DWI lesion volume and a lower WMH lesion volume. In posterior circulation stroke, lesion volume was linked to a higher stroke severity in multiple lesions only.

MRI whole-lesion texture analysis on ADC maps for the prognostic assessment of ischemic stroke

Background

This study aims is to explore whether it is feasible to use magnetic resonance texture analysis (MRTA) in order to distinguish favorable from unfavorable function outcomes and determine the prognostic factors associated with favorable outcomes of stroke.

Methods

The retrospective study included 103 consecutive patients who confirmed unilateral anterior circulation subacute ischemic stroke by computed tomography angiography between January 2018 and September 2019. Patients were divided into favorable outcome (modified Rankin scale, mRS ≤ 2) and unfavorable outcome (mRS > 2) groups according to mRS scores at day 90. Two radiologists manually segmented the infarction lesions based on diffusion-weighted imaging and transferred the images to corresponding apparent diffusion coefficient (ADC) maps in order to extract texture features. The prediction models including clinical characteristics and texture features were built using multiple logistic regression. A univariate analysis was conducted to assess the performance of the mean ADC value of the infarction lesion. A Delong’s test was used to compare the predictive performance of models through the receiver operating characteristic curve.

Results

The mean ADC performance was moderate [AUC = 0.60, 95% confidence interval (CI) 0.49–0.71]. The texture feature model of the ADC map (tADC), contained seven texture features, and presented good prediction performance (AUC = 0.83, 95%CI 0.75–0.91). The energy obtained after wavelet transform, and the kurtosis and skewness obtained after Laplacian of Gaussian transformation were identified as independent prognostic factors for the favorable stroke outcomes. In addition, the combination of the tADC model and clinical characteristics (hypertension, diabetes mellitus, smoking, and atrial fibrillation) exhibited a subtly better performance (AUC = 0.86, 95%CI 0.79–0.93; P > 0.05, Delong’s).

Conclusion

The models based on MRTA on ADC maps are useful to evaluate the clinical function outcomes in patients with unilateral anterior circulation ischemic stroke. Energy obtained after wavelet transform, kurtosis obtained after Laplacian of Gaussian transform, and skewness obtained after Laplacian of Gaussian transform were identified as independent prognostic factors for favorable stroke outcomes.

Primer reporte de inmaduros de Cryptocephalus Geoffroy, 1762 (Coleoptera: Chrysomelidae) de Brasil con notas de su bioecología sobre Wedelia goyazensis Gardner (Asteraceae) y síntesis de los registros de presencia del género en territorio brasileño

Cryptocephalus Geoffroy, 1762 es reconocido por su distribución cosmopolita y gran riqueza, con al menos 1700 especies descritas. Sin embargo, falta información para Brasil: (1) no hay registro de inmaduros; y (2) no se conoce casi nada sobre la biología de este género. En este trabajo se documentan por primera vez las etapas inmaduras de Cryptocephalus de Brasil y se presentan algunas notas sobre su bioecología en la planta huésped. Además, se recopilan sus registros en territorio brasileño a partir de la bibliografía.

Cortical Thickness of Brain Areas Beyond Stroke Lesions and Sensory-Motor Recovery: A Systematic Review

Background: The clinical outcome of patients suffering from stroke is dependent on multiple factors. The features of the lesion itself play an important role but clinical recovery is remarkably influenced by the plasticity mechanisms triggered by the stroke and occurring at a distance from the lesion. The latter translate into functional and structural changes of which cortical thickness might be easy to quantify one of the main players. However, studies on the changes of cortical thickness in brain areas beyond stroke lesion and their relationship to sensory-motor recovery are sparse. Objectives: To evaluate the effects of cerebral stroke on cortical thickness (CT) beyond the stroke lesion and its association with sensory-motor recovery. Materials and Methods: Five electronic databases (PubMed, Embase, Web of Science, Scopus and the Cochrane Library) were searched. Methodological quality of the included studies was assessed with the Newcastle-Ottawa Scale for non-randomized controlled trials and the Risk of Bias Cochrane tool for randomized controlled trials. Results: The search strategy retrieved 821 records, 12 studies were included and risk of bias assessed. In most of the included studies, cortical thinning was seen at the ipsilesional motor area (M1). Cortical thinning can occur beyond the stroke lesion, typically in regions anatomically connected because of anterograde degeneration. Nonetheless, studies also reported cortical thickening of regions of the unaffected hemisphere, likely related to compensatory plasticity. Some studies revealed a significant correlation between changes in cortical thickness of M1 or somatosensory (S1) cortical areas and motor function recovery. Discussion and Conclusions: Following a stroke, changes in cortical thickness occur both in regions directly connected to the stroke lesion and in contralateral hemisphere areas as well as in the cerebellum. The underlying mechanisms leading to these changes in cortical thickness are still to be fully understood and further research in the field is needed. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020200539; PROSPERO 2020, identifier: CRD42020200539.

Emergency Care of Patients with Acute Ischemic Stroke

Stroke is a leading cause of morbidity and mortality and a major cause of long-term disability. Management of acute ischemic stroke in the first hours is critical to patient outcomes. This review provides an overview of acute ischemic stroke management, with a focus on the golden hour. Additional topics discussed include prehospital considerations and initial evaluation of the patient with history, examination, and imaging as well as treatment options, including thrombolysis and endovascular therapy.

Grey and white matter network disruption is associated with sensory deficits after stroke

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Somatosensory deficits occur in about 60% of patients after ischaemic stroke.

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Clinical and imaging data of 101 ischaemic stroke patients were analysed.

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Stroke lesions may disrupt grey (GM) and/or white matter (WM) network.

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Lesion volume explains 23% of sensory deficit variance; GM / WM disruption adds 14%

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Subnetwork of postcentral, supramarginal, transverse temporal gyri involved.

Somatosensory deficits after ischaemic stroke are common and can occur in patients with lesions in the anterior parietal cortex and subcortical nuclei. It is less clear to what extent damage to white matter tracts within the somatosensory system may contribute to somatosensory deficits after stroke. We compared the roles of cortical damage and disruption of subcortical white matter tracts as correlates of somatosensory deficit after ischaemic stroke.

Clinical and imaging data were assessed in incident stroke patients. Somatosensory deficits were measured using a standardized somatosensory test. Remote effects were quantified by projecting the MRI-based segmented stroke lesions onto a predefined atlas of white matter connectivity. Direct ischaemic damage to grey matter was computed by lesion overlap with grey matter areas. The association between lesion impact scores and sensory deficit was assessed statistically.

In 101 patients, median sensory score was 188/193 (97.4%). Lesion volume was associated with somatosensory deficit, explaining 23.3% of variance. Beyond this, the stroke-induced grey and white matter disruption within a subnetwork of the postcentral, supramarginal, and transverse temporal gyri explained an additional 14% of the somatosensory outcome variability. On mutual comparison, white matter network disruption was a stronger predictor than grey matter damage.

Ischaemic damage to both grey and white matter are structural correlates of acute somatosensory disturbance after ischaemic stroke. Our data suggest that white matter integrity of a somatosensory network of primary and secondary cortex is a prerequisite for normal processing of somatosensory inputs and might be considered as an additional parameter for stroke outcome prediction in the future.

Disconnectomics of the Rich Club Impacts Motor Recovery After Stroke

BACKGROUND AND PURPOSE

Structural brain networks possess a few hubs, which are not only highly connected to the rest of the brain but are also highly connected to each other. These hubs, which form a rich-club, play a central role in global brain organization. To investigate whether the concept of rich-club sheds new light on poststroke recovery, we applied a novel network-theoretical quantification of lesions to patients with stroke and compared the outcomes with what lesion size alone would indicate.

METHODS

Whole-brain structural networks of 73 patients with ischemic stroke were reconstructed using diffusion-weighted imaging data. Disconnectomes, a new type of network analyses, were constructed using only those fibers that pass through the lesion. Fugl-Meyer upper extremity scores and their changes were used to determine whether the patients show natural recovery or not.

RESULTS

Cluster analysis revealed 3 patient clusters: small-lesion-good-recovery, midsized-lesion-poor-recovery (MLPR), and large-lesion-poor-recovery (LLPR). The small-lesion-good-recovery consisted of subjects whose lesions were small, and whose prospects for recovery were relatively good. To explain the nondifference in recovery between the MLPR and LLPR clusters despite the difference (LLPR>MLPR) in lesion volume, we defined the [Formula: see text] metric to be the sum of the entries in the disconnectome and, more importantly, the [Formula: see text] to be the sum of all entries in the disconnectome corresponding to edges with at least one node in the rich-club. Unlike lesion volume and corticospinal tract damage (MLPR<LLPR), for [Formula: see text], this relationship was reversed (MLPR>LLPR) or showed no difference for [Formula: see text].

CONCLUSIONS

Smaller lesions that focus on the rich-club can be just as devastating as much larger lesions that do not focus on the rich-club, pointing to the role of the rich-club as a backbone for functional communication within brain networks and for recovery from stroke.

Prognostic Value of a Structural Brain MRI Score in the Acute Phase of Aneurysmal Subarachnoid Hemorrhage: A Pilot Study

BACKGROUND/OBJECTIVE

Aneurysmal subarachnoid hemorrhage (aSAH) is associated with high morbidity and mortality despite advances in management. We evaluated the prognostic significance of a qualitative score using brain magnetic resonance imaging (MRI) features obtained early after aSAH.

METHODS

Patients with aSAH were enrolled in a prospective observational cohort and underwent brain MRI during their acute hospitalization. MRIs were rated using a scoring system that considers the anatomical location of signal intensity changes on diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) sequences. The relationship between MRI scores and functional outcome defined by modified Rankin scale (mRS) at 6 months was evaluated in uni- and multivariable models.

RESULTS

The cohort included 45 aSAH patients (median World Federation of Neurologic Surgeons (IQR) 2 (1-4)) who underwent brain MRI a mean (SD) of 9.0 ± 8.0 days after aSAH. At 6 months after aSAH, 26 patients had achieved a favorable outcome (mRS ≤ 2) while 15 had an unfavorable outcome (mRS > 2). Deep gray nuclei (DGN) score (p = 0.016), cortex + DGN score (p = 0.015), FLAIR score (p = 0.016), DWI score (p = 0.0045), and overall score (p = 0.0081) were significantly lower in patients with favorable outcome compared to those with unfavorable outcome. However, MRI scores were not independent predictors of outcome in multivariable models adjusting for admission Hunt and Hess, Glasgow Coma Scale, or World Federation of Neurologic Surgeons scales.

CONCLUSIONS

In this pilot study, a qualitative scoring system using anatomically defined MRI FLAIR and DWI signal abnormalities identified in the acute phase of aSAH was linked to 6-month functional outcome. However, these scores did not add prognostic value to established indices of neurological severity.

Exploring the predictive value of lesion topology on motor function outcomes in a porcine ischemic stroke model

Harnessing the maximum diagnostic potential of magnetic resonance imaging (MRI) by including stroke lesion location in relation to specific structures that are associated with particular functions will likely increase the potential to predict functional deficit type, severity, and recovery in stroke patients. This exploratory study aims to identify key structures lesioned by a middle cerebral artery occlusion (MCAO) that impact stroke recovery and to strengthen the predictive capacity of neuroimaging techniques that characterize stroke outcomes in a translational porcine model. Clinically relevant MRI measures showed significant lesion volumes, midline shifts, and decreased white matter integrity post-MCAO. Using a pig brain atlas, damaged brain structures included the insular cortex, somatosensory cortices, temporal gyri, claustrum, and visual cortices, among others. MCAO resulted in severely impaired spatiotemporal gait parameters, decreased voluntary movement in open field testing, and higher modified Rankin Scale scores at acute timepoints. Pearson correlation analyses at acute timepoints between standard MRI metrics (e.g., lesion volume) and functional outcomes displayed moderate R values to functional gait outcomes. Moreover, Pearson correlation analyses showed higher R values between functional gait deficits and increased lesioning of structures associated with motor function, such as the putamen, globus pallidus, and primary somatosensory cortex. This correlation analysis approach helped identify neuroanatomical structures predictive of stroke outcomes and may lead to the translation of this topological analysis approach from preclinical stroke assessment to a clinical biomarker.

A randomized trial comparing axillary versus innominate artery cannulation for aortic arch surgery

BACKGROUND

Cerebral protection remains the cornerstone of successful aortic surgery; however, there is no consensus as to the optimal strategy.

OBJECTIVE

To compare the safety and efficacy of innominate to axillary artery cannulation for delivering antegrade cerebral protection during proximal aortic arch surgery.

METHODS

This randomized controlled trial (The Aortic Surgery Cerebral Protection Evaluation CardioLink-3 Trial, ClinicalTrials.gov Identifier: NCT02554032), conducted across 6 Canadian centers between January 2015 and June 2018, allocated 111 individuals to innominate or axillary artery cannulation. The primary safety outcome was neuroprotection per the appearance of new severe ischemic lesions on the postoperative diffusion-weighted-magnetic resonance imaging. The primary efficacy outcome was the difference in total operative time. Secondary outcomes included 30-day all-cause mortality and postoperative stroke.

RESULTS

One hundred two individuals (mean age, 63 ± 11 years) were in the primary safety per-protocol analysis. Baseline characteristics between the groups were similar. New severe ischemic lesions occurred in 19 participants (38.8%) in the axillary versus 18 (34%) in the innominate group (P for noninferiority = .0009). Total operative times were comparable (median, 293 minutes; interquartile range, 222-411 minutes) for axillary versus (298 minutes; interquartile range, 231-368 minutes) for innominate (P for superiority = .47). Stroke/transient ischemic attack occurred in 4 (7.1%) participants in the axillary versus 2 (3.6%) in the innominate group (P = .43). Thirty-day mortality, seizures, delirium, and duration of mechanical ventilation were similar in both groups.

CONCLUSIONS

diffusion-weighted magnetic resonance imaging assessments indicate that antegrade cerebral protection with innominate cannulation is safe and affords similar neuroprotection to axillary cannulation during aortic surgery, although the burden of new neurological lesions is high in both groups.

Normalized wall index, intraplaque hemorrhage and ulceration of carotid plaques correlate with the severity of ischemic stroke

BACKGROUND AND AIMS

Carotid atherosclerosis is considered an important cause of ischemic stroke. Tthis study aimed to explore the relationship between plaque features and the severity of stroke, and to identify plaque risk factors for the assessment of the severity of ischemic stroke.

METHODS

Symptomatic patients with carotid atherosclerotic plaques were prospectively recruited and underwent high-resolution vessel wall magnetic resonance imaging (VW-MRI). Two trained MRI readers independently identified intraplaque hemorrhage (IPH), calcification (CA), surface CA, deep CA, and ulceration. They measured and calculated the maximum vessel diameter (Max VD), maximum wall thickness (Max WT), total vessel area, lumen area, normalized wall index (NWI), plaque volume, IPH volume, IPH proportion, CA volume, and CA proportion. Patients were divided into two groups according to their National Institutes of Health Stroke Scale (NIHSS) scores (NIHSS ≤1 vs. NIHSS >1). Clinical characteristics and carotid plaque features were compared using the Mann-Whitney U test or Chi-square test as appropriate. Odds ratio (OR) and corresponding 95% confidence interval (CI) of plaque features to distinguish patients with NIHSS >1 were calculated. Spearman's rank correlations or Pearson correlations were determined for plaque features and NIHSS scores.

RESULTS

Of the 97 included patients, 34 (35.05%) with NIHSS >1 had significantly greater NWI (p < 0.05), larger IPH volume (p < 0.01), and greater IPH proportion (p < 0.01), and higher prevalence of IPH (OR, 5.654; 95%CI, 2.272-14.070; p < 0.01) and ulceration (OR, 2.891; 95%CI, 1.090-7.667; p = 0.033) than patients with NIHSS ≤1. Max WT (r = 0.24, p = 0.018), NWI (r = 0.22, p = 0.032), IPH (r = 0.27, p = 0.007), IPH volume (r = 0.35, p < 0.01), IPH proportion (r = 0.28, p = 0.005), and ulceration (r = 0.35, p < 0.01) had positive correlations with NIHSS scores.

CONCLUSIONS

NWI, IPH, and ulceration of carotid atherosclerotic plaque based on high-resolution VW-MRI may be useful indicators for assessing the severity of ischemic stroke in patients with atherosclerosis. NIHSS score is related to max WT, NWI, IPH, IPH volume, IPH proportion, and ulceration.

Post-stroke ASPECTS predicts outcome after thrombectomy

PURPOSE

Infarct growth and final infarct volume are established outcome modifiers following endovascular thrombectomy (EVT) for patients with large vessel occlusion stroke (LVO). Simple techniques for final infarct volume measurement are lacking, and therefore, we tested whether post-EVT ASPECTS can be used for prognostic evaluation after EVT.

METHODS

Infarct size at baseline was measured in a prospective cohort of patients with LVO that underwent EVT with the ASPECTS score on admission non-contrast CT. Final infarct size was assessed with a post-EVT ASPECTS (ASPECTS-POST) obtained from a follow-up CT 24-72 h post-EVT. The best performing ASPECTS-POST was chosen based on comparisons of different thresholds. Outcome measures included survival rates and modified Rankin Score at 90 days.

RESULTS

A total of 272 patients were included and 166 of them had an ASPECTS-POST ≥ 7. ASPECTS-POST ≥ 7 was associated with increased likelihood of favorable outcome at 90 days (67% vs. 21%, p < 0.001) with sensitivity, specificity, and positive and negative predictive values of 86%, 58%, 61%, and 85%, respectively. On multivariate analysis, ASPECTS-POST ≥ 7 was found to be a significant modifier of favorable outcome (Odds Ratio [OR] 6.2, 95% confidence intervals [CI] 3.1-12.4) and survival (OR 5.8 95% CI 2.4-14.3).

CONCLUSION

ASPECTS can be rapidly and easily obtained from the post-EVT NCCT and ASPECTS-POST ≥ 7 correlates with good outcome.

Can diffusion tensor imaging lesion patterns predict the outcome of ischemic stroke?

Background

Stroke can affect any portion of the central nervous system leading to a wide variety of symptoms depending on the part that is involved. Diffusion tensor imaging (DTI) is an emerging neuroimaging technique that allows measuring the integrity of white matter tracts.

Objectives

The objective of this study is to find out if the diffusion tensor tractography technique can provide prognostic information regarding clinical outcome following ischemic stroke.

Subjects and methods

Forty patients with acute ischemic stroke were studied with DTI. Size of infraction, degree of reduction of fractional anisotropy (FA), and pattern of corticospinal tract (CST) affection were identified. We assessed our patients according to the National Institute of Health Stroke Scale (NIHSS) and Medical Research Council (MRC) scale at onset of stroke and 3 months later.

Results

FA reduction was correlated with MRC and NIHSS on admission (P < 0.001, 0.004 respectively) and after 3 months (P < 0.001, 0.013 respectively). The pattern of CST affection was associated with NIHSS and MRC after 3 months (P = 0.035, 0.001 respectively).

Conclusion

DTI may be an indirect indicator of the ischemic stroke outcome.

Characterization of tissue and functional deficits in a clinically translational pig model of acute ischemic stroke

The acute stroke phase is a critical time frame used to evaluate stroke severity, therapeutic options, and prognosis while also serving as a major tool for the development of diagnostics. To further understand stroke pathophysiology and to enhance the development of treatments, our group developed a translational pig ischemic stroke model. In this study, the evolution of acute ischemic tissue damage, immune responses, and functional deficits were further characterized. Stroke was induced by middle cerebral artery occlusion in Landrace pigs. At 24 h post-stroke, magnetic resonance imaging revealed a decrease in ipsilateral diffusivity, an increase in hemispheric swelling resulting in notable midline shift, and intracerebral hemorrhage. Stroke negatively impacted white matter integrity with decreased fractional anisotropy values in the internal capsule. Like patients, pigs showed a reduction in circulating lymphocytes and a surge in neutrophils and band cells. Functional responses corresponded with structural changes through reductions in open field exploration and impairments in spatiotemporal gait parameters. Characterization of acute ischemic stroke in pigs provided important insights into tissue and functional-level assessments that could be used to identify potential biomarkers and improve preclinical testing of novel therapeutics.

Evaluation of ischemic lesions after carotid artery stenting with diffusion-weighted imaging

BACKGROUND

Almost 90% of cerebral thromboembolism cases are caused by atherosclerosis. Craniocervical atherosclerosis is often observed at the carotid bifurcation and is responsible for 20%-30% of all stroke cases. The course of atherosclerotic carotid artery stenosis varies depending on the grade of stenosis and characteristics of the plaque. Carotid artery stenting (CAS) can be used as a less invasive method in patients with symptomatic and asymptomatic high-grade carotid artery stenosis. Diffusion-weighted imaging (DWI) is an effective method for detection of silent or symptomatic acute ischemic lesions that may arise due to CAS or carotid endarterectomy. The number and volume of new ischemic lesions are determined using DWI.

AIM

To evaluate the number and volume of ischemic lesions and their cerebral parenchymal and vascular distribution after CAS using DWI.

METHODS

Forty-seven male (73.4%) and seventeen female (26.6%) patients (total, n = 64) aged 42-84 years (mean 67.96 ± 8.03 years) diagnosed with carotid stenosis between October 2006 and July 2012 were included in this retrospective study. Twelve of the cases (18.8%) were asymptomatic, while fifty-two (81.2%) were symptomatic. The area where the stenosis was highest was measured, and the stenosis rate was determined using the North American Symptomatic Carotid Endarterectomy Trial method. DWI of the cases was evaluated by two radiologists experienced in neuroradiology (B.A. with more than 15 years of experience, E.G. with more than 10 years of experience). Routine DWI examinations were carried out by a 1.5 T MR device 1 h before and after the operation. Since the ischemic lesions that developed in the first hour and in the follow-up period of 5-24 h were assumed to be due to CAS, all lesions within the first 24 h were considered as new ischemias.

RESULTS

In the present study, 39 new ischemic lesions were detected in 20 cases. The average number of new lesions after all CAS operations was 0.62. They were mostly located in the occipital lobes, followed by the frontal and parietal lobes. These new ischemic lesions were most common in the middle cerebral artery territory, followed by the posterior cerebral artery territory and middle cerebral artery-posterior cerebral artery watershed areas. New lesions were found in 31.2% (20/64) of patients, including 17 (26.5%) in ipsilateral and three (4.6%) in contralateral hemispheres. New bilateral lesions were detected in one case (1.5%). The average volume of the new ischemic lesions detected by the two observers was 1.10 cm³. The numbers of newly appearing ischemic lesions in DWI after CAS were significantly higher in cases where stenting was applied on the left side of the carotid artery and in cases where longer plaques (> 1 cm) were responsible for the narrowing in symptomatic patients. The stenosis rate was low in the group with ulcerated plaques.

CONCLUSION

New ischemic lesions due to CAS appear mostly in the main arterial territory but they may also occur in watershed areas.

Association between white matter hyperintensities and stroke in a West African patient population: Evidence from the Stroke Investigative Research and Educational Network study

BACKGROUND

This study is part of the Stroke Investigative Research and Educational Network (SIREN), the largest study of stroke patients in Africa to date, with computed tomography (CT) or magnetic resonance (MR) imaging data for each patient to confirm stroke. Prior imaging studies performed using high-field MR (≥1.5T) have shown that white matter hyperintensities (WMH), signs of microangiopathy in the subcortical brain, are correlated with many stroke risk factors as well as poor stroke outcomes. The aim of this study was the evaluation of MR images (0.3T-1.5T) from the SIREN study to determine associations between WMH volumes in West African patients and both stroke outcomes and stroke risk factors identified in the SIREN study.

MATERIALS AND METHODS

Brain MR images of 130 Western African stroke patients (age ​= ​57.87 ​± ​14.22) were processed through Lesion Segmentation Toolbox of the Statistical Parametric Mapping software to extract all areas of hyperintensity in the brain. WMH was separated from stroke lesion hyperintensity and WMH volume was computed and summed. A stepwise linear regression and multivariate analysis was performed between patients' WMH volume and sociodemographic and clinical indices.

RESULTS

Multivariate analysis showed that high WMH volume was statistically significantly positively correlated with age (β ​= ​0.44, p ​= ​0.001), waist/hip ratio (β ​= ​0.22, p ​= ​0.03), and platelet count (β ​= ​0.19, p ​= ​0.04) after controlling for head size in a Western African stroke population.

CONCLUSION

Associations between WMH and age and waist/hip ratio previously identified in Western countries were demonstrated for the first time in a resource-limited, homogeneous black African community using low-field MR scanners.

Recanalization following Endovascular treatment and imaging of PErfusion, Regional inFarction and atrophy to Understand Stroke Evolution-NA1 (REPERFUSE-NA1)

RATIONALE

Following endovascular treatment, poor clinical outcomes are more frequent if the initial infarct core or volume of irreversible brain damage is large. Clinical outcomes may be improved using neuroprotective agents that reduce stroke volume and improve recovery.

AIM

The aim of the REPERFUSE NA1 was to replicate the preclinical neuroprotection study that significantly reduced infarct volume in a primate model of ischemia reperfusion. Specifically, REPERFUSE NA1 will determine if administration of the neuroprotectant NA1 prior to endovascular therapy can significantly reduce early (Day 2 subtract Day 1 diffusion-weighted imaging volume) and delayed secondary infarct (90-day whole brain atrophy plus FLAIR volume-Day 1 diffusion-weighted imaging volume) growth, as measured by magnetic resonance imaging.

METHODS AND DESIGN

REPERFUSE-NA1 is a magnetic resonance imaging observational substudy of ESCAPE-NA1 (ClinicalTrialGov NCT02930018). A total of 150 acute stroke patients will be recruited (including 20% attrition) that have been randomized to either NA1 or placebo in the ESCAPE-NA1 trial.

STUDY OUTCOMES

Primary-Early infarct growth measured using diffusion-weighted imaging will be at least 30% smaller in patients receiving NA1 compared to placebo. Secondary-Delayed secondary stroke injury at 90 days will be significantly reduced in patients receiving NA1 compared to placebo, as well as delayed secondary growth at 90 days.

CONCLUSION

REPERFUSE-NA1 will demonstrate the effect of NA1 neuroprotection on reducing the early and delayed stroke injury after reperfusion treatment.

Predicting Clinical Outcome of Stroke Patients with Tractographic Feature

The volume of stroke lesion is the gold standard for predicting the clinical outcome of stroke patients. However, the presence of stroke lesion may cause neural disruptions to other brain regions, and these potentially damaged regions may affect the clinical outcome of stroke patients. In this paper, we introduce the tractographic feature to capture these potentially damaged regions and predict the modified Rankin Scale (mRS), which is a widely used outcome measure in stroke clinical trials. The tractographic feature is built from the stroke lesion and average connectome information from a group of normal subjects. The tractographic feature takes into account different functional regions that may be affected by the stroke, thus complementing the commonly used stroke volume features. The proposed tractographic feature is tested on a public stroke benchmark Ischemic Stroke Lesion Segmentation 2017 and achieves higher accuracy than the stroke volume and the state-of-the-art feature on predicting the mRS grades of stroke patients. Also, the tractographic feature yields a lower average absolute error than the commonly used stroke volume feature.

Cortical gamma-synchrony measured with magnetoencephalography is a marker of clinical status and predicts clinical outcome in stroke survivors

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The outcome of stroke survivors is difficult to anticipate.

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Gamma synchrony is a reliable measure of brain function and reserve.

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Gamma synchrony is measured with MEG in stroke survivors undergoing rehab.

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Auditory-entrained gamma synchrony correlates with clinical status and outcome.

Background

The outcome of stroke survivors is difficult to anticipate. While the extent of the anatomical brain lesion is only poorly correlated with the prognosis, functional measures of cortical synchrony, brain networks and cortical plasticity seem to be good predictors of clinical recovery. In this field, gamma (>30 Hz) cortical synchrony is an ideal marker of brain function, as it plays a crucial role for the integration of information, it is an indirect marker of Glutamate/GABA balance and it directly estimates the reserve of parvalbulin-positive neurons, key players in synaptic plasticity. In this study we measured gamma synchronization driven by external auditory stimulation with magnetoencephalography and tested whether it was predictive of the clinical outcome in stroke survivors undergoing intensive rehabilitation in a tertiary rehabilitation center.

Material and methods

Eleven stroke survivors undergoing intensive rehabilitation were prospectively recruited. Gamma synchrony was measured non-invasively within one month from stroke onset with magnetoencephalography, both at rest and during entrainment with external 40 Hz amplitude modulated binaural sounds. Lesion location and volume were quantitatively assessed through a high-resolution anatomical MRI. Barthel index (BI) and Functional Independence Measure (FIM) scales were measured at the beginning and at the end of the admission to the rehabilitation unit.

Results

The spatial distribution of cortical gamma synchrony was altered, and the physiological right hemispheric dominance observed in healthy controls was attenuated or lost. Entrained gamma synchronization (but not resting state gamma synchrony) showed a very high correlation with the clinical status at both admission and discharge (both BI and FIM). Neither clinical status nor gamma synchrony showed a correlation with lesion volume.

Conclusions

Cortical gamma synchrony related to auditory entrainment can be reliably measured in stroke patients. Gamma synchrony is strongly associated with the clinical outcome of stroke survivors undergoing rehabilitation.

Cognitive and Academic Outcomes Following Childhood Cortical Stroke

The majority of pediatric neuropsychological stroke research has focused on perinatal stroke outcomes given its relative frequency. Meanwhile, childhood-onset stroke is under-represented in the literature, resulting in limited knowledge about its neurocognitive sequelae. This retrospective study examined cognitive outcomes in children and youth (n = 27) with childhood arterial ischemic stroke (stroke occurring between 29 days and 18 years of life) isolated to the cortical region. Intellectual, academic, language, visual-perception, visual-motor integration, fine motor coordination, and executive function scores were examined relative to normative means. Results indicate that although these children are doing well in terms of general intellectual ability, they demonstrate lower scores on tasks of processing speed and fine motor coordination. Exploratory analysis also revealed that of the personal and neurologic factors examined, age at stroke was positively correlated with perceptual reasoning and fine motor control, age at assessment was negatively correlated with math calculation abilities, and maternal education was positively correlated with working memory and parent-reported behavioral regulation and impulse inhibition abilities. While neurologic variables were not predictive of cognitive neuropsychological outcomes, those with significant poorer performance had higher rates of medium/large, right-sided lesions with frontal lobe involvement. Our results highlight the overall resilience of the injured developing brain but also the vulnerability of specific cognitive skills within this unique population.

The role of advanced neuroimaging techniques in ischemic stroke prevention

In great part due to recent advances in medical technology, ischemic cerebral stroke has become an increasingly treatable condition, which requires urgent measures and which rely on pharmacological and/or interventional measures. Due to its high prevalence, preventive measures should also be undertaken, and this is a situation where the use of advanced neuroimaging techniques could be helpful in certain underlying diseases. What is proposed here is to discuss how modern neuroimaging techniques (advanced magnetic resonance (MR) techniques and/or nuclear medicine techniques such as positron emission tomography (PET)) could help in situations that would otherwise lead to a stroke. Since both primary and secondary prevention measures are often required, we see that the techniques can be helpful in both situations. The diseases that cause stroke that can be investigated are, among others, carotid stenosis; transient ischemic attacks (TIAs) may also be followed by a major stroke if nothing is undertaken. It has been established that carotid stenosis is to be treated in the presence of a significant lesion that has neurological symptoms. The question of how to deal with these patients often arises when the relationship between the stenosis and symptoms is not significant or the symptomatology unclear. In such situations, either PET and/or fat-saturated T1 images of the carotids can help to demonstrate the embolic nature of the plaque. We have seen that carotid plaque vulnerability, which can cause embolism, can be associated with plaque inflammation (seen on PET) or plaque haemorrhage (seen on MR images). Also, while PET and MRI will demonstrate different stages of plaque vulnerability, they can both help to demonstrate vascular lesions that are at risk of causing significant ischemic events. Diffusion-weighted imaging (DWI) has shown that some TIAs may indeed be ischemic brain lesions with a transient symptomatology. The early use of DWI can thus help treat these patients more acutely. Based on this, we have seen that newer imaging techniques can provide additional knowledge about conditions that may lead to stroke and be treated. This should have a major impact on patient outcomes and ultimately on healthcare costs related to this condition.

Rich-Club Organization: An Important Determinant of Functional Outcome After Acute Ischemic Stroke

Objective: To determine whether the rich-club organization, essential for information transport in the human connectome, is an important biomarker of functional outcome after acute ischemic stroke (AIS). Methods: Consecutive AIS patients (N = 344) with acute brain magnetic resonance imaging (MRI) (<48 h) were eligible for this study. Each patient underwent a clinical MRI protocol, which included diffusion weighted imaging (DWI). All DWIs were registered to a template on which rich-club regions have been defined. Using manual outlines of stroke lesions, we automatically counted the number of affected rich-club regions and assessed its effect on the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS; obtained at 90 days post-stroke) scores through ordinal regression. Results: Of 344 patients (median age 65, inter-quartile range 54-76 years) with a median DWI lesion volume (DWIv) of 3cc, 64% were male. We established that an increase in number of rich-club regions affected by a stroke increases the odds of poor stroke outcome, measured by NIHSS (OR: 1.77, 95%CI 1.41-2.21) and mRS (OR: 1.38, 95%CI 1.11-1.73). Additionally, we demonstrated that the OR exceeds traditional markers, such as DWIv (OR_NIHSS 1.08, 95%CI 1.06-1.11; OR_mRS 1.05, 95%CI 1.03-1.07) and age (OR_NIHSS 1.03, 95%CI 1.01-1.05; OR_mRS 1.05, 95%CI 1.03-1.07). Conclusion: In this proof-of-concept study, the number of rich-club nodes affected by a stroke lesion presents a translational biomarker of stroke outcome, which can be readily assessed using standard clinical AIS imaging protocols and considered in functional outcome prediction models beyond traditional factors.

Sex-specific differences in white matter microvascular integrity after ischaemic stroke

Background and purpose

Functional outcomes after ischaemic stroke are worse in women, despite adjusting for differences in comorbidities and treatment approaches. White matter microvascular integrity represents one risk factor for poor long-term functional outcomes after ischaemic stroke. The aim of the study is to characterise sex-specific differences in microvascular integrity in individuals with acute ischaemic stroke.

Methods

A retrospective analysis of subjects with acute ischaemic stroke and brain MRI with diffusion-weighted (DWI) and dynamic-susceptibility contrast-enhanced (DSC) perfusion-weighted imaging obtained within 9 hours of last known well was performed. In the hemisphere contralateral to the acute infarct, normal-appearing white matter (NAWM) microvascular integrity was measured using the K₂ coefficient and apparent diffusion coefficient (ADC) values. Regression analyses for predictors of K₂ coefficient, DWI volume and good outcome (90-day modified Rankin scale (mRS) score <2) were performed.

Results

105 men and 79 women met inclusion criteria for analysis. Despite no difference in age, women had increased NAWM K₂ coefficient (1027.4 vs 692.7×10^–6/s; p=0.006). In women, atrial fibrillation (β=583.6; p=0.04) and increasing NAWM ADC (β=4.4; p=0.02) were associated with increased NAWM K₂ coefficient. In multivariable regression analysis, the K₂ coefficient was an independent predictor of DWI volume in women (β=0.007; p=0.01) but not men.

Conclusions

In women with acute ischaemic stroke, increased NAWM K₂ coefficient is associated with increased infarct volume and chronic white matter structural integrity. Prospective studies investigating sex-specific differences in white matter microvascular integrity are needed.

Individualized quantification of the benefit from reperfusion therapy using stroke predictive models

PURPOSE

Recent imaging developments have shown the potential of voxel-based models in assessing infarct growth after stroke. Many models have been proposed but their relevance in predicting the benefit of a reperfusion therapy remains unclear. We searched for a predictive model whose volumetric predictions would identify stroke patients who are to benefit from tissue plasminogen activator (t-PA)-induced reperfusion.

MATERIAL AND METHODS

Forty-five cases were used to study retrospectively stroke progression from admission to end of follow-up. Predictive approaches based on various statistical models, predictive variables and spatial filtering methods were compared. The optimal approach was chosen according to the area under the precision-recall curve (AUPRC). The final lesion volume was then predicted assuming that the patient would or would not reperfuse. Patients, with an acute lesion of ≤50 ml and a predicted reduction in the presence of reperfusion >6 ml and >25% of the acute lesion, were classified as responders.

RESULTS

The optimal model was a logistic regression using the voxel distance to the acute lesion, the volume of the acute lesion and Gaussian-filtered MRI contrast parameters as predictive variables. The predictions gave a median AUPRC of 0.655, a median AUC of 0.976 and a median volumetric error of 8.29 ml. Nineteen patients matched the responder profile. A non-significant trend of improved reduction in NIHSS score (-42.8%, p = .09) and in lesion volume (-78.1%, p = 0.21) following reperfusion was observed for responder patients.

CONCLUSION

Despite limited volumetric accuracy, predictive stroke models can be used to quantify the benefit of reperfusion therapies.

Lesion locations associated with persistent proprioceptive impairment in the upper limbs after stroke

Proprioceptive deficits are common after stroke and have been associated with poorer recovery. Relatively little is known about the brain regions beyond primary somatosensory cortex that contribute to the percept of proprioception in humans. We examined a large sample (n = 153) of stroke survivors longitudinally to determine which brain regions were associated with persistent post-stroke proprioceptive deficits. A robotic exoskeleton quantified two components of proprioception, position sense and kinesthesia (movement sense), at 2 weeks and again at 6 months post-stroke. A statistical region of interest (sROI) analysis compared the lesion-behaviour relationships of those subjects with cortical and subcortical stroke (n = 136). The impact of damage to brainstem and cerebellum (n = 17) was examined separately. Results indicate that damage to the supramarginal gyrus, the arcuate fasciculus, and Heschl's gyrus are associated with deficits in position sense and kinesthesia at 6 months post-stroke. These results suggest that regions beyond the primary somatosensory cortex contribute to our sense of limb position and movement. This information extends our understanding of proprioceptive processing and may inform personalized interventions such as non-invasive brain stimulation where specific brain regions can be targeted to potentially improve stroke recovery.

Relation of white matter hyperintensities and motor deficits in chronic stroke

BACKGROUND

Infarct size and location account for only a relatively small portion of post-stroke motor impairment, suggesting that other less obvious factors may be involved.

OBJECTIVE

Examine the relationship between white matter hyperintensity (WMH) load among other factors and upper extremity motor deficit in patients with mild to moderate chronic stroke.

METHODS

The magnetic resonance images of 28 patients were studied. WMH load was assessed as total WMH volume and WMH overlap with the corticospinal tract in the centrum semiovale. Hemiparetic arm function was measured using the Motor Activity Log (MAL) and Wolf Motor Function Test (WMFT).

RESULTS

Hierarchical multiple regression models found WMH volume predicted motor deficits in both real-world arm use (MAL;ΔR2 = 0.12, F(1, 22) = 4.73, p = 0.04) and in arm motor capacity as measured by a laboratory motor function test (WMFT;ΔR2 = 0.18, F(1, 22) = 6.32, p = 0.02) over and above age and lesion characteristics. However, these models accounted for less than half of the variance in post-stroke motor deficits.

CONCLUSION

The results suggest that WMH may be an important factor to consider in stroke-related upper extremity motor impairment. Nonetheless, the basis of the largest part of the post-stroke motor deficit remains unaccounted for by structural CNS factors. This component may be behavioral or learned, involving learned nonuse.

New developments in clinical ischemic stroke prevention and treatment and their imaging implications

Acute ischemic stroke results from blockage of a cerebral artery or impaired cerebral blood flow due to cervical or intracranial arterial stenosis. Ischemic stroke prevention seeks to minimize the risk of developing impaired cerebral perfusion by controlling vascular and cardiac disease risk factors. Similarly, ischemic stroke treatment aims to restore cerebral blood flow through recanalization of an occluded artery or dilation of a severely narrowed artery that supplies cerebral tissue. Stroke prevention and treatment are increasingly informed by imaging studies, and neurovascular and cerebral perfusion imaging has become essential in in guiding ischemic stroke prevention and treatment. Here we review the latest advances in ischemic stroke prevention and treatment with an emphasis on the neuroimaging principles emphasized in recent randomized trials. Future research directions that should be explored in ischemic stroke prevention and treatment are also discussed.

Time-dependent decline of body-specific attention to the paretic limb in chronic stroke patients

OBJECTIVE

To examine whether reduced body-specific attention to a paretic limb is found in chronic stroke patients in a time-dependent manner.

METHODS

Twenty-one patients with chronic hemiparesis (10 left and 11 right hemiparesis) after subcortical stroke and 18 age-matched healthy controls were recruited in this study. Standard neuropsychological examinations showed no clear evidence of spatial neglect in any patient. In order to quantitatively measure spatial attention to the paretic hand, a visual detection task for detecting a target appearing on the surface of either a paretic or dummy hand was used. This task can measure the body facilitation effect, which makes faster detection of a target on the body compared with one far from the body.

RESULTS

In stroke patients, there was no difference in the reaction time for a visual target between the paretic and the dummy hands, while the healthy participants showed faster detection for the visual target on the real hand than on the dummy one. The index of the body facilitation effect, subtracting the reaction time for the target-on-paretic hand from that for the target-on-dummy one, was correlated with the duration since onset and with finger function test on the Stroke Impairment Assessment Set.

CONCLUSIONS

The reduction of the body facilitation effect in the paretic limb suggests the decline of body-specific attention to the paretic one in patients with chronic hemiparesis. This decline of body-specific attention, leading to neglect for the paretic limb, will be one of the most serious problems for rehabilitation based on use-dependent plasticity.

Ischemic Volume and Neurological Deficit: Correlation of Computed Tomography Perfusion with the National Institutes of Health Stroke Scale Score in Acute Ischemic Stroke

BACKGROUND

The National Institutes of Health Stroke Scale (NIHSS) is the most adopted stroke patients' evaluation tool in emergency settings to assess the severity of stroke and to determine the patients' eligibility for specific treatments. Computed tomography perfusion (CTP) is crucial to identify salvageable tissue that can benefit from the reperfusion treatment. The aim of this study is to identify the relation between the NIHSS scores and the hypoperfused volumes evaluated by CTP in patients with hyperacute ischemic stroke.

METHODS

This retrospective study was conducted on 105 patients with ischemic stroke who underwent NIHSS assessment and CTP in the hyperacute phase. Hypoperfused volume was evaluated by CTP maps processed with semi-automatic algorithm. An analysis was conducted to determine the degree of correlation between the NIHSS scores and the ischemic lesion volumes and to investigate the relation between the anterior and the posterior circulation strokes, as well as between the right and the left hemispheric strokes.

RESULTS

A significant correlation was found between ischemic volume and NIHSS score at baseline (r = .82; P < .0001) in the entire cohort. A high NIHSS-volume correlation was identified in the anterior circulation stroke (r = .76; P < .0001); whereas, it was nonsignificant in the posterior circulation stroke. NIHSS score and volume correlated for the left and the right hemispheric strokes (r = .83 and .81; P < .0001), showing a slightly higher slope in the left.

CONCLUSION

This study showed a strong correlation between the baseline NIHSS score and the ischemic volume estimated by CTP. We confirmed that NIHSS is a reliable predictor of perfusion deficits in acute ischemic stroke. CTP allows fast imaging assessment in the hyperacute phase. The results highlight the importance of these diagnostic tools in the assessment of stroke severity and in acute decision-making.

Cerebral Metastases of Lung Cancer Mimicking Multiple Ischaemic Lesions - A Case Report and Review of Literature

Background

Restricted diffusion that is found on magnetic resonance diffusion-weighted imaging (DWI) typically indicates acute ischaemic stroke. However, restricted diffusion can also occur in other diseases, like metastatic brain tumours, which we describe in this case report.

Case Report

A 57-year-old male, with a diagnosis of small-cell cancer of the right lung (microcellular anaplastic carcinoma), was admitted with focal neurological symptoms. Initial brain MRI revealed multiple, disseminated lesions that were hyperintense on T2-weighted images and did not enhance after contrast administration; notably, some lesions manifested restricted diffusion on DWI images. Based on these findings, disseminated ischaemic lesions were diagnosed. On follow-up MRI that was performed after 2 weeks, we observed enlargement of the lesions; there were multiple, disseminated, sharply outlined, contrast-enhancing, oval foci with persistent restriction of diffusion. We diagnosed the lesions as disseminated brain metastases due to lung cancer. To our knowledge, this is the first description of a patient with brain metastases that were characterised by restricted diffusion and no contrast enhancement.

Conclusions

Multiple, disseminated brain lesions, that are characterised by restricted diffusion on DWI, typically indicate acute or hyperacute ischemic infarcts; however, they can also be due to hypercellular metastases, even if no contrast enhancement is observed. This latter possibility should be considered particularly in patients with cancer.

Human Neural Stem Cell Extracellular Vesicles Improve Recovery in a Porcine Model of Ischemic Stroke

BACKGROUND AND PURPOSE

Recent work from our group suggests that human neural stem cell-derived extracellular vesicle (NSC EV) treatment improves both tissue and sensorimotor function in a preclinical thromboembolic mouse model of stroke. In this study, NSC EVs were evaluated in a pig ischemic stroke model, where clinically relevant end points were used to assess recovery in a more translational large animal model.

METHODS

Ischemic stroke was induced by permanent middle cerebral artery occlusion (MCAO), and either NSC EV or PBS treatment was administered intravenously at 2, 14, and 24 hours post-MCAO. NSC EV effects on tissue level recovery were evaluated via magnetic resonance imaging at 1 and 84 days post-MCAO. Effects on functional recovery were also assessed through longitudinal behavior and gait analysis testing.

RESULTS

NSC EV treatment was neuroprotective and led to significant improvements at the tissue and functional levels in stroked pigs. NSC EV treatment eliminated intracranial hemorrhage in ischemic lesions in NSC EV pigs (0 of 7) versus control pigs (7 of 8). NSC EV-treated pigs exhibited a significant decrease in cerebral lesion volume and decreased brain swelling relative to control pigs 1-day post-MCAO. NSC EVs significantly reduced edema in treated pigs relative to control pigs, as assessed by improved diffusivity through apparent diffusion coefficient maps. NSC EVs preserved white matter integrity with increased corpus callosum fractional anisotropy values 84 days post-MCAO. Behavior and mobility improvements paralleled structural changes as NSC EV-treated pigs exhibited improved outcomes, including increased exploratory behavior and faster restoration of spatiotemporal gait parameters.

CONCLUSIONS

This study demonstrated for the first time that in a large animal model novel NSC EVs significantly improved neural tissue preservation and functional levels post-MCAO, suggesting NSC EVs may be a paradigm changing stroke therapeutic.

Human Neural Stem Cell Extracellular Vesicles Improve Tissue and Functional Recovery in the Murine Thromboembolic Stroke Model

Over 700 drugs have failed in stroke clinical trials, an unprecedented rate thought to be attributed in part to limited and isolated testing often solely in “young” rodent models and focusing on a single secondary injury mechanism. Here, extracellular vesicles (EVs), nanometer-sized cell signaling particles, were tested in a mouse thromboembolic (TE) stroke model. Neural stem cell (NSC) and mesenchymal stem cell (MSC) EVs derived from the same pluripotent stem cell (PSC) line were evaluated for changes in infarct volume as well as sensorimotor function. NSC EVs improved cellular, tissue, and functional outcomes in middle-aged rodents, whereas MSC EVs were less effective. Acute differences in lesion volume following NSC EV treatment were corroborated by MRI in 18-month-old aged rodents. NSC EV treatment has a positive effect on motor function in the aged rodent as indicated by beam walk, instances of foot faults, and strength evaluated by hanging wire test. Increased time with a novel object also indicated that NSC EVs improved episodic memory formation in the rodent. The therapeutic effect of NSC EVs appears to be mediated by altering the systemic immune response. These data strongly support further preclinical development of a NSC EV-based stroke therapy and warrant their testing in combination with FDA-approved stroke therapies.

White matter hyperintensity and stroke lesion segmentation and differentiation using convolutional neural networks

White matter hyperintensities (WMH) are a feature of sporadic small vessel disease also frequently observed in magnetic resonance images (MRI) of healthy elderly subjects. The accurate assessment of WMH burden is of crucial importance for epidemiological studies to determine association between WMHs, cognitive and clinical data; their causes, and the effects of new treatments in randomized trials. The manual delineation of WMHs is a very tedious, costly and time consuming process, that needs to be carried out by an expert annotator (e.g. a trained image analyst or radiologist). The problem of WMH delineation is further complicated by the fact that other pathological features (i.e. stroke lesions) often also appear as hyperintense regions. Recently, several automated methods aiming to tackle the challenges of WMH segmentation have been proposed. Most of these methods have been specifically developed to segment WMH in MRI but cannot differentiate between WMHs and strokes. Other methods, capable of distinguishing between different pathologies in brain MRI, are not designed with simultaneous WMH and stroke segmentation in mind. Therefore, a task specific, reliable, fully automated method that can segment and differentiate between these two pathological manifestations on MRI has not yet been fully identified. In this work we propose to use a convolutional neural network (CNN) that is able to segment hyperintensities and differentiate between WMHs and stroke lesions. Specifically, we aim to distinguish between WMH pathologies from those caused by stroke lesions due to either cortical, large or small subcortical infarcts. The proposed fully convolutional CNN architecture, called uResNet, that comprised an analysis path, that gradually learns low and high level features, followed by a synthesis path, that gradually combines and up-samples the low and high level features into a class likelihood semantic segmentation. Quantitatively, the proposed CNN architecture is shown to outperform other well established and state-of-the-art algorithms in terms of overlap with manual expert annotations. Clinically, the extracted WMH volumes were found to correlate better with the Fazekas visual rating score than competing methods or the expert-annotated volumes. Additionally, a comparison of the associations found between clinical risk-factors and the WMH volumes generated by the proposed method, was found to be in line with the associations found with the expert-annotated volumes.

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Robust, fully automatic white matter hyperintensity and stroke lesion segmentation and differentiation

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A novel patch sampling strategy used during CNN training that avoids the introduction of erroneous locality assumptions

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Improved segmentation accuracy in terms of Dice scores when compared to well established state-of-the-art methods

The Association between Diffusion MRI-Defined Infarct Volume and NIHSS Score in Patients with Minor Acute Stroke

BACKGROUND

Prior studies have shown a correlation between the National Institutes of Health Stroke Scale (NIHSS) and stroke volume on diffusion weighted imaging (DWI); data are more limited in patients with minor stroke. We sought to determine the association between DWI lesion(s) volume and the (1) total NIHSS score and (2) NIHSS component scores in patients with minor stroke.

METHODS

We included all patients with minor stroke (NIHSS 0-5) enrolled in the Stroke Warning Information and Faster Treatment study. We calculated lesion(s) volume (cm³ ) on the DWI sequence using Medical Image Processing, Analysis, and Visualization (MIPAV, NIH, Version 7.1.1). We used nonparametric tests to study the association between the primary outcome, DWI lesion(s) volume, and the predictors (NIHSS score and its components).

RESULTS

We identified 894 patients with a discharge diagnosis of minor stroke; 709 underwent magnetic resonance imaging and 510 were DWI positive. There was a graded relationship between the NIHSS score and median DWI lesion volume in cm³ : (NIHSS 0: 7.1, NIHSS 1: 8.0, NIHSS 2: 17.1, NIHSS 3: 11.6, NIHSS 4: 19.0, and NIHSS 5: 23.6, P < .01). The median lesion volume was significantly higher in patients with neglect (105.6 vs. 12.5, P = .025), language disorder (34.6 vs. 11.9, P < .001), and visual field impairment (185.6 vs. 11.6, P < .001). Other components of the NIHSS were not associated with lesion volume.

CONCLUSION

In patients with minor stroke, the nature of deficit when used with the NIHSS score can improve prediction of infarct volume. This may have clinical and therapeutic implications.

Axillary versus innominate artery cannulation for antegrade cerebral perfusion in aortic surgery: design of the Aortic Surgery Cerebral Protection Evaluation (ACE) CardioLink-3 randomised trial

INTRODUCTION

Neurological injury remains the major cause of morbidity and mortality following open aortic arch repair. Systemic hypothermia along with antegrade cerebral perfusion (ACP) is the accepted cerebral protection approach, with axillary artery cannulation being the most common technique used to establish ACP. More recently, innominate artery cannulation has been shown to be a safe and efficacious method for establishing ACP. Inasmuch as there is a lack of high-quality data comparing axillary and innominate artery ACP, we have designed a randomised, multi-centre clinical trial to compare both cerebral perfusion strategies with regards to brain morphological injury using diffusion-weighted MRI (DW-MRI).

METHODS AND ANALYSIS

110 patients undergoing elective aortic surgery with repair of the proximal arch requiring an open distal anastamosis will be randomised to either the innominate artery or the axillary artery cannulation strategy for establishing unilateral ACP during systemic circulatory arrest with moderate levels of hypothermia. The primary safety endpoint of this trial is the proportion of patients with new radiologically significant ischaemic lesions found on postoperative DW-MRI compared with preoperative DW-MRI. The primary efficacy endpoint of this trial is the difference in total operative time between the innominate artery and the axillary artery cannulation group.

ETHICS AND DISSEMINATION

The study protocol and consent forms have been approved by the participating local research ethics boards. Publication of the study results is anticipated in 2018 or 2019. If this study shows that the innominate artery cannulation technique is non-inferior to the axillary artery cannulation technique with regards to brain morphological injury, it will establish the innominate artery cannulation technique as a safe and potentially more efficient method of antegrade cerebral perfusion in aortic surgery.

TRIAL REGISTRATION NUMBER

NCT02554032.

Predicting Domain-Specific Health-Related Quality of Life Using Acute Infarct Volume

BACKGROUND AND PURPOSE

Limited data exist on the relationship between acute infarct volume and health-related quality of life (HRQOL) measures after ischemic stroke. We evaluated whether acute infarct volume predicts domain-specific Neuro-Quality of Life scores at 3 months after stroke.

METHODS

Between 2012 and 2014, we prospectively enrolled consecutive patients with ischemic stroke and calculated infarct volume. Outcome scores at 3 months included modified Rankin Scale and Neuro-Quality of Life T scores. We evaluated whether volume organized by quartiles predicted modified Rankin Scale and HRQOL scores at 3 months using logistic and linear regression as appropriate, adjusting for relevant covariates. We calculated variance accounted for (R²) overall and by volume for each domain of HRQOL.

RESULTS

Among 490 patients (mean age 64.2±15.86 years; 51.2% male; 63.3% White) included for analysis, 58 (11.8%) were disabled (modified Rankin Scale score of >2) at 3 months. In unadjusted analysis, the highest volume quartile remained a significant predictor of 1 HRQOL domain, applied cognition-general concerns (R²=0.06; P<0.001). Our fully adjusted prediction model explained 32% to 51% of the variance in HRQOL: upper extremity (R²=0.32), lower extremity (R²=0.51), executive function (R²=0.45), and general concerns (R²=0.34).

CONCLUSIONS

Acute infarct volume is a poor predictor of HRQOL domains after ischemic stroke, with the exception of the cognitive domain. Overall, clinical and imaging variables explained <50% of the variance in HRQOL outcomes at 3 months. Our data imply that a broad range of factors, some known and others undiscovered, may better predict poststroke HRQOL than what is currently available.

Behavioural clusters and predictors of performance during recovery from stroke

We examined the patterns and variability of recovery post-stroke in multiple behavioral domains. A large cohort of first time stroke patients with heterogeneous lesions was studied prospectively and longitudinally at 1-2 weeks, 3 months and one year post-injury with structural MRI to measure lesion anatomy and in-depth neuropsychological assessment. Impairment was described at all timepoints by a few clusters of correlated deficits. The time course and magnitude of recovery was similar across domains, with change scores largely proportional to the initial deficit and most recovery occurring within the first three months. Damage to specific white matter tracts produced poorer recovery over several domains: attention and superior longitudinal fasciculus II/III, language and posterior arcuate fasciculus, motor and corticospinal tract. Finally, after accounting for the severity of the initial deficit, language and visual memory recovery/outcome was worse with lower education, while the occurrence of multiple deficits negatively impacted attention recovery.

White matter injury induced by diabetes in acute stroke is clinically relevant: A preliminary study

The importance of white matter injury induced by diabetes in stroke severity and prognosis is largely unknown. We aimed to investigate the relationship between diabetes-related white matter injury beyond stroke lesions with acute neurological deficits and clinical outcome after stroke. In total, 36 stroke patients within 3-7 days after onset were enrolled. Neurological deficits on admission were assessed by National Institute of Health Stroke Score, and poor outcome at 3 months was defined as modified Rankin score >2. White matter tracts were compared between patients with diabetic and non-diabetic stroke using fractional anisotropy from diffusion tensor imaging. Regional white matter abnormality with decreased fractional anisotropy was observed in diabetic patients (n = 18) when compared to non-diabetic patients (n = 18). Decreased fractional anisotropy in ipsilesional distal corticospinal tract was independently associated with higher National Institute of Health Stroke Score motor component score (β = -0.444, p = 0.005), and decreased fractional anisotropy in contralesional superior longitudinal fasciculus I was independently related to poor outcome (odds ratio, 0.900; p = 0.033). Our findings suggested that only white matter injury induced by diabetes in specific tracts like corticospinal tract and superior longitudinal fasciculus beyond stroke lesions has clinically relevant, providing insight into the mechanism of stroke recovery under the diabetic condition.

Distinct inflammatory responses differentiate cerebral infarct from transient ischaemic attack

We previously reported on a 26-year-old patient who presented early during a large and eventually fatal cerebral infarct. Microarray analysis of blood samples from this patient demonstrated initially up-regulated and subsequently down-regulated Granzyme B (GzmB) expression, along with progressive up-regulation of genes for S100 calcium binding protein A12 (S100A12) and matrix metalloproteinase 9 (MMP-9). To confirm these findings, we investigated these parameters in patients with suspected stroke presenting within 6h of symptom onset to a single centre. Blood samples were taken at enrolment, then 1h, 3h and 24h post-enrolment for the examination of cellular, protein and genetic changes. Patients with subsequently confirmed ischaemic (n=18) or haemorrhagic stroke (n=11) showed increased intracellular concentrations of GzmB in all cell populations investigated (CD8⁺, CD8^- and Natural Killer [NK] cells). Infarct patients, however, demonstrated significantly reduced GzmB gene expression and increased circulating MMP-9 and S100A12 levels in contrast to transient ischaemic attack (TIA) patients or healthy controls. Furthermore, a pronounced neutrophilia was noted in the infarct and haemorrhage groups, while TIA patients (n=9) reflected healthy controls (n=10). These findings suggest a spectrum of immune response during stroke. TIA showed few immunological changes in comparison to infarct and haemorrhage, which demonstrated inhibition of GzmB production and a rise in neutrophil numbers and neutrophil-associated mediators. This implies a greater role of the innate immune system. These markers may provide novel targets for inhibition and reduction of secondary injury.