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

Data-driven biomarkers better associate with stroke motor outcomes than theory-based biomarkers

Chronic motor impairments are a leading cause of disability after stroke. Previous studies have associated motor outcomes with the degree of damage to predefined structures in the motor system, such as the corticospinal tract. However, such theory-based approaches may not take full advantage of the information contained in clinical imaging data. The present study uses data-driven approaches to model chronic motor outcomes after stroke and compares the accuracy of these associations to previously-identified theory-based biomarkers. Using a cross-validation framework, regression models were trained using lesion masks and motor outcomes data from 789 stroke patients from the Enhancing NeuroImaging Genetics through Meta Analysis (ENIGMA) Stroke Recovery Working Group. Using the explained variance metric to measure the strength of the association between chronic motor outcomes and imaging biomarkers, we compared theory-based biomarkers, like lesion load to known motor tracts, to three data-driven biomarkers: lesion load of lesion-behaviour maps, lesion load of structural networks associated with lesion-behaviour maps, and measures of regional structural disconnection. In general, data-driven biomarkers had stronger associations with chronic motor outcomes accuracy than theory-based biomarkers. Data-driven models of regional structural disconnection performed the best of all models tested (R 2 = 0.210, P < 0.001), performing significantly better than the theory-based biomarkers of lesion load of the corticospinal tract (R 2 = 0.132, P < 0.001) and of multiple descending motor tracts (R 2 = 0.180, P < 0.001). They also performed slightly, but significantly, better than other data-driven biomarkers including lesion load of lesion-behaviour maps (R 2 = 0.200, P < 0.001) and lesion load of structural networks associated with lesion-behaviour maps (R 2 = 0.167, P < 0.001). Ensemble models - combining basic demographic variables like age, sex, and time since stroke - improved the strength of associations for theory-based and data-driven biomarkers. Combining both theory-based and data-driven biomarkers with demographic variables improved predictions, and the best ensemble model achieved R 2 = 0.241, P < 0.001. Overall, these results demonstrate that out-of-sample associations between chronic motor outcomes and data-driven imaging features, particularly when lesion data is represented in terms of structural disconnection, are stronger than associations between chronic motor outcomes and theory-based biomarkers. However, combining both theory-based and data-driven models provides the most robust associations.

Regional homogeneity alterations in multifrequency bands in patients with basal ganglia stroke: A resting-state functional magnetic resonance imaging study

Objective

The aim of this study was to investigate the spontaneous regional neural activity abnormalities in patients with acute basal ganglia ischemic stroke (BGIS) using a multifrequency bands regional homogeneity (ReHo) method and to explore whether the alteration of ReHo values was associated with clinical characteristics.

Methods

In this study, 34 patients with acute BGIS and 44 healthy controls (HCs) were recruited. All participants were examined by resting-state functional magnetic resonance imaging (rs-fMRI). The ReHo method was used to detect the alterations of spontaneous neural activities in patients with acute BGIS. A two-sample t-test comparison was performed to compare the ReHo value between the two groups, and a Pearson correlation analysis was conducted to assess the relationship between the regional neural activity abnormalities and clinical characteristics.

Results

Compared with the HCs, the patients with acute BGIS showed increased ReHo in the left caudate and subregions such as the right caudate and left putamen in conventional frequency bands. In the slow-5 frequency band, patients with BGIS showed decreased ReHo in the left medial cingulum of BGIS compared to the HCs and other subregions such as bilateral caudate and left putamen. No brain regions with ReHo alterations were found in the slow-4 frequency band. Moreover, we found that the ReHo value of left caudate was positively correlated with the NIHSS score.

Conclusion

Our findings revealed the alterations of ReHo in patients with acute BGIS in a specific frequency band and provided a new insight into the pathogenesis mechanism of BGIS. This study demonstrated the frequency-specific characteristics of ReHo in patients with acute BGIS, which may have a positive effect on the future neuroimaging studies.

Knockdown of NRSF Alleviates Ischemic Brain Injury and Microvasculature Defects in Diabetic MCAO Mice

Diabetes is one of the well-established risk factors of stroke and is associated with a poor outcome in patients with stroke. Previous studies have shown that the expression of neuron restrictive silencer factor (NRSF) is elevated in diabetes as well as ischemic stroke. However, the role of NRSF in regulating an outcome of diabetic ischemic stroke has not been completely understood. Here, we hypothesized that diabetes-induced NRSF elevation can aggravate brain injury and cognition impairment in ischemic stroke. The diabetic ischemic stroke mice model was established by 8 weeks of high-fat-diet feeding and 5 days of streptozotocin injection followed by 30 min of middle cerebral artery occlusion (MCAO). We found that diabetes enhanced the MCAO-induced elevation of NRSF in the hippocampus in accompany with an elevation of its corepressors, HDAC1, and mSin3A, and decrease of β-TrCP. By using histological/immunofluorescence staining and neurobehavioral testing, our results showed that the brain damage and learning/memory impairment were aggravated in diabetic ischemic mice but significantly attenuated after stereotaxic injection of NRSF-shRNA. Meanwhile, by performing whole-brain clearing with PEGASOS, microvascular reconstruction, western blotting, and ELISA, we found that NRSF-shRNA markedly alleviated the vasculature disorders and rescued the suppression of NRP-1, VEGF, and VEGFR2 in the hippocampus of diabetic ischemic mice. Therefore, our results demonstrated for the first time that the elevation of hippocampal NRSF plays an important role in alleviating brain injury and cognitive disabilities in diabetic ischemic mice, potentially via the reduction of NRP-1/VEGF signaling.

Midline Shift Greater than 3 mm Independently Predicts Outcome After Ischemic Stroke

BACKGROUND

Cerebral edema is associated with worse outcome after acute stroke; however, the minimum clinically relevant threshold remains unknown. This study aimed to identify the minimal degree of midline shift (MLS) that predicts outcome in a cohort encompassing a broad range of patients with acute stroke.

METHODS

Patient-level data from six acute stroke clinical trials were combined with endovascular thrombectomy registries from two academic referral centers, generating a combined cohort of 1977 patients. MLS was extracted from the original trial data or measured on computed tomography or magnetic resonance imaging that was obtained a median of 47.0 h (interquartile range 27.0-75.1 h) after stroke onset. Logistic regression was performed to identify predictors of poor outcome and the minimal clinically relevant MLS threshold.

RESULTS

The presence of MLS was a predictor of poor outcome, independent of baseline clinical and demographic factors (adjusted odds ratio 4.46, 95% confidence interval 3.56-5.59, p < 0.001). Examining the full range of MLS values identified, a value of greater than 3 mm was the critical threshold that significantly predicted poor outcome (adjusted odds ratio 3.20 [1.31-7.82], p = 0.011).

CONCLUSIONS

These results show that the presence of MLS predicts poor outcome and, specifically, MLS value greater than 3 mm is an important threshold across a variety of clinical settings. These findings may have relevance for the design and interpretation of future trials for antiedema therapies.

Importance of the pig as a human biomedical model

[Figure: see text].