Effect of intravenous alteplase on ischaemic lesion water homeostasis

Temporal and Spatial Dynamics of Ischemic Stroke Lesions after Acute Therapy: A Comprehensive Edema Assessment Using Combined 1H- and 23Na-MRI

INTRODUCTION

Ischemic cerebral stroke initiates a complex cascade of pathophysiological events, involving various forms of molecular shifts and edema. Early intervention is pivotal in minimizing tissue loss and improving clinical outcomes. This study explores the temporal and spatial evolution of tissue sodium concentration (TSC) in acute ischemic lesions after acute therapy using 23Na-MRI in addition to conventional 1H-MRI.

METHODS

Prospectively, from examined 58 patients with acute ischemic stroke with a combined 1H/23Na-MRI within 72 h of symptom onset after receiving acute therapy, 31 patients were included in the evaluation of this study. After co-registration of the 23Na-MRI images to the morphological 1H-MRI images, manual segmentation of the ischemic lesions was performed, and the ADC and TSC measurements were quantified and correlated with the time of onset and lesion volume.

RESULTS

The mean TSC in ischemic lesions correlated positively with lesion volume (r = 0.52, p = 0.002) and showed a significant association with the time of stroke onset (r = 0.8, p < 0.001). Patients who were treated only with intravenous rtPA showed homogenous sodium signal intensity in the ischemic lesions, whereas the patients who received mechanical recanalization exhibited distinctive sodium signal intensity patterns with focal significant TSC differences.

CONCLUSION

The integration of 1H- and 23Na-MRI provides a nuanced understanding of temporal and spatial changes due to different types of edema in ischemic stroke lesions following acute treatment. Further exploration of these findings may enhance our understanding of stroke pathophysiology and guide personalized therapeutic interventions.

The Role of Stem Cells as Therapeutics for Ischaemic Stroke

Stroke remains one of the leading causes of death and disability worldwide. Current reperfusion treatments for ischaemic stroke are limited due to their narrow therapeutic window in rescuing ischaemic penumbra. Stem cell therapy offers a promising alternative. As a regenerative medicine, stem cells offer a wider range of treatment strategies, including long-term intervention for chronic patients, through the reparation and replacement of injured cells via mechanisms of differentiation and proliferation. The purpose of this review is to evaluate the therapeutic role of stem cells for ischaemic stroke. This paper discusses the pathology during acute, subacute, and chronic phases of cerebral ischaemic injury, highlights the mechanisms involved in mesenchymal, endothelial, haematopoietic, and neural stem cell-mediated cerebrovascular regeneration, and evaluates the pre-clinical and clinical data concerning the safety and efficacy of stem cell-based treatments. The treatment of stroke patients with different types of stem cells appears to be safe and efficacious even at relatively higher concentrations irrespective of the route and timing of administration. The priming or pre-conditioning of cells prior to administration appears to help augment their therapeutic impact. However, larger patient cohorts and later-phase trials are required to consolidate these findings.

Related Factors of Cerebral Hemorrhage after Cerebral Infarction and the Effect of Atorvastatin Combined with Intensive Nursing Care

Background

Cerebral infarction is a common neurological disease with high incidence, which is the main factor causing death and disability in adults in China. Cerebral hemorrhage transformation is a common clinical complication. High NIHSS score at admission, atrial fibrillation, and small artery occlusion cerebral infarction can increase the risk of cerebral infarction complicated with hemorrhage transformation.

Aim

To explore the related factors of cerebral hemorrhage transformation after cerebral infarction and the value of atorvastatin calcium tablets combined with early intensive care measures.

Methods

In this study, a case-control study was conducted. Sixty patients with hemorrhagic transformation after cerebral infarction admitted to the Department of Neurology of our hospital from January 2017 to June 2021 were selected as the observation group, and 90 patients with cerebral infarction without hemorrhagic transformation during the same period were selected as the control group. The risk factors of hemorrhagic transformation after cerebral infarction were analyzed.

Results

The results of logistic regression model showed that the increased National Institutes of Health Stroke Scale (NIHSS) score at admission, hypertension, atrial fibrillation, TOAST classification of small artery occlusion, and large infarction lesions were the risk factors for hemorrhagic transformation in patients with cerebral infarction (P < 0.05). After 2 weeks and 4 weeks of treatment, the NIHSS scores of the intervention group were lower than those of the conventional group (P < 0.05). NIHSS scores of the two groups after treatment were significantly lower than those before treatment (P < 0.05). After three months of treatment, the patients in the intervention group with GOS score of 5 points accounted for 16.67%, and the patients with GOS score of 4 points accounted for 56.67%. The patients in the conventional group with GOS score of 5 points accounted for 6.67%, and the patients with GOS score of 4 points accounted for 33.33%. The prognosis of the intervention group was better than that of the conventional group on the whole (P < 0.05).

Conclusion

Patients with hypertension, large infarction lesions, high NIHSS score at admission, atrial fibrillation, and small artery occlusion cerebral infarction can increase the risk of bleeding transformation in patients with cerebral infarction. For patients with bleeding transformation, atorvastatin calcium tablets combined with early intensive nursing intervention has a certain value for improving the prognosis of patients.

Early Edema Within the Ischemic Core Is Time-Dependent and Associated With Functional Outcomes of Acute Ischemic Stroke Patients

Objective

To investigate the difference in early edema, quantified by net water uptake (NWU) based on computed tomography (CT) between ischemic core and penumbra and to explore predictors of NWU and test its predictive power for clinical outcome.

Methods

Retrospective analysis was conducted on patients admitted to Ningbo First Hospital with anterior circulation stroke and multi-modal CT. In 154 included patients, NWU of the ischemic core and penumbra were calculated and compared by Mann–Whitney U test. Correlations between NWU and variables including age, infarct time (time from symptom onset to imaging), volume of ischemic core, collateral status, and National Institutes of Health Stroke Scale (NIHSS) scores were investigated by Spearman's correlation analyses. Clinical outcome was defined using the modified Rankin Scale (mRS) at 90 days. Logistic regression and receiver operating characteristic analyses were performed to test the predictive value of NWU. Summary statistics are presented as median (interquartile range), mean (standard deviation) or estimates (95% confidence interval).

Results

The NWU within the ischemic core [6.1% (2.9–9.2%)] was significantly higher than that of the penumbra [1.8% (−0.8–4.0%)]. The only significant predictor of NWU within the ischemic core was infarct time (p = 0.004). The NWU within the ischemic core [odds ratio = 1.23 (1.10–1.39)], the volume of ischemic core [1.04, (1.02–1.06)], age [1.09 (1.01–1.17)], and admission NHISS score [1.05 (1.01–1.09)] were associated with the outcome of patients adjusted for sex and treatment. The predictive power for the outcome of the model was significantly higher when NWU was included (area under the curve 0.875 vs. 0.813, p &lt; 0.05 by Delong test).

Conclusions

Early edema quantified by NWU is relatively limited in the ischemic core and develops in a time-dependent manner. NWU estimates within the ischemic core may help to predict clinical outcomes of patients with acute ischemic stroke.

Impact of intravenous alteplase on sub-angiographic emboli in high-resolution diffusion-weighted imaging following successful thrombectomy

Objective

Thrombus microfragmentation causing peripheral emboli (PE) during mechanical thrombectomy (MT) may modulate treatment effects, even in cases with successful reperfusion. This study aims to investigate whether intravenous alteplase is of potential benefit in reducing PE after successful MT.

Methods

Patients from a prospective study treated at a tertiary care stroke center between 08/2017 and 12/2019 were analyzed. The main inclusion criterion was successful reperfusion after MT (defined as expanded thrombolysis in cerebral infarction (eTICI) scale ≥ 2b50) of large vessel occlusion anterior circulation stroke. All patients received a high-resolution diffusion-weighted imaging (DWI) follow-up 24 h after MT for PE detection. Patients were grouped as “direct MT” (no alteplase) or as MT plus additional intravenous alteplase. The number and volume of ischemic core lesions and PE were then quantified and analyzed.

Results

Fifty-six patients were prospectively enrolled. Additional intravenous alteplase was administered in 46.3% (26/56). There were no statistically significant differences of PE compared by groups of direct MT and additional intravenous alteplase administration regarding mean numbers (12.1, 95% CI 8.6–15.5 vs. 11.1, 95% CI 7.0–15.1; p = 0.701), and median volume (0.70 mL, IQR 0.21–1.55 vs. 0.39 mL, IQR 0.10–1.62; p = 0.554). In uni- and multivariable linear regression analysis, higher eTICI scores were significantly associated with reduced PE, while the administration of alteplase was neither associated with numbers nor volume of peripheral emboli. Additional alteplase did not alter reperfusion success.

Conclusions

Intravenous alteplase neither affects the number nor volume of sub-angiographic DWI-PE after successful endovascular reperfusion. In the light of currently running randomized trials, further studies are warranted to validate these findings.

Key Points

• Thrombus microfragmentation during endovascular stroke treatment may cause peripheral emboli that are only detectable on diffusion-weighted imaging and may directly compromise treatment effects.

• In this prospective study, the application of intravenous alteplase did not influence the occurrence of peripheral emboli detected on high-resolution diffusion-weighted imaging.

• A higher degree of recanalization was associated with a reduced number and volume of peripheral emboli and better functional outcome, while contrariwise, peripheral emboli did not modify the effect of recanalization on modified Rankin Scale scores at day 90.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-07980-0.

Blood-Brain Barrier Damage in Ischemic Stroke and Its Regulation by Endothelial Mechanotransduction

Ischemic stroke, a major cause of mortality in the United States, often contributes to disruption of the blood-brain barrier (BBB). The BBB along with its supportive cells, collectively referred to as the “neurovascular unit,” is the brain’s multicellular microvasculature that bi-directionally regulates the transport of blood, ions, oxygen, and cells from the circulation into the brain. It is thus vital for the maintenance of central nervous system homeostasis. BBB disruption, which is associated with the altered expression of tight junction proteins and BBB transporters, is believed to exacerbate brain injury caused by ischemic stroke and limits the therapeutic potential of current clinical therapies, such as recombinant tissue plasminogen activator. Accumulating evidence suggests that endothelial mechanobiology, the conversion of mechanical forces into biochemical signals, helps regulate function of the peripheral vasculature and may similarly maintain BBB integrity. For example, the endothelial glycocalyx (GCX), a glycoprotein-proteoglycan layer extending into the lumen of bloods vessel, is abundantly expressed on endothelial cells of the BBB and has been shown to regulate BBB permeability. In this review, we will focus on our understanding of the mechanisms underlying BBB damage after ischemic stroke, highlighting current and potential future novel pharmacological strategies for BBB protection and recovery. Finally, we will address the current knowledge of endothelial mechanotransduction in BBB maintenance, specifically focusing on a potential role of the endothelial GCX.

A Comparison of T2 Relaxation-Based MRI Stroke Timing Methods in Hyperacute Ischemic Stroke Patients: A Pilot Study

Background:

T₂ relaxation-based magnetic resonance imaging (MRI) signals may provide onset time for acute ischemic strokes with an unknown onset. The ability of visual and quantitative MRI-based methods in a cohort of hyperacute ischemic stroke patients was studied.

Methods:

A total of 35 patients underwent 3T (3 Tesla) MRI (<9-hour symptom onset). Diffusion-weighted (DWI), apparent diffusion coefficient (ADC), T₁-weighted (T₁w), T₂-weighted (T₂w), and T₂ relaxation time (T₂) images were acquired. T₂-weighted fluid attenuation inversion recovery (FLAIR) images were acquired for 17 of these patients. Image intensity ratios of the average intensities in ischemic and non-ischemic reference regions were calculated for ADC, DWI, T₂w, T₂ relaxation, and FLAIR images, and optimal image intensity ratio cut-offs were determined. DWI and FLAIR images were assessed visually for DWI/FLAIR mismatch.

Results:

The T₂ relaxation time image intensity ratio was the only parameter with significant correlation with stroke duration (r = 0.49, P = .003), an area under the receiver operating characteristic curve (AUC = 0.77, P < .0001), and an optimal cut-off (T₂ ratio = 1.072) that accurately identified patients within the 4.5-hour thrombolysis treatment window with sensitivity of 0.74 and specificity of 0.74. In the patients with the additional FLAIR, areas under the precision-recall-gain curve (AUPRG) and F₁ scores showed that the T₂ relaxation time ratio (AUPRG = 0.60, F₁ = 0.73) performed considerably better than the FLAIR ratio (AUPRG = 0.39, F₁ = 0.57) and the visual DWI/FLAIR mismatch (F₁ = 0.25).

Conclusions:

Quantitative T₂ relaxation time is the preferred MRI parameter in the assessment of patients with unknown onset for treatment stratification.