This review covers the pathogenesis of ischemic stroke and future directions regarding therapeutic options after injury. Ischemic stroke is a devastating disease process affecting millions of people ...worldwide every year. The mechanisms underlying the pathophysiology of stroke are not fully understood but there is increasing evidence demonstrating the contribution of inflammation to the drastic changes after cerebral ischemia. This inflammation not only immediately affects the infarcted tissue but also causes long-term damage in the ischemic penumbra. Furthermore, the interaction between inflammation and subsequent neurogenesis is not well understood but the close relationship between these two processes has garnered significant interest in the last decade or so. Current approved therapy for stroke involving pharmacological thrombolysis is limited in its efficacy and new treatment strategies need to be investigated. Research aimed at new therapies is largely about transplantation of neural stem cells and using endogenous progenitor cells to promote brain repair. By understanding the interaction between inflammation and neurogenesis, new potential therapies could be developed to further establish brain repair mechanisms.
Apoptosis may contribute to a significant proportion of neuron death following acute brain ischemia (ABI), but the underlying mechanisms are still not fully understood. Brain ischemia may lead to ...stroke, which is one of the main causes of long-term morbidity and mortality in both developed and developing countries. Therefore, stroke prevention and treatment is clinically important. There are two important separate areas of the brain during ABI: the ischemic core and the ischemic penumbra. The ischemic core of the brain experiences a sudden reduction of blood flow, just minutes after ischemic attack with irreversible injury and subsequent cell death. On the other hand, apoptosis within the ischemic penumbra may occur after several hours or days, while necrosis starts in the first hours after the onset of ABI in the ischemic core. ABI is characterized by key molecular events that initiate apoptosis in many cells, such as overproduction of free radicals, Ca2+ overload and excitotoxicity. These changes in cellular homeostasis may trigger either necrosis or apoptosis, which often depends on cell type, cell age, and location in the brain. Apoptosis results in DNA fragmentation, degradation of cytoskeletal and nuclear proteins, cross-linking of proteins, formation of apoptotic bodies, expression of ligands for phagocytic cell receptors and finally uptake by phagocytic cells. This review focuses on recent findings based on animal and human studies regarding the apoptotic mechanisms of neuronal death following ABI and the development of potential neuroprotective agents that reduce morbidity. The effects of statins on stroke prevention and treatment as well as on apoptotic mediators are also considered.
BACKGROUND AND PURPOSE:With the spread of coronavirus disease 2019 (COVID-19) during the current worldwide pandemic, there is mounting evidence that patients affected by the illness may develop ...clinically significant coagulopathy with thromboembolic complications including ischemic stroke. However, there is limited data on the clinical characteristics, stroke mechanism, and outcomes of patients who have a stroke and COVID-19.
METHODS:We conducted a retrospective cohort study of consecutive patients with ischemic stroke who were hospitalized between March 15, 2020, and April 19, 2020, within a major health system in New York, the current global epicenter of the pandemic. We compared the clinical characteristics of stroke patients with a concurrent diagnosis of COVID-19 to stroke patients without COVID-19 (contemporary controls). In addition, we compared patients to a historical cohort of patients with ischemic stroke discharged from our hospital system between March 15, 2019, and April 15, 2019 (historical controls).
RESULTS:During the study period in 2020, out of 3556 hospitalized patients with diagnosis of COVID-19 infection, 32 patients (0.9%) had imaging proven ischemic stroke. Cryptogenic stroke was more common in patients with COVID-19 (65.6%) as compared to contemporary controls (30.4%, P=0.003) and historical controls (25.0%, P<0.001). When compared with contemporary controls, COVID-19 positive patients had higher admission National Institutes of Health Stroke Scale score and higher peak D-dimer levels. When compared with historical controls, COVID-19 positive patients were more likely to be younger men with elevated troponin, higher admission National Institutes of Health Stroke Scale score, and higher erythrocyte sedimentation rate. Patients with COVID-19 and stroke had significantly higher mortality than historical and contemporary controls.
CONCLUSIONS:We observed a low rate of imaging-confirmed ischemic stroke in hospitalized patients with COVID-19. Most strokes were cryptogenic, possibly related to an acquired hypercoagulability, and mortality was increased. Studies are needed to determine the utility of therapeutic anticoagulation for stroke and other thrombotic event prevention in patients with COVID-19.
In a Chinese trial, endovascular thrombectomy at 6 to 24 hours led to more good outcomes than standard care but also to more cerebral hemorrhages. Approximately 20% of patients received intravenous ...thrombolysis.
CT perfusion (CTP) and diffusion or perfusion MRI might assist patient selection for endovascular thrombectomy. We aimed to establish whether imaging assessments of irreversibly injured ischaemic ...core and potentially salvageable penumbra volumes were associated with functional outcome and whether they interacted with the treatment effect of endovascular thrombectomy on functional outcome.
In this systematic review and meta-analysis, the HERMES collaboration pooled patient-level data from all randomised controlled trials that compared endovascular thrombectomy (predominantly using stent retrievers) with standard medical therapy in patients with anterior circulation ischaemic stroke, published in PubMed from Jan 1, 2010, to May 31, 2017. The primary endpoint was functional outcome, assessed by the modified Rankin Scale (mRS) at 90 days after stroke. Ischaemic core was estimated, before treatment with either endovascular thrombectomy or standard medical therapy, by CTP as relative cerebral blood flow less than 30% of normal brain blood flow or by MRI as an apparent diffusion coefficient less than 620 μm2/s. Critically hypoperfused tissue was estimated as the volume of tissue with a CTP time to maximum longer than 6 s. Mismatch volume (ie, the estimated penumbral volume) was calculated as critically hypoperfused tissue volume minus ischaemic core volume. The association of ischaemic core and penumbral volumes with 90-day mRS score was analysed with multivariable logistic regression (functional independence, defined as mRS score 0–2) and ordinal logistic regression (functional improvement by at least one mRS category) in all patients and in a subset of those with more than 50% endovascular reperfusion, adjusted for baseline prognostic variables. The meta-analysis was prospectively designed by the HERMES executive committee, but not registered.
We identified seven studies with 1764 patients, all of which were included in the meta-analysis. CTP was available and assessable for 591 (34%) patients and diffusion MRI for 309 (18%) patients. Functional independence was worse in patients who had CTP versus those who had diffusion MRI, after adjustment for ischaemic core volume (odds ratio OR 0·47 95% CI 0·30–0·72, p=0·0007), so the imaging modalities were not pooled. Increasing ischaemic core volume was associated with reduced likelihood of functional independence (CTP OR 0·77 0·69–0·86 per 10 mL, pinteraction=0·29; diffusion MRI OR 0·87 0·81–0·94 per 10 mL, pinteraction=0·94). Mismatch volume, examined only in the CTP group because of the small numbers of patients who had perfusion MRI, was not associated with either functional independence or functional improvement. In patients with CTP with more than 50% endovascular reperfusion (n=186), age, ischaemic core volume, and imaging-to-reperfusion time were independently associated with functional improvement. Risk of bias between studies was generally low.
Estimated ischaemic core volume was independently associated with functional independence and functional improvement but did not modify the treatment benefit of endovascular thrombectomy over standard medical therapy for improved functional outcome. Combining ischaemic core volume with age and expected imaging-to-reperfusion time will improve assessment of prognosis and might inform endovascular thrombectomy treatment decisions.
Medtronic.
Brain infarction causes tissue death by ischemia due to occlusion of the cerebral vessels and recent work has shown that post stroke inflammation contributes significantly to the development of ...ischemic pathology. Because secondary damage by brain inflammation may have a longer therapeutic time window compared to the rescue of primary damage following arterial occlusion, controlling inflammation would be an obvious therapeutic target. A substantial amount of experimentall progress in this area has been made in recent years. However, it is difficult to elucidate the precise mechanisms of the inflammatory responses following ischemic stroke because inflammation is a complex series of interactions between inflammatory cells and molecules, all of which could be either detrimental or beneficial. We review recent advances in neuroinflammation and the modulation of inflammatory signaling pathways in brain ischemia. Potential targets for treatment of ischemic stroke will also be covered. The roles of the immune system and brain damage versus repair will help to clarify how immune modulation may treat stroke.
Neutrophils have key roles in ischemic brain injury, thrombosis, and atherosclerosis. As such, neutrophils are of great interest as targets to treat and prevent ischemic stroke. After stroke, ...neutrophils respond rapidly promoting blood–brain barrier disruption, cerebral edema, and brain injury. A surge of neutrophil-derived reactive oxygen species, proteases, and cytokines are released as neutrophils interact with cerebral endothelium. Neutrophils also are linked to the major processes that cause ischemic stroke, thrombosis, and atherosclerosis. Thrombosis is promoted through interactions with platelets, clotting factors, and release of prothrombotic molecules. In atherosclerosis, neutrophils promote plaque formation and rupture by generating oxidized-low density lipoprotein, enhancing monocyte infiltration, and degrading the fibrous cap. In experimental studies targeting neutrophils can improve stroke. However, early human studies have been met with challenges, and suggest that selective targeting of neutrophils may be required. Several properties of neutrophil are beneficial and thus may important to preserve in patients with stroke including antimicrobial, antiinflammatory, and neuroprotective functions.
actor associated with outcomes and mortality in COVID-19 patients includes cardiovascular and cerebrovascular comorbidities but the underlying mechanisms are still hypothetical 1. We report the case ...of a 73-year-old patient who developed within a week after the onset of respiratory symptoms related to SARS-CoV2 infection, an acute ischemic stroke (AIS) complicating a large floating thrombus within the common carotid artery. The patient has no specific past medical history, no treatment and no vascular risk factors. He presented at the emergency department on March 25th for the onset of fever and dry cough. Clinical evaluation was reassuring and the patient was discharged home. He was readmitted 7 days later for the acute onset of aphasia and right hemiparesis evolving for 9 hours. On admission, the patient was in respiratory distress, and neurological examination revealed a left middle cerebral artery (MCA) syndrome with a NIH stroke scale (NIHSS) of 10. Chest CT showed ground glass opacities typically reported in SARS-CoV2 infection, which was subsequently confirmed by real-time reverse transcriptase–polymerase chain reaction assay on a nasopharyngeal swab sample. Brain Computer Tomography (CT), CT angiography (CTA) and CT perfusion, performed on a 64-channel scanner (Optima, General Electric, USA), showed subtle cortical left frontal hypoattenuation with more extended surrounding hypoperfusion and distal occlusion of branch. CT perfusion was acquired before CTA, and both were performed using, for each, a 40 cc-bolus of iodine contrast injected at a 5 cc/sec rate (iobitridol 350, Guerbet, France), pushed by 40 cc of physiological serum. Cervical CTA also revealed a large intraluminal floating thrombus appended to a hypoattenuated non-stenosing plaque of the left common carotid artery wall. Dedicated wall imaging with 3 T MRI (Skyra, Siemens, Germany) and Doppler ultrasoonography confirmed the diagnosis of a large thrombus adherent to a thin atheromatous plaque. Of note, those examination disclosed no ulceration, plaque hemorrhage or circumferential gadolinium enhancement of the wall potentially suggestive of arteritis. Diffusion-Weighted Imaging performed 2 days later confirmed the diagnosis of multiple AIS with foci of hyperintensity scattered within left carotid territory.
The prevalence of stroke is high in both developing and developed nations. It causes a heavy social and financial burden to the sufferers and their caregivers. Thrombolytic therapy is the only ...pharmacological treatment available for stroke. However, thrombolytic agents do not provide substantial improvement on long term motor and cognitive disabilities. Thus, there is a need to explore for new compounds that can halt or reverse the deterioration of neurons in the stroke patients’ brain. Polydatin, a precursor of resveratrol, is a natural stilbene commonly found in food. This review article describes how different parameters were altered with ischemic injury and polydatin treatment, why it is important and how it could be beneficial or useful in future studies. Our review of polydatin provides convincing evidence regarding the potential of polydatin to be developed into preventive or therapeutic products for ischemic stroke. Nevertheless, additional studies are necessary in order to properly elucidate the biological mechanisms of polydatin, especially its molecular mechanisms of protection and target proteins, in cerebral ischemia.
This review outlines the most frequently used rodent stroke models and discusses their strengths and shortcomings. Mimicking all aspects of human stroke in one animal model is not feasible because ...ischemic stroke in humans is a heterogeneous disorder with a complex pathophysiology. The transient or permanent middle cerebral artery occlusion (MCAo) model is one of the models that most closely simulate human ischemic stroke. Furthermore, this model is characterized by reliable and well-reproducible infarcts. Therefore, the MCAo model has been involved in the majority of studies that address pathophysiological processes or neuroprotective agents. Another model uses thromboembolic clots and thus is more convenient for investigating thrombolytic agents and pathophysiological processes after thrombolysis. However, for many reasons, preclinical stroke research has a low translational success rate. One factor might be the choice of stroke model. Whereas the therapeutic responsiveness of permanent focal stroke in humans declines significantly within 3 hours after stroke onset, the therapeutic window in animal models with prompt reperfusion is up to 12 hours, resulting in a much longer action time of the investigated agent. Another major problem of animal stroke models is that studies are mostly conducted in young animals without any comorbidity. These models differ from human stroke, which particularly affects elderly people who have various cerebrovascular risk factors. Choosing the most appropriate stroke model and optimizing the study design of preclinical trials might increase the translational potential of animal stroke models.
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