The relevance of rich club regions for functional outcome post-stroke is enhanced in women.

This study aimed to investigate the influence of stroke lesions in predefined highly interconnected (rich-club) brain regions on functional outcome post-stroke, determine their spatial specificity and explore the effects of biological sex on their relevance. We analyzed MRI data recorded at index stroke and ~3-months modified Rankin Scale (mRS) data from patients with acute ischemic stroke enrolled in the multisite MRI-GENIE study. Spatially normalized structural stroke lesions were parcellated into 108 atlas-defined bilateral (sub)cortical brain regions. Unfavorable outcome (mRS > 2) was modeled in a Bayesian logistic regression framework. Effects of individual brain regions were captured as two compound effects for (i) six bilateral rich club and (ii) all further non-rich club regions. In spatial specificity analyses, we randomized the split into "rich club" and "non-rich club" regions and compared the effect of the actual rich club regions to the distribution of effects from 1000 combinations of six random regions. In sex-specific analyses, we introduced an additional hierarchical level in our model structure to compare male and female-specific rich club effects. A total of 822 patients (age: 64.7[15.0], 39% women) were analyzed. Rich club regions had substantial relevance in explaining unfavorable functional outcome (mean of posterior distribution: 0.08, area under the curve: 0.8). In particular, the rich club-combination had a higher relevance than 98.4% of random constellations. Rich club regions were substantially more important in explaining long-term outcome in women than in men. All in all, lesions in rich club regions were associated with increased odds of unfavorable outcome. These effects were spatially specific and more pronounced in women.

Longitudinal Study Reveals Long-Term Proinflammatory Proteomic Signature After Ischemic Stroke Across Subtypes.

BACKGROUND: Inflammation contributes both to the pathogenesis of stroke and the response to brain injury. We aimed to identify proteins reflecting the acute-phase response and proteins more likely to reflect proinflammatory processes present before stroke by broadly profiling inflammation-related plasma proteins in a longitudinal ischemic stroke study. METHODS: Participants were from a Swedish ischemic stroke cohort (SAHLSIS [Sahlgrenska Academy Study on Ischemic Stroke], n=600 cases and n=600 controls). Plasma levels of 65 proteins including chemokines, interleukins, surface molecules, and immune receptors were measured once in controls and at 3× in cases: during the acute phase, after 3 months, and for a subgroup (n=223) at 7-year follow-up. Associations between proteins and ischemic stroke or subtype were investigated in multivariable binary regression models corrected for age, sex, vascular risk factors, and multiple testing. RESULTS: In the acute phase, 48 proteins were significantly and independently associated with ischemic stroke (false discovery rate adjusted P<0.05). At 3-month follow-up, 51 proteins and at 7-year follow-up 50 proteins were associated with ischemic stroke. The majority of proteins were upregulated in cases compared with controls (n=34 at all time points) and the most upregulated were CXCL5 (CXC chemokine ligand 5) and OSM (oncostatin M). Generally, large artery and cardioembolic stroke had the highest protein levels. However, several interesting subtype-specific differences were also detected at each time point. CONCLUSIONS: We found inflammation-related proteins that were differentially regulated in ischemic stroke cases compared with controls only in the acute phase and others that remained elevated also at later time points. This latter group of proteins could reflect underlying pathophysiological processes of relevance. Future studies both in terms of disease risk and prognostication are warranted.

Fatigue 7 years post-stroke: Predictors and correlated features.

BACKGROUND: Post-stroke fatigue (PSF) is common with great impact on quality of life. We explored predictive and cross-sectionally correlated features in the long term after ischemic stroke. METHODS: This study comprises 430 participants of the prospective Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), aged 18-69 years at index stroke. Information on acute stroke severity and cardiovascular risk factors was collected at index stroke. After 7 years, PSF was assessed by the Daily Fatigue Impact Scale (D-FIS). Cognitive, neurological, and functional outcomes, and symptoms of depression and anxiety, pain, insomnia, and physical activity were also assessed. Associations between baseline variables and PSF were analyzed by ordinal regression. Correlations between PSF and cross-sectionally assessed variables, and between PSF and baseline variables, were analyzed with Spearman's or point-biserial correlation for the whole sample and in sex-stratified analyses. RESULTS: At 7 years post-stroke, 80% of the participants reported some impact of fatigue. Female sex and stroke severity were independently associated with PSF, whereas no associations were detected with baseline cardiovascular risk factors. In cross-sectional analyses at 7 years, we found correlations between PSF and poor functional, neurological, and cognitive outcomes, as well as depressive symptoms, anxiety, insomnia, pain, and low physical activity (p < .001 throughout). The correlation with insomnia was stronger in women than in men (two-way ANOVA interaction test, p = .03). CONCLUSIONS: Our findings confirm that PSF is common in the long term after ischemic stroke and show a complex interplay with sex and several other outcomes. Future studies should address causal relationships and interventions towards fatigue and coexisting features.

Cognitive function is an important determinant of employment amongst young ischaemic stroke survivors with good physical recovery.

BACKGROUND AND PURPOSE: This cross-sectional cohort study aims at investigating young ischaemic stroke survivors with good physical recovery 7 years post-stroke in order to analyze the relation between late cognitive ability and employment. METHODS: Consecutive ischaemic stroke survivors participating in the Sahlgrenska Academy Study on Ischemic Stroke, <55 years of age at stroke onset, and with no or minimal persisting neurological deficits corresponding to a score ≤2 on the National Institutes of Health Stroke Scale at long-term follow-up 7 years post-stroke were included. At this follow-up, the participants were assessed with respect to general cognitive function, processing speed, executive functions, cardiovascular risk factors, self-reported employment, cognitive difficulties, fatigue, depressive symptoms, anxiety and physical function. RESULTS: Seven years post-stroke 112/142 (79%) had part-time or full-time work and 30/142 (21%) had full-time disability pension or sick leave. Compared to those with full-time disability pension or sick leave, participants with current employment demonstrated significantly better performance with respect to general cognitive function and processing speed, and significantly lower self-ratings for cognitive difficulties, physical limitations, fatigue and depressed mood. Multivariable logistic regression selected self-rated memory (odds ratio [OR] 2.61, 95% confidence interval [CI] 1.61-4.21), processing speed (OR 3.50, 95% CI 1.67-7.33) and self-rated communication skills (OR 3.46, 95% CI 1.75-6.85) as most important correlates (area under the curve 0.83-0.87) of having current employment. CONCLUSION: This study indicates that cognitive dysfunction is an important contributor to long-term work disability amongst young stroke survivors with good physical recovery.

Proinflammatory protein signatures in cryptogenic and large artery atherosclerosis stroke.

OBJECTIVES: The cause of ischemic stroke remains unknown, cryptogenic, in 25% of young and middle-aged patients. We hypothesized that if atherosclerosis is prominent in cryptogenic stroke, it would have a similar proinflammatory protein signature as large artery atherosclerosis (LAA) stroke. MATERIALS & METHODS: Blood was collected in the acute phase and after 3 months from cryptogenic (n = 162) and LAA (n = 73) stroke patients aged 18-69 years and once from age-matched controls (n = 235). Cryptogenic stroke was divided into Framingham Risk Score (FRS) quartiles to compare low and high risk of atherosclerosis. Plasma concentrations of 25 proteins were analyzed using a Luminex multiplex assay. The discriminating properties were assessed with discriminant analysis and C-statistics. RESULTS: We identified proteins that separated cryptogenic and LAA stroke from controls (area under the curves, AUCs ≥ 0.85). For both subtypes, RANTES, IL-4, and IFN-γ contributed the most at both time points. These associations were independent of risk factors of atherosclerosis. We also identified proteins that separated cryptogenic strokes in the lowest quartile of FRS from those in the highest, and from LAA stroke (AUCs ≥ 0.76), and here eotaxin and MCP-1 contributed the most. CONCLUSIONS: The protein signature separating cases from controls was different from the signature separating cryptogenic stroke with low risk of atherosclerosis from those with high risk and from LAA stroke. This suggests that increased RANTES, IL-4, and IFN-γ in stroke may not be primarily related to atherosclerosis, whereas increased eotaxin and MCP-1 in cryptogenic stroke may be markers of occult atherosclerosis as the underlying cause.

Big Data Approaches to Phenotyping Acute Ischemic Stroke Using Automated Lesion Segmentation of Multi-Center Magnetic Resonance Imaging Data.

Background and Purpose- We evaluated deep learning algorithms' segmentation of acute ischemic lesions on heterogeneous multi-center clinical diffusion-weighted magnetic resonance imaging (MRI) data sets and explored the potential role of this tool for phenotyping acute ischemic stroke. Methods- Ischemic stroke data sets from the MRI-GENIE (MRI-Genetics Interface Exploration) repository consisting of 12 international genetic research centers were retrospectively analyzed using an automated deep learning segmentation algorithm consisting of an ensemble of 3-dimensional convolutional neural networks. Three ensembles were trained using data from the following: (1) 267 patients from an independent single-center cohort, (2) 267 patients from MRI-GENIE, and (3) mixture of (1) and (2). The algorithms' performances were compared against manual outlines from a separate 383 patient subset from MRI-GENIE. Univariable and multivariable logistic regression with respect to demographics, stroke subtypes, and vascular risk factors were performed to identify phenotypes associated with large acute diffusion-weighted MRI volumes and greater stroke severity in 2770 MRI-GENIE patients. Stroke topography was investigated. Results- The ensemble consisting of a mixture of MRI-GENIE and single-center convolutional neural networks performed best. Subset analysis comparing automated and manual lesion volumes in 383 patients found excellent correlation (ρ=0.92; P<0.0001). Median (interquartile range) diffusion-weighted MRI lesion volumes from 2770 patients were 3.7 cm3 (0.9-16.6 cm3). Patients with small artery occlusion stroke subtype had smaller lesion volumes ( P<0.0001) and different topography compared with other stroke subtypes. Conclusions- Automated accurate clinical diffusion-weighted MRI lesion segmentation using deep learning algorithms trained with multi-center and diverse data is feasible. Both lesion volume and topography can provide insight into stroke subtypes with sufficient sample size from big heterogeneous multi-center clinical imaging phenotype data sets.

Homeostasis model assessment of insulin resistance and outcome of ischemic stroke in non-diabetic patients - a prospective observational study.

BACKGROUND: Insulin resistance (IR) in relation to diabetes is a risk factor for ischemic stroke (IS), whereas less is known about non-diabetic IR and outcome after IS. METHODS: In non-diabetic IS (n = 441) and controls (n = 560) from the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), IR was investigated in relation to IS severity and functional outcome. IR was evaluated acutely and after 3 months using the Homeostasis model assessment of IR (HOMA-IR). Stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS). Functional outcome was evaluated using the modified Rankin Scale (mRS) after 3 months, 2 and 7 years. Associations were evaluated by logistic regression. RESULTS: Higher acute and 3-month HOMA-IR was observed in IS compared to the controls (both p < 0.001) and in severe compared to mild IS (both p < 0.05). High acute HOMA-IR was associated with poor outcome (mRS 3-6) after 3 months and 7 years [crude Odds ratios (ORs), 95% confidence intervals (CIs) 1.50, 1.07-2.11 and 1.59, 1.11-2.30, respectively], but not after 2 years. These associations lost significance after adjustment for all covariates including initial stroke severity. In the largest IS subtype (cryptogenic stroke), acute HOMA-IR was associated with poor outcome after 2 years also after adjustment for age and stroke severity (OR 2.86, 95% CI 1.01-8.12). CONCLUSIONS: In non-diabetic IS patients, HOMA-IR was elevated and related to stroke severity, but after adjustment for IS severity, the associations between HOMR-IR and poor outcome lost significance. This could suggest that elevated IR mostly is a part of the acute IS morbidity. However, in the subgroup of cryptogenic stroke, the associations with poor outcome withstood correction for stroke severity.

Long-term progression of white matter hyperintensities in ischemic stroke.

OBJECTIVES: Studies on long-term progression of white matter hyperintensities (WMH) after ischemic stroke are scarce. Here, we sought to investigate this progression and its predictors in a cohort presenting with ischemic stroke before 70 years of age. MATERIALS AND METHODS: Participants in the Sahlgrenska Academy Study on Ischemic Stroke who underwent magnetic resonance imaging (MRI) of the brain at index stroke were examined by MRI again after 7 years (n = 188, mean age 53 years at index stroke, 35% females). WMH at index stroke and progression were assessed according to Fazekas' grades and the WMH change scale. Stroke subtype was classified according to TOAST. RESULTS: Marked WMH at index stroke were present in 20% of the participants and were significantly associated with age, hypertension, and subtype. Progression of WMH after 7 years was observed in 63% and 35% of the participants for subcortical and periventricular locations, respectively. Significant independent predictors of progression were age and marked WMH at baseline for both locations, whereas no significant associations were detected for vascular risk factors or subtype in multivariable analyses. In participants with no or only mild WMH at baseline, 20% showed marked WMH at follow-up. Age and hypertension, but not subtype, were independently associated with this acquisition of marked WMH. CONCLUSIONS: Age and marked WMH at index stroke, but not stroke subtype, predicted long-term WMH progression after ischemic stroke before 70 years of age, whereas age and hypertension predicted acquisition of marked WMH in those with no or only mild WMH at baseline.

Stroke survivors' long-term QALY-weights in relation to their spouses' QALY-weights and informal support: a cross-sectional study.

BACKGROUND: Healthcare interventions that have positive effects on the stroke survivors' health-related quality of life (HRQoL) and quality-adjusted life-years (QALYs) might also have positive effects for their spouses in terms of improved HRQoL and/or reduced spousal informal support. However, knowledge about stroke survivors' HRQoL and QALY and the consequences for their spouses' HRQoL and QALY is limited. Therefore, the aim of this study was to describe the HRQoL and QALY-weights in dyads of stroke survivors in comparison with dyads of healthy controls, and to study the relationship between the stroke survivors' QALY-weights and consequences for spouses in terms of QALY-weight and annual cost of informal support, using a long-term perspective. METHODS: Data on stroke survivors, controls, and spouses were collected from the seven-year follow-up of the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). HRQoL was assessed by the SF-36, and the preference-based health state values were assessed with the SF-6D. The magnitude of the support was assessed with a study specific time-diary. An ordinary least squares (OLS) regression was used to estimate the association between stroke survivors' and spouses' QALY-weights. A two-part econometric model was used to estimate the association between stroke survivors' QALY-weights and the time spent and cost of spouses' informal support. RESULTS: Cohabitant dyads of 248 stroke survivors' aged <70 at stroke onset and 245 controls were included in the study. Stroke survivors had lower HRQoL in the SF-36 domains physical functioning, physical role, general health, vitality (P < 0.001), and social functioning (P = 0.005) in comparison with their cohabitant spouses. There was no significant difference in HRQoL for the dyads of controls. The results from the regression analyses showed that lower QALY-weights of the stroke survivors were associated with lower QALY-weights of their spouses and increased annual cost of spousal informal support. CONCLUSION: Our results show that the QALY-weights for stroke survivors had consequences for their spouses in terms of annual cost of spousal informal support and QALY-weights. Hence, economic evaluation of interventions that improve the HRQoL of the stroke survivors but ignore the consequences for their spouses may underestimate the value of the intervention.

Long-term QALY-weights among spouses of dependent and independent midlife stroke survivors.

PURPOSE: The aim of this study was to investigate whether the dependency of midlife stroke survivors had any long-term impact on their spouses' QALY-weights. METHOD: Data on stroke survivors, controls, and spouses were collected from the 7-year follow-up of the Sahlgrenska Academy Study on Ischemic Stroke. Health-related quality of life was assessed by the SF-36, and the preference-based health state values were assessed with the SF-6D. Spouses of dependent and independent stroke survivors were categorized according to their scores on the modified Rankin Scale. An ordinary least squares regression analysis was used to evaluate whether the dependency of the stroke survivors had any impact on the spouses' QALY-weights. RESULT: Cohabitant dyads of 247 stroke survivors aged <70 at stroke onset and 245 dyads of controls were included in the study. Spouses of dependent stroke survivors (n = 50) reported a significant lower mean QALY-weight of 0.69 in comparison to spouses of independent stroke survivors (n = 197) and spouses of controls, (n = 245) who both reported a mean QALY-weight of 0.77. The results from the regression analysis showed that higher age of the spouse and dependency of the stroke survivor had a negative association with the spouses' QALY-weights. CONCLUSION: The QALY-weights for spouses of dependent midlife stroke survivors were significantly reduced compared to spouses of independent midlife stroke survivors. This indicates that the inclusion of spouses' QALYs in evaluations of early treatment and rehabilitation efforts to reduce stroke patients' dependency would capture more of the total effect in dyads of stroke survivors.

Spouses of Stroke Survivors Report Reduced Health-Related Quality of Life Even in Long-Term Follow-Up: Results From Sahlgrenska Academy Study on Ischemic Stroke.

BACKGROUND AND PURPOSE: The consequences for the family of stroke survivor are generally studied in a short-term perspective. The aim of this study was to assess long-term aspects of health-related quality of life among spouses of stroke survivors. METHODS: Data on stroke survivors, controls, and spouses were collected from the 7-year follow-up of the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). The health-related quality of life of spouses was assessed by the Short Form-36, and the characteristics of stroke survivors were assessed using the National Institutes of Health Stroke Scale, the Mini-Mental State Examination, the Hospital Anxiety and Depression Scale, the Barthel Index, and the modified Rankin Scale. RESULTS: Dyads of 248 stroke survivors aged <70 at stroke onset and 245 dyads of matched controls were included. Spouses of stroke survivors and spouses of controls had a median age of 64 and 65, respectively; proportion of men was 35% and 34%, respectively. The spouses of stroke survivors reported lower scores in all the mental domains (P=0.045; P<0.001), as well as in the domains of general health (P=0.013) and physical role (P=0.006), compared with the spouses of controls. Predictors of poor physical health of the spouses were their own age and the level of global disability of the stroke survivor. Predictors of poor mental health of the spouses were depressive symptoms, cognitive impairment, and global disability among the stroke survivors. CONCLUSIONS: The health-related quality of life of spouses of stroke survivors is reduced not only during the first years but also in the long-term perspective.

The Barrow Neurological Institute screen for higher cerebral functions in cognitive screening after stroke.

The objective of this study was to evaluate the Barrow Neurological Institute Screen for Higher Cerebral Functions (BNIS) in screening for cognitive dysfunction at long-term follow-up after stroke in young and middle-aged patients. Within the Sahlgrenska Academy Study on Ischemic Stroke Outcome, the BNIS and the Mini-Mental State Examination (MMSE) were administered to 295 consecutive surviving patients seven years after ischemic stroke. All participants were less than 70 years at index stroke. BNIS score less than 47 and an MMSE score less than 29 were chosen to indicate cognitive dysfunction. Two hundred eighty-one (95%) patients completed both tests. The 2 test scores were moderately correlated, and both tests correlated to disability as measured by the modified Rankin Scale. The distribution of the MMSE score was skewed toward the top scores, with a marked ceiling effect, whereas the BNIS score was more normally distributed. Most BNIS subscales showed mean performance around the mid of the scale without ceiling effects. Both tests identified a large proportion of the subjects as cognitive impaired, however, with a substantially larger proportion for the BNIS (89%) compared with the MMSE (65%). We conclude that the BNIS may be a useful screening instrument for cognitive dysfunction after ischemic stroke and that a large proportion of young and middle-aged ischemic stroke survivors showed signs of cognitive dysfunction long after index stroke. Further validations of BNIS against formal neuropsychological testing and studies of the determinants and consequences of long-term cognitive outcome in this patient group are warranted.

Circulating levels of neurofilament light chain as a biomarker of infarct and white matter hyperintensity volumes after ischemic stroke.

Serum neurofilament light chain protein (sNfL) shows promise as a biomarker for infarct size in acute ischemic stroke and for monitoring cerebral small vessel disease (cSVD). However, distinguishing the cSVD contribution after stroke may not be possible due to post-stroke sNfL increase. Additionally, it remains unclear if etiologic subtype differences exist. We measured infarct and white matter hyperintensity (WMH) volumes using MRI at the index stroke in ischemic stroke patients (n = 316, mean age 53 years, 65% males) and at 7-year follow-up (n = 187). Serum NfL concentration was measured in the acute phase (n = 235), at 3-months (n = 288), and 7-years (n = 190) post stroke. In multivariable regression, acute and 3-month sNfL concentrations were associated with infarct volume and time since stroke, but not with stroke etiology or infarct location. Seven years post-stroke, sNfL was associated with WMHs and age, but not with stroke etiology. Nonlinear regression estimated that sNfL peaks around 1 month, and declines by 50% at 3 months, and 99% at 9 months. We conclude that sNfL can indicate infarct volume and time since brain injury in the acute and subacute phases after stroke. Due to the significant post-stroke sNfL increase, several months are needed for reliable assessment of cSVD activity.

Radiomics-Derived Brain Age Predicts Functional Outcome After Acute Ischemic Stroke.

BACKGROUND AND OBJECTIVES: While chronological age is one of the most influential determinants of poststroke outcomes, little is known of the impact of neuroimaging-derived biological "brain age." We hypothesized that radiomics analyses of T2-FLAIR images texture would provide brain age estimates and that advanced brain age of patients with stroke will be associated with cardiovascular risk factors and worse functional outcomes. METHODS: We extracted radiomics from T2-FLAIR images acquired during acute stroke clinical evaluation. Brain age was determined from brain parenchyma radiomics using an ElasticNet linear regression model. Subsequently, relative brain age (RBA), which expresses brain age in comparison with chronological age-matched peers, was estimated. Finally, we built a linear regression model of RBA using clinical cardiovascular characteristics as inputs and a logistic regression model of favorable functional outcomes taking RBA as input. RESULTS: We reviewed 4,163 patients from a large multisite ischemic stroke cohort (mean age = 62.8 years, 42.0% female patients). T2-FLAIR radiomics predicted chronological ages (mean absolute error = 6.9 years, r = 0.81). After adjustment for covariates, RBA was higher and therefore described older-appearing brains in patients with hypertension, diabetes mellitus, a history of smoking, and a history of a prior stroke. In multivariate analyses, age, RBA, NIHSS, and a history of prior stroke were all significantly associated with functional outcome (respective adjusted odds ratios: 0.58, 0.76, 0.48, 0.55; all p-values < 0.001). Moreover, the negative effect of RBA on outcome was especially pronounced in minor strokes. DISCUSSION: T2-FLAIR radiomics can be used to predict brain age and derive RBA. Older-appearing brains, characterized by a higher RBA, reflect cardiovascular risk factor accumulation and are linked to worse outcomes after stroke.

Genetic variation within the interleukin-1 gene cluster and ischemic stroke.

BACKGROUND AND PURPOSE: Evidence is emerging that inflammation plays a key role in the pathophysiology of ischemic stroke (IS). The aim of this study was to investigate whether genetic variation in the interleukin-1α, interleukin-1ß, and interleukin-1 receptor antagonist genes (IL1A, IL1B, and IL1RN) is associated with IS and/or any etiologic subtype of IS. METHODS: Twelve tagSNPs were analyzed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 844 patients with IS and 668 control subjects. IS subtypes were defined according to the Trial of Org 10172 in Acute Stroke Treatment criteria in SAHLSIS. The Lund Stroke Register and the Malmö Diet and Cancer study were used as a replication sample for overall IS (in total 3145 patients and 1793 control subjects). RESULTS: The single nucleotide polymorphism rs380092 in IL1RN showed an association with overall IS in SAHLSIS (OR, 1.21; 95% CI, 1.02-1.43; P=0.03), which was replicated in the Lund Stroke Register and the Malmö Diet and Cancer study sample. An association was also detected in all samples combined (OR, 1.12; 95% CI, 1.04-1.21; P=0.03). Three single nucleotide polymorphisms in IL1RN (including rs380092) were nominally associated with the subtype of cryptogenic stroke in SAHLSIS, but the statistical significance did not remain after correction for multiple testing. Furthermore, increased plasma levels of interleukin-1 receptor antagonist were observed in the subtype of cryptogenic stroke compared with controls. CONCLUSIONS: This comprehensive study, based on a tagSNP approach and replication, presents support for the role of IL1RN in overall IS.

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.

Association of Stroke Lesion Pattern and White Matter Hyperintensity Burden With Stroke Severity and Outcome.

BACKGROUND AND OBJECTIVES: To examine whether high white matter hyperintensity (WMH) burden is associated with greater stroke severity and worse functional outcomes in lesion pattern-specific ways. METHODS: MR neuroimaging and NIH Stroke Scale data at index stroke and the modified Rankin Scale (mRS) score at 3-6 months after stroke were obtained from the MRI-Genetics Interface Exploration study of patients with acute ischemic stroke (AIS). Individual WMH volume was automatically derived from fluid-attenuated inversion recovery images. Stroke lesions were automatically segmented from diffusion-weighted imaging (DWI) images, parcellated into atlas-defined brain regions and further condensed to 10 lesion patterns via machine learning-based dimensionality reduction. Stroke lesion effects on AIS severity and unfavorable outcomes (mRS score >2) were modeled within purpose-built Bayesian linear and logistic regression frameworks. Interaction effects between stroke lesions and a high vs low WMH burden were integrated via hierarchical model structures. Models were adjusted for age, age2, sex, total DWI lesion and WMH volumes, and comorbidities. Data were split into derivation and validation cohorts. RESULTS: A total of 928 patients with AIS contributed to acute stroke severity analyses (age: 64.8 [14.5] years, 40% women) and 698 patients to long-term functional outcome analyses (age: 65.9 [14.7] years, 41% women). Stroke severity was mainly explained by lesions focused on bilateral subcortical and left hemispherically pronounced cortical regions across patients with both a high and low WMH burden. Lesions centered on left-hemispheric insular, opercular, and inferior frontal regions and lesions affecting right-hemispheric temporoparietal regions had more pronounced effects on stroke severity in case of high compared with low WMH burden. Unfavorable outcomes were predominantly explained by lesions in bilateral subcortical regions. In difference to the lesion location-specific WMH effects on stroke severity, higher WMH burden increased the odds of unfavorable outcomes independent of lesion location. DISCUSSION: Higher WMH burden may be associated with an increased stroke severity in case of stroke lesions involving left-hemispheric insular, opercular, and inferior frontal regions (potentially linked to language functions) and right-hemispheric temporoparietal regions (potentially linked to attention). Our findings suggest that patients with specific constellations of WMH burden and lesion locations may have greater benefits from acute recanalization treatments. Future clinical studies are warranted to systematically assess this assumption and guide more tailored treatment decisions.

Sex-specific lesion pattern of functional outcomes after stroke.

Stroke represents a considerable burden of disease for both men and women. However, a growing body of literature suggests clinically relevant sex differences in the underlying causes, presentations and outcomes of acute ischaemic stroke. In a recent study, we reported sex divergences in lesion topographies: specific to women, acute stroke severity was linked to lesions in the left-hemispheric posterior circulation. We here determined whether these sex-specific brain manifestations also affect long-term outcomes. We relied on 822 acute ischaemic patients [age: 64.7 (15.0) years, 39% women] originating from the multi-centre MRI-GENIE study to model unfavourable outcomes (modified Rankin Scale >2) based on acute neuroimaging data in a Bayesian hierarchical framework. Lesions encompassing bilateral subcortical nuclei and left-lateralized regions in proximity to the insula explained outcomes across men and women (area under the curve = 0.81). A pattern of left-hemispheric posterior circulation brain regions, combining left hippocampus, precuneus, fusiform and lingual gyrus, occipital pole and latero-occipital cortex, showed a substantially higher relevance in explaining functional outcomes in women compared to men [mean difference of Bayesian posterior distributions (men - women) = -0.295 (90% highest posterior density interval = -0.556 to -0.068)]. Once validated in prospective studies, our findings may motivate a sex-specific approach to clinical stroke management and hold the promise of enhancing outcomes on a population level.

Plasma C3 and C3a levels in cryptogenic and large-vessel disease stroke: associations with outcome.

BACKGROUND AND PURPOSE: Inflammation seems to be a key player in the pathophysiology of stroke. In this study, we compared plasma C3 and C3a levels in cryptogenic and large-vessel disease (LVD) subtypes of ischemic stroke and control subjects and evaluated their association to outcome at 3 months and 2 years. METHODS: C3 and C3a levels in plasma of 79 cryptogenic stroke and 73 LVD stroke patients, sampled within 10 days and at 3 months after stroke, and age- and sex-matched control subjects from the Sahlgrenska Academy Study on Ischemic Stroke were measured by ELISA. Functional outcome was assessed with the modified Rankin Scale. RESULTS: Plasma C3 was increased in both stroke groups at both time points. Systemic elevation of C3a was limited to the acute phase in the cryptogenic stroke group, whereas plasma C3a levels in the LVD group were also elevated at the 3-month follow-up. In the LVD group, plasma C3 levels in the upper third at the 3-month follow-up were associated with an unfavorable outcome after 3 months independently of age and sex: odds ratio (OR) 5.56; 95% confidence interval (CI) 1.03-29.93; p = 0.045; as well as after 2 years: OR 4.75; 95% CI 1.11-20.30; p = 0.036. In the cryptogenic stroke group, high plasma C3a levels in the acute phase were associated with an unfavorable outcome after 3 months: OR 3.75; 95% CI 1.01-13.96; p = 0.049 in univariate analysis but not after adjustment for age and sex (p = 0.050). CONCLUSIONS: Plasma C3 and C3a levels are elevated in cryptogenic and LVD stroke and the predictive value of these markers may depend on stroke subtype. Further studies on the role of the complement system in ischemic stroke outcome based on larger patient populations and controlling for the effect of infections, are clearly warranted.

Outcome after acute ischemic stroke is linked to sex-specific lesion patterns.

Acute ischemic stroke affects men and women differently. In particular, women are often reported to experience higher acute stroke severity than men. We derived a low-dimensional representation of anatomical stroke lesions and designed a Bayesian hierarchical modeling framework tailored to estimate possible sex differences in lesion patterns linked to acute stroke severity (National Institute of Health Stroke Scale). This framework was developed in 555 patients (38% female). Findings were validated in an independent cohort (n = 503, 41% female). Here, we show brain lesions in regions subserving motor and language functions help explain stroke severity in both men and women, however more widespread lesion patterns are relevant in female patients. Higher stroke severity in women, but not men, is associated with left hemisphere lesions in the vicinity of the posterior circulation. Our results suggest there are sex-specific functional cerebral asymmetries that may be important for future investigations of sex-stratified approaches to management of acute ischemic stroke.