Effect of intravenous recombinant tissue plasminogen activator on ischemic stroke lesion size measured by computed tomography. NINDS; The National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Study Group

Anti-miRNA103/107 encapsulated in transferrin-conjugated lipid nanoparticles crosses blood-brain barrier and reduces brain ischemic damage

MicroRNA (miRNA), by post-transcriptionally regulating the expression of genes involved in stroke response, represents important effectors in stroke pathophysiology. Recently, the 103/107 miRNA family emerged as a possible therapeutic target in stroke, as it controls the expression of sodium calcium exchanger 1, a plasma membrane transporter that plays a fundamental role in stroke pathophysiology. Although the neuroprotective properties of this and other miRNAs are promising, several pharmacokinetic drawbacks remain to be faced for the development of a translatable therapy based on small RNAs in CNS diseases. In the present study, to overcome these limitations, the anti-miRNA103/107 was encapsulated in specific preparations of lipid nanoparticles (LNPs), and their effectiveness was evaluated both in an in vitro model of hypoxia represented by primary neuronal cortical cultures exposed to oxygen and glucose deprivation followed by reoxygenation, and in an in vivo model of stroke obtained in rats exposed to transient occlusion of the middle cerebral artery. The results of the present study demonstrated that the encapsulation of anti-miRNA103/107 in transferrin-conjugated PEG-stabilized LNPs allowed the blood-brain barrier crossing and significantly reduced brain ischemic damage. The present achievements pave the way for the exploitation of a systemic intravenous miRNA delivery strategy in stroke therapy.

Efficacy and safety of short-term high dosage dual antiplatelet therapy after 0.6 mg/kg rt-PA intravenous thrombolysis for acute ischemic stroke

OBJECTIVE

To evaluate the efficacy and safety of short-term high-dose of dual antiplatelet therapy after 0.6 mg/kg rt-PA intravenous thrombolysis for acute ischemic stroke (AIS).

METHODS

All 208 patients with AIS were randomized into group 1 (103 cases, after 0.6 mg/kg rt-PA, 300 mg of oral aspirin(ASP) q.d. and 225 mg of oral clopidogrel (CLO) q.d. for for 5 days, then 100 mg of oral ASP q.d. for the next 85 days and 75 mg of oral CLO q.d. for the next 16 days) and group 2 (105 cases, after 0.9 mg/kg rt-PA, 100 mg of oral ASP q.d. for 90 days and 75 mg of oral CLO q.d. for 21 days).The efficacy index was the mRS score, NIHSS score and recurrence risk of stroke, while the safety index was the incidence of bleeding events and mortality. All parameters were evaluated at 30 and 90 days after thrombolysis. Patients whose characteristics may provide the best treatment benefit were further analyzed using the logistic regression model in group 1.

RESULTS

The proportion of mRS scores between 0 and 1 in group 1 was higher than that in group 2 at both 30 days (44.7% vs 32.4%, P < .05) and 90 days (50.5% vs 35.2%, P < .05). Compared to group 2, the proportion of NIHSS scores less than 4 was significantly higher in group 1 at both 30 days (37.9% vs 25.7%, P < .05) and 90 days (46.6% vs 30.5%, P < .05). At 90 days, Group 1 had a lower stroke recurrence risk than Group 2 (3.9% vs 10.5%, P < .05). The incidence of SICH was significantly different between the 2 groups at both 30 days (2.9% vs 9.5%, P < .05) and 90 days (2.9% vs 10.5%, P < .05). However, other bleeding events and mortality rates were not significantly different between the 2 groups. The lower the baseline NIHSS score and the shorter the OTT, the more favorable the outcomes obtained at 90 days.

CONCLUSIONS

Compared to standard doses, short term high-dose dual antiplatelet therapy after 0.6 mg/kg rt-PA intravenous thrombolysis may be a good choice for AIS patients.

Cerebral hemorrhage after thrombolysis in stroke patients with unruptured intracranial aneurysms: a systemic review and meta-analysis

BACKGROUND

For ischemic stroke patients with concomitant unruptured aneurysm, intravenous thrombolysis therapy (IVT) remains a disputable decision. We hence performed a meta-analysis to identify the related brain hemorrhage rate of unruptured aneurysms and the risk ratio for their rupture comparing to stroke patients who do not have aneurysms.

METHODS

A comprehensive search was conducted to identify the studies from the online database from 2000 to September 1st, 2022. Cohort studies were included and assessed by Newcastle-Ottawa Scale (NOS) for quality. The research procedures were subjected to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Fixed-effects model was used based on the heterogeneity tests.

RESULTS

In 10 eligible studies, 7238 ischemic stroke patients were screened, a total of 302 patients with 348 aneurysms were included. 10 studies were eligible for ICH rate analysis, 8 for SAH rate analysis and 7 for risk ratio of stroke patients with unruptured aneurysms. The pooled any ICH rate was 16% (95% CI 11-21%), symptomatic ICH rate was 4% (95% CI 1-7%, I2 = 0.00%, p = 0.90), and 0% (95% CI 0-1%) for aneurysm-related ICH. Subarachnoid hemorrhage was as low as 2% (95% CI 0-5%), while 0% (95% CI 0-2%) directly related to the aneurysm rupture. The risk ratio of ICH in stroke patients with aneurysms was 1.18 (95% CI 0.79-1.77). Additionally, the hemorrhage rate difference was not evident between saccular and fusiform aneurysms due to a lack of details.

CONCLUSIONS

IVT is unlikely to induce hemorrhage of pre-existing unruptured aneurysms in stroke patients. Further randomized control studies are warranted to validate these conclusions.

Preserved structural connectivity mediates the clinical effect of thrombolysis in patients with anterior-circulation stroke

Thrombolysis with recombinant tissue plasminogen activator in acute ischemic stroke aims to restore compromised blood flow and prevent further neuronal damage. Despite the proven clinical efficacy of this treatment, little is known about the short-term effects of systemic thrombolysis on structural brain connectivity. In this secondary analysis of the WAKE-UP trial, we used MRI-derived measures of infarct size and estimated structural network disruption to establish that thrombolysis is associated not only with less infarct growth, but also with reduced loss of large-scale connectivity between grey-matter areas after stroke. In a causal mediation analysis, infarct growth mediated a non-significant 8.3% (CI95% [-8.0, 32.6]%) of the clinical effect of thrombolysis on functional outcome. The proportion mediated jointly through infarct growth and change of structural connectivity, especially in the border zone around the infarct core, however, was as high as 33.4% (CI95% [8.8, 77.4]%). Preservation of structural connectivity is thus an important determinant of treatment success and favourable functional outcome in addition to lesion volume. It might, in the future, serve as an imaging endpoint in clinical trials or as a target for therapeutic interventions.

Impact of the COVID-19 Pandemic on Emergency Department Use: Focus on Patients Requiring Urgent Revascularization

Background

The novel coronavirus (2019-nCOV) appeared in China and precipitously extended across the globe. As always, natural disasters or infectious disease outbreaks have the potential to cause emergency department (ED) volume changes.

Objective

We aimed to assess the influence of the Coronavirus Disease 2019 (COVID-19) pandemic on ED visits and the impact on the handling of patients requiring urgent revascularization.

Methods

We reviewed the charts of all patients presenting to the ED of Hospital Sainte Anne (Toulon, France) from March 23 to April 5, 2020 and compared them with those of the same period in 2019. Then we analyzed complementary data on acute coronary syndrome (ST-elevation myocardial infarction [STEMI] and non-ST-elevation myocardial infarction [NSTEMI]) and neurovascular emergencies (strokes and transient ischemic attacks).

Results

The total number of visits decreased by 47%. The number of people assessed as triage level 2 was 8% lower in 2020. There were five fewer cases of NSTEMI in 2020, but the same number of STEMI. The number of neurovascular emergencies increased (27 cases in 2019 compared with 30 in 2020). We observed a reduction in the delay between arrival at the ED and the beginning of coronary angiography for STEMI cases (27 min in 2019 and 22 min in 2020). In 2020, 7 more stroke patients were admitted.

Conclusion

The COVID-19 pandemic probably dissuaded “non-critical” patients from coming to the hospital, whereas the same number of patients with a critical illness attended the ED as attended prior to the pandemic. There does not seem to have been any effect of the pandemic on patients requiring reperfusion therapy (STEMI and stroke).

Redefined Measure of Early Neurological Improvement Shows Treatment Benefit of Alteplase Over Placebo

Background and Purpose- The first of the 2 NINDS (National Institute of Neurological Disorders and Stroke) Study trials did not show a significant increase in early neurological improvement, defined as National Institutes of Health Stroke Scale (NIHSS) improvement by ≥4, with alteplase treatment. We hypothesized that early neurological improvement defined as a percentage change in NIHSS (percent change NIHSS) at 24 hours is superior to other definitions in predicting 3-month functional outcomes and using this definition there would be treatment benefit of alteplase over placebo at 24 hours. Methods- We analyzed the NINDS rt-PA Stroke Study (Parts 1 and 2) trial data. Percent change NIHSS was defined as ([admission NIHSS score-24-hour NIHSS score]×100/admission NIHSS score] and delta NIHSS as (admission NIHSS score-24-hour NIHSS score). We compared early neurological improvement using these definitions between alteplase versus placebo patients. We also used receiver operating characteristic curve to determine the predictive association of early neurological improvement with excellent 3-month functional outcomes (Barthel Index score of 95-100 and modified Rankin Scale score of 0-1), good 3-month functional outcome (modified Rankin Scale score of 0-2), and 3-month infarct volume. Results- There was a significantly greater improvement in the 24-hour median percent change NIHSS among patients treated with alteplase compared with the placebo group (28% versus 15%; P=0.045) but not median delta NIHSS (3 versus 2; P=0.471). Receiver operating characteristic curve comparison showed that percent change NIHSS (ROC_percent) was better than delta NIHSS (ROC_delta) and admission NIHSS (ROC_admission) with regards to excellent 3-month Barthel Index (ROC_percent, 0.83; ROC_delta, 0.76; ROC_admission, 0.75), excellent 3-month modified Rankin Scale (ROC_percent, 0.83; ROC_delta, 0.74; ROC_admission, 0.78), and good 3-month modified Rankin Scale (ROC_percent, 0.83; ROC_delta, 0.76; ROC_admission, 0.78). Conclusions- In the NINDS rt-PA trial, alteplase was associated with a significant percent change improvement in NIHSS at 24 hours. Percent change in NIHSS may be a better surrogate marker of thrombolytic activity and 3-month outcomes.

Immune Responses and Anti-inflammatory Strategies in a Clinically Relevant Model of Thromboembolic Ischemic Stroke with Reperfusion

The poor clinical relevance of experimental models of stroke contributes to the translational failure between preclinical and clinical studies testing anti-inflammatory molecules for ischemic stroke. Here, we (i) describe the time course of inflammatory responses triggered by a thromboembolic model of ischemic stroke and (ii) we examine the efficacy of two clinically tested anti-inflammatory drugs: Minocycline or anti-CD49d antibodies (tested in stroke patients as Natalizumab) administered early (1 h) or late (48 h) after stroke onset. Radiological (lesion volume) and neurological (grip test) outcomes were evaluated at 24 h and 5 days after stroke. Immune cell responses peaked 48 h after stroke onset. Myeloid cells (microglia/macrophages, dendritic cells, and neutrophils) were already increased 24 h after stroke onset, peaked at 48 h, and remained increased-although to a lesser extent-5 days after stroke onset. CD8⁺ and CD4⁺ T-lymphocytes infiltrated the ipsilateral hemisphere later on (only from 48 h). These responses occurred together with a progressive blood-brain barrier leakage at the lesion site, starting 24 h after stroke onset. Lesion volume was maximal 24-48 h after stroke onset. Minocycline reduced both lesion volume and neurological deficit only when administered early after stroke onset. The blockade of leukocyte infiltration by anti-CD49d had no impact on lesion volume or long-term neurological deficit, independently of the timing of treatment. Our data are in accordance with the results of previous clinical reports on the use of Minocycline and Natalizumab on ischemic stroke. We thus propose the use of this clinically relevant model of thromboembolic stroke with recanalization for future testing of anti-inflammatory strategies for stroke.

Effect of IV alteplase on the ischemic brain lesion at 24-48 hours after ischemic stroke

OBJECTIVE

To determine whether alteplase alters the development of ischemic lesions on brain imaging after stroke.

METHODS

The Third International Stroke Trial (IST-3) was a randomized controlled trial of IV alteplase for ischemic stroke. We assessed CT or brain MRI at baseline (pretreatment) and 24 to 48 hours posttreatment for acute lesion visibility, extent, and swelling, masked to all other data. We analyzed associations between treatment allocation, change in brain tissue appearances between baseline and follow-up imaging, and 6-month functional outcome in IST-3. We performed a meta-analysis of randomized trials of alteplase vs control with pre- and postrandomization imaging.

RESULTS

Of 3,035 patients recruited in IST-3, 2,916 had baseline and follow-up brain imaging. Progression in either lesion extent or swelling independently predicted poorer 6-month outcome (adjusted odds ratio [OR] = 0.92, 95% confidence interval [CI] 0.88-0.96, p < 0.001; OR = 0.73, 95% CI 0.66-0.79, p < 0.001, respectively). Patients allocated alteplase were less likely than controls to develop increased lesion visibility at follow-up (OR = 0.77, 95% CI 0.67-0.89, p < 0.001), but there was no evidence that alteplase reduced progression of lesion extent or swelling. In meta-analysis of 6 trials including IST-3 (n = 4,757), allocation to alteplase was associated with a reduction in ischemic lesion extent on follow-up imaging (OR = 0.85, 95% CI 0.76-0.95, p = 0.004).

CONCLUSION

Alteplase was associated with reduced short-term progression in lesion visibility. In meta-analysis, alteplase reduced lesion extent. These findings may indicate that alteplase improves functional outcome by reducing tissue damage.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that IV alteplase impedes the progression of ischemic brain lesions on imaging after stroke.

Altered levels of circulating insulin-like growth factor I (IGF-I) following ischemic stroke are associated with outcome - a prospective observational study

Background

Insulin-like growth factor I (IGF-I) has neuroprotective effects in experimental ischemic stroke (IS). However, in patients who have suffered IS, various associations between the levels of serum IGF-I (s-IGF-I) and clinical outcome have been reported, probably reflecting differences in sampling time-points and follow-up periods. Since changes in the levels of post-stroke s-IGF-I have not been extensively explored, we investigated whether decreases in the levels of s-IGF-I between the acute time-point (median, 4 days) and 3 months (ΔIGF-I, further transformed into ΔIGF-I-quintiles, ΔIGF-I-q) are associated with IS severity and outcome.

Methods

In the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS) conducted in Gothenburg, Sweden, patients with IS who had s-IGF-I measurements available were included (N = 354; 65% males; mean age, 55 years). Baseline stroke severity was evaluated using the National Institutes of Health Stroke Scale (NIHSS) and converted into NIHSS-quintiles (NIHSS-q). Outcomes were assessed using the modified Rankin Scale (mRS) at 3 months and 2 years.

Results

In general, the levels of s-IGF-I decreased (positive ΔIGF-I), except for those patients with the most severe NIHSS-q. After correction for sex and age, the 3rd ΔIGF-I-q showed the strongest association to mRS 0–2 [Odds Ratio (OR) 5.11, 95% confidence interval (CI) 2.18–11.9], and after 2 years, the 5th ΔIGF-I-q (OR 3.63, 95% CI 1.40–9.38) showed the strongest association to mRS 0–2. The associations remained significant after multivariate correction for diabetes, smoking, hypertension, and hyperlipidemia after 3 months, but were not significant (p = 0.057) after 2 years. The 3-month associations withstood additional correction for baseline stroke severity (p = 0.035), whereas the 2-year associations were further attenuated (p = 0.31).

Conclusions

Changes in the levels of s-IGF-I are associated primarily with temporally near 3-month outcomes, while associations with long-term 2-year outcomes are weakened and attenuated by other factors. The significance of the change in post-stroke s-IGF-I is compatible with a positive role for IGF-I in IS recovery. However, the exact mechanisms are unknown and probably reflects combinations of multiple peripheral and central actions.

Electronic supplementary material

The online version of this article (10.1186/s12883-018-1107-3) contains supplementary material, which is available to authorized users.

MicroRNA-126 Priming Enhances Functions of Endothelial Progenitor Cells under Physiological and Hypoxic Conditions and Their Therapeutic Efficacy in Cerebral Ischemic Damage

Endothelial progenitor cells (EPCs) have shown the potential for treating ischemic stroke (IS), while microRNA-126 (miR-126) is reported to have beneficial effects on endothelial function and angiogenesis. In this study, we investigated the effects of miR-126 overexpression on EPCs and explore the efficacy of miR-126-primed EPCs (EPC^miR-126) in treating IS. The effects of miR-126 overexpression on EPC proliferation, migratory, tube formation capacity, reactive oxygen species (ROS) production, and nitric oxide (NO) generation were determined. In in vivo study, the effects of EPC^miR-126 on the cerebral blood flow (CBF), neurological deficit score (NDS), infarct volume, cerebral microvascular density (cMVD), and angiogenesis were determined. Moreover, the levels of circulating EPCs (cEPCs) and their contained miR-126 were measured. We found (1) miR-126 overexpression promoted the proliferation, migration, and tube formation abilities of EPCs; decreased ROS; and increased NO production of EPCs via activation of PI3K/Akt/eNOS pathway; (2) EPC^miR-126 was more effective than EPCs in attenuating infarct volume and NDS and enhancing cMVD, CBF, and angiogenesis; and (3) infusion of EPC^miR-126 increased the number and the level of miR-126 in cEPCs. Our data indicate that miR-126 overexpression enhanced the function of EPCs in vitro and in vivo.

New Pathways for Evaluating Potential Acute Stroke Therapies

Pharmacological therapy for acute ischemic stroke remains limited to one successful, approved treatment: tissue plasminogen activator within 3 h of stroke onset. Many neuroprotective drugs and a few other thrombolytics were evaluated in clinical trials, but none demonstrated unequivocal success and were approved by regulatory agencies. The development paradigm for such therapies needs to provide convincing evidence of efficacy and safety to obtain approval by the Food and Drug Administration (FDA). The FDA modernization act of 1997 stated that such evidence could be derived from one large phase III trial with a clinical endpoint and supportive evidence. Drugs being developed for acute ischemic stroke can potentially be approved under this act by coupling a major phase III trial with supportive evidence provided by a phase IIB trial demonstrating an effect on a relevant biomarker such as magnetic resonance imaging or computed tomography assessment of ischemic lesion growth. Statistical approaches have been developed to optimize the design of such an imaging-based phase IIB study, for example approaches that modify randomization probabilities to assign larger proportions of patients to the ‘winning’ strategy (i.e. ‘pick the winner’ strategies) with an interim assessment to reduce the sample size requirement. Demonstrating a treatment effect on a relevant imaging-based biomarker should provide supportive evidence for a new drug application, if a subsequent phase III trial with a clinical outcome demonstrates a significant treatment effect.

Neuroprotective Strategies after Neonatal Hypoxic Ischemic Encephalopathy

Neonatal hypoxic ischemic encephalopathy (HIE) is a devastating disease that primarily causes neuronal and white matter injury and is among the leading cause of death among infants. Currently there are no well-established treatments; thus, it is important to understand the pathophysiology of the disease and elucidate complications that are creating a gap between basic science and clinical translation. In the development of neuroprotective strategies and translation of experimental results in HIE, there are many limitations and challenges to master based on an appropriate study design, drug delivery properties, dosage, and use in neonates. We will identify understudied targets after HIE, as well as neuroprotective molecules that bring hope to future treatments such as melatonin, topiramate, xenon, interferon-beta, stem cell transplantation. This review will also discuss some of the most recent trials being conducted in the clinical setting and evaluate what directions are needed in the future.

Why don't more patients receive intravenous rt-PA for acute stroke?

Intravenous rt-PA was proven safe and effective for acute ischemic stroke in 1995, approved by US FDA in 1996, and endorsed by the American Heart Association, American Academy of Neurology, and National Stroke Association in 1997. The treatment is remarkably cost-effective, despite the high cost of the drug itself and the stroke teams to give it. Community-based practicing neurologists can use t-PA for acute stroke without the need for specialized expertise. The benefit is durable over long-term follow-up and no particular subgroups, such as the elderly or those with very large strokes, should be excluded from treatment. Several additional studies have now confirmed the beneficial effects of thrombolytic therapy for stroke in de novo samples. So why isn't the drug used more? Some troubling mis-understandings in the literature seem persistent and influential among clinicians. Considerable data supports the use of rt-PA for acute ischemic stroke, which should remove remaining doubts.

Initial body temperature in ischemic stroke: nonpotentiation of tissue-type plasminogen activator benefit and inverse association with severity

BACKGROUND AND PURPOSE

Body temperature (BT) is an important physiological factor in acute ischemic stroke. However, the relationship of initial BT to stroke severity and degree of benefit from thrombolytic therapy has been delineated incompletely.

METHODS

We analyzed the public data set of the 2 National Institute of Neurological Disorders and Stroke Tissue-Type Plasminogen Activator (tPA) stroke trials, comparing patients with lower (<37.0°C) and higher (≥37.0°C) presenting BT.

RESULTS

Among 595 patients (297 placebo and 298 tPA treated) with documented initial BT, 77.1% had initial BT <37.0°C and 22.9% ≥37.0°C. Patients with higher initial BT had lower baseline stroke severity in both tPA-treated patients (the National Institute of Health Stroke Scale median, 11 versus 15; P=0.05) and placebo-treated patients (median, 13 versus 16; P<0.01). Patients with higher initial BT also had lower infarction volume on computed tomography at 3 months in both tPA-treated patients (median, 9.6 versus 16.7 cm(3); P=0.08) and placebo-treated patients (median, 13.1 versus 28.1 cm(3); P=0.02), but no clinical outcome differences. Analysis of lytic treatment effect found no heterogeneity in the degree of tPA benefit in both higher and lower BT groups (≥37.0°C: odds ratio for the modified Rankin Scale 0-1 outcome, 2.55; 95% confidence interval, 1.05-6.21 and <37.0°C: odds ratio, 2.30; 95% confidence interval, 1.38-3.84; heterogeneity P=0.83).

CONCLUSIONS

In patients with hyperacute stroke, higher presenting temperatures are associated with less severe neurological deficits and reduced final infarct volumes. Presenting temperature does not modify the benefit of tPA on 3-month favorable outcome.

Modeling stroke in mice: permanent coagulation of the distal middle cerebral artery

Stroke is the third most common cause of death and a main cause of acquired adult disability in developed countries. Only very limited therapeutical options are available for a small proportion of stroke patients in the acute phase. Current research is intensively searching for novel therapeutic strategies and is increasingly focusing on the sub-acute and chronic phase after stroke because more patients might be eligible for therapeutic interventions in a prolonged time window. These delayed mechanisms include important pathophysiological pathways such as post-stroke inflammation, angiogenesis, neuronal plasticity and regeneration. In order to analyze these mechanisms and to subsequently evaluate novel drug targets, experimental stroke models with clinical relevance, low mortality and high reproducibility are sought after. Moreover, mice are the smallest mammals in which a focal stroke lesion can be induced and for which a broad spectrum of transgenic models are available. Therefore, we describe here the mouse model of transcranial, permanent coagulation of the middle cerebral artery via electrocoagulation distal of the lenticulostriatal arteries, the so-called “coagulation model”. The resulting infarct in this model is located mainly in the cortex; the relative infarct volume in relation to brain size corresponds to the majority of human strokes. Moreover, the model fulfills the above-mentioned criteria of reproducibility and low mortality. In this video we demonstrate the surgical methods of stroke induction in the “coagulation model” and report histological and functional analysis tools.

Thrombolysis for acute ischaemic stroke

BACKGROUND

Most strokes are due to blockage of an artery in the brain by a blood clot. Prompt treatment with thrombolytic drugs can restore blood flow before major brain damage has occurred and improve recovery after stroke in some people. Thrombolytic drugs, however, can also cause serious bleeding in the brain, which can be fatal. One drug, recombinant tissue plasminogen activator (rt-PA), is licensed for use in selected patients within 4.5 hours of stroke in Europe and within three hours in the USA. There is an upper age limit of 80 years in some countries, and a limitation to mainly non-severe stroke in others. Forty per cent more data are available since this review was last updated in 2009.

OBJECTIVES

To determine whether, and in what circumstances, thrombolytic therapy might be an effective and safe treatment for acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched November 2013), MEDLINE (1966 to November 2013) and EMBASE (1980 to November 2013). We also handsearched conference proceedings and journals, searched reference lists and contacted pharmaceutical companies and trialists.

SELECTION CRITERIA

Randomised trials of any thrombolytic agent compared with control in people with definite ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors applied the inclusion criteria, extracted data and assessed trial quality. We verified the extracted data with investigators of all major trials, obtaining additional unpublished data if available.

MAIN RESULTS

We included 27 trials, involving 10,187 participants, testing urokinase, streptokinase, rt-PA, recombinant pro-urokinase or desmoteplase. Four trials used intra-arterial administration, while the rest used the intravenous route. Most data come from trials that started treatment up to six hours after stroke. About 44% of the trials (about 70% of the participants) were testing intravenous rt-PA. In earlier studies very few of the participants (0.5%) were aged over 80 years; in this update, 16% of participants are over 80 years of age due to the inclusion of IST-3 (53% of participants in this trial were aged over 80 years). Trials published more recently utilised computerised randomisation, so there are less likely to be baseline imbalances than in previous versions of the review. More than 50% of trials fulfilled criteria for high-grade concealment; there were few losses to follow-up for the main outcomes.Thrombolytic therapy, mostly administered up to six hours after ischaemic stroke, significantly reduced the proportion of participants who were dead or dependent (modified Rankin 3 to 6) at three to six months after stroke (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.78 to 0.93). Thrombolytic therapy increased the risk of symptomatic intracranial haemorrhage (OR 3.75, 95% CI 3.11 to 4.51), early death (OR 1.69, 95% CI 1.44 to 1.98; 13 trials, 7458 participants) and death by three to six months after stroke (OR 1.18, 95% CI 1.06 to 1.30). Early death after thrombolysis was mostly attributable to intracranial haemorrhage. Treatment within three hours of stroke was more effective in reducing death or dependency (OR 0.66, 95% CI 0.56 to 0.79) without any increase in death (OR 0.99, 95% CI 0.82 to 1.21; 11 trials, 2187 participants). There was heterogeneity between the trials. Contemporaneous antithrombotic drugs increased the risk of death. Trials testing rt-PA showed a significant reduction in death or dependency with treatment up to six hours (OR 0.84, 95% CI 0.77 to 0.93, P = 0.0006; 8 trials, 6729 participants) with significant heterogeneity; treatment within three hours was more beneficial (OR 0.65, 95% CI 0.54 to 0.80, P < 0.0001; 6 trials, 1779 participants) without heterogeneity. Participants aged over 80 years benefited equally to those aged under 80 years, particularly if treated within three hours of stroke.

AUTHORS' CONCLUSIONS

Thrombolytic therapy given up to six hours after stroke reduces the proportion of dead or dependent people. Those treated within the first three hours derive substantially more benefit than with later treatment. This overall benefit was apparent despite an increase in symptomatic intracranial haemorrhage, deaths at seven to 10 days, and deaths at final follow-up (except for trials testing rt-PA, which had no effect on death at final follow-up). Further trials are needed to identify the latest time window, whether people with mild stroke benefit from thrombolysis, to find ways of reducing symptomatic intracranial haemorrhage and deaths, and to identify the environment in which thrombolysis may best be given in routine practice.

Desmoteplase in the treatment of acute ischemic stroke

Desmoteplase, developed by Paion, Forest and Lundbeck, is a novel plasminogen activator that selectively activates fibrin-bound plasminogen and is currently being investigated for the treatment of acute ischemic stroke within the time window of 3-9 h after symptom onset. Desmoteplase is believed to offer pharmacologic advantages over currently approved treatment options. To date, two published Phase II perfusion imaging-based clinical trials have reported the safety and potential efficacy of desmoteplase in ischemic stroke. Results from a recently completed Phase III trial in Europe, Asia and the USA are awaited. This article reviews the available data on desmoteplase, including discussion of its favorable features and potential benefit beyond the 3-h time window in the treatment of ischemic stroke.

Clinical-radiological severity mismatch phenomenon: patients with severe neurological deficits without matching infarction on computed tomographic scan

OBJECTIVE

The objective was to determine the long-term outcome of patients with severe persistent neurological deficits without a large infarction on computed tomographic (CT) scan.

METHODS

We analyzed the prospectively collected data as part of the randomized, placebo controlled trial in patients with ischemic stroke presenting within 3 hours of symptom onset. Volume of infarction was measured from CT scan acquired at 3 months. Favorable outcome defined by no significant or slight disability on a modified Rankin scale at 12 months. We determined the outcome of patients with National Institutes of Health Stroke Scale score (NIHSS score) ≥ 10 at 24 hours.

RESULTS

Of the 277 patients with NIHSS score ≥ 10 at 24 hours, 88 (32%) met the criteria of clinical-radiological severity mismatch. Compared with patients with NIHSS score ≥ 10 with infarct volume ≥ 20 cc, the patients with NIHSS score ≥ 10 and infarct volume <20 cc were older but there were no differences in the gender, race or vascular risk factors. Patients with clinical-radiological severity mismatch were more likely to have a favorable outcome at 12 months compared with those without mismatch (odd ratio 4.3, 95% confidence interval 1.5-12.6, P = .0063) after adjusting for potential confounders.

CONCLUSIONS

We observed that approximately one-fourth of patients with severe neurological deficits have clinical-radiological severity mismatch. Such patients appear to have a high rate of favorable outcomes at 1 year.

Association of a higher density of specialist neuroscience providers with fewer deaths from stroke in the United States population

OBJECT

Stroke is a leading cause of death and disability. Given that neurologists and neurosurgeons have special expertise in this area, the authors hypothesized that the density of neuroscience providers is associated with reduced mortality rates from stroke across US counties.

METHODS

This is a retrospective review of the Area Resource File 2009-2010, a national county-level health information database maintained by the US Department of Health and Human Services. The primary outcome variable was the 3-year (2004-2006) average in cerebrovascular disease deaths per million population for each county. The primary independent variable was the combined density of neurosurgeons and neurologists per million population in the year 2006. Multiple regression analysis was performed, adjusting for density of general practitioners (GPs), urbanicity of the county, and socioeconomic status of the residents of the county.

RESULTS

In the 3141 counties analyzed, the median number of annual stroke deaths was 586 (interquartile range [IQR] 449-754), the median number of neuroscience providers was 0 (IQR 0-26), and the median number of GPs was 274 (IQR 175-410) per million population. On multivariate adjusted analysis, each increase of 1 neuroscience provider was associated with 0.38 fewer deaths from stroke per year (p < 0.001) per million population. Rural location (p < 0.001) and increased density of GPs (p < 0.001) were associated with increases in stroke-related mortality.

CONCLUSIONS

Higher density of specialist neuroscience providers is associated with fewer deaths from stroke. This suggests that the availability of specialists is an important factor in survival after stroke, and underlines the importance of promoting specialist education and practice throughout the country.

Menstrual blood transplantation for ischemic stroke: Therapeutic mechanisms and practical issues

Cerebrovascular diseases are a major cause of death and long-term disability in developed countries. Tissue plasmin activator (tPA) is the only approved therapy for ischemic stroke, strongly limited by the short therapeutic window and hemorrhagic complications, therefore excluding most patients from its benefits. The rescue of the penumbra area of the ischemic infarct is decisive for functional recovery after stroke. Inflammation is a key feature in the penumbra area and it plays a dual role, improving injury in early phases but impairing neural survival at later stages. Stem cells can be opportunely used to modulate inflammation, abrogate cell death and, therefore, preserve neural function. We here discuss the possible role of stem cells derived from menstrual blood as restorative treatment for stroke. We highlight the availability, proliferative capacity, pluripotentiality and angiogenic features of these cells and explore their present and future experimental and clinical applications.

Interobserver reliability of baseline noncontrast CT Alberta Stroke Program Early CT Score for intra-arterial stroke treatment selection

BACKGROUND AND PURPOSE

Early ischemic changes on pretreatment NCCT quantified using ASPECTS have been demonstrated to predict outcomes after IAT. We sought to determine the interobserver reliability of ASPECTS for patients with AIS with PAO and to determine whether pretreatment ASPECTS dichotomized at 7 would demonstrate at least substantial κ agreement.

MATERIALS AND METHODS

From our prospective IAT data base, we identified consecutive patients with anterior circulation PAO who underwent IAT over a 6-year period. Only those with an evaluable pretreatment NCCT were included. ASPECTS was graded independently by 2 experienced readers. Interrater agreement was assessed for total ASPECTS, dichotomized ASPECTS (≤ 7 versus >7), and each ASPECTS region. Statistical analysis included determination of Cohen κ coefficients and concordance correlation coefficients. PABAK coefficients were also calculated.

RESULTS

One hundred fifty-five patients met our study criteria. Median pretreatment ASPECTS was 8 (interquartile range 7-9). Interrater agreement for total ASPECTS was substantial (concordance correlation coefficient = 0.77). The mean ASPECTS difference between readers was 0.2 (95% confidence interval, -2.8 to 2.4). For dichotomized ASPECTS, there was a 76.8% (119/155) observed rate of agreement, with a moderate κ = 0.53 (PABAK = 0.54). By region, agreement was worst in the internal capsule and the cortical areas, ranging from fair to moderate. After adjusting for prevalence and bias, agreement improved to substantial or near perfect in most regions.

CONCLUSIONS

Interobserver reliability is substantial for total ASPECTS but is only moderate for ASPECTS dichotomized at 7. This may limit the utility of dichotomized ASPECTS for IAT selection.

Wake-up stroke within 3 hours of symptom awareness: imaging and clinical features compared to standard recombinant tissue plasminogen activator treated stroke

BACKGROUND

Patients with wake-up stroke (WUS) are excluded from thrombolysis because of unknown time of symptom onset. Previous studies have reported similar stroke severity and early ischemic changes (EICs) in patients with WUS and stroke of known onset. These studies, however, included patients within a large timeframe to imaging or did not quantify EICs. The aim of our study was to quantify EICs of patients with WUS presenting within 3 hours of symptom recognition compared to standard 3-hours recombinant tissue plasminogen activator (rt-PA)-treated patients and assess the extent of ischemic lesion and functional independence at follow-up.

METHODS

Patients were selected from our prospectively collected stroke database. Baseline and follow-up computed tomographic scans were graded with Alberta Stroke Program Early Computed Tomography Score (ASPECTS). Clinical outcome measures were modified Rankin Scale score, mortality, and symptomatic intracerebral hemorrhage.

RESULTS

Demographic features, risk factors, stroke severity, and baseline ASPECTS were similar in both groups. WUS and rt-PA-treated patients had similar tissue outcome (median ASPECTS 7.0 vs 7.5; P = .202). Functional outcome was more favorable in rt-PA-treated patients (61.6% vs 43.1%; odds ratio [OR] 2.12; 95% confidence interval [CI] 1.05-4.28; P = .037). After adjusting for age, stroke severity, treatment, and EICs in less than one-third of middle cerebral artery territory, rt-PA and National Institutes of Health Stroke Scale scores remained the only significant predictors of outcome (OR 7.76; 95% CI 2.40-25.05; P = .001 and OR 0.74; 95% CI 0.67-0.82; P < .001, respectively).

CONCLUSIONS

Within 3 hours of symptom recognition, patients with WUS have EICs similar to rt-PA-treated patients. It is reasonable to expect that selected WUS patients might benefit from thrombolysis within 3 hours of symptom awareness.

Predictive role of modified clinical diffusion mismatch in early neurological deterioration due to atherothrombotic ischemia in the anterior circulation

BACKGROUND

Atherothrombotic ischemia is the most frequent cause of cerebral ischemia; however, few reports have addressed the prognostic factors predicting early neurological deterioration (END) when the occlusive lesion is limited to the anterior main trunk, middle cerebral artery (MCA) or internal cerebral artery (ICA).

METHOD

Between 2006 and 2008, 122 atherothrombotic ischemia patients were diagnosed with MCA or ICA occlusive disease on magnetic resonance angiography. The National Institutes of Health Stroke Scale (NIHSS) score and the modified Alberta Stroke Program Early CT Score on diffusion-weighted imaging [ASPECTS-DW (modified)] were calculated. Clinical-DWI mismatch (CDM) was evaluated using NIHSS and the ASPECTS-DW (modified) to examine the predictive efficacy for early neurological deterioration.

RESULTS

Eighteen of 122 (14.8%) patients fulfilled the definition of CDM. END was observed in 24 patients (19.7%) within 15 days after admission. CDM was observed in 14 cases in the END (+) group (14 of 24 cases, 58.3%) and 4 cases in the END (-) group (4 of 98 cases, 4.1%) (p = 0.001). Multivariate logistic regression analysis demonstrated that CDM was a significant predictive factor of END (odds ratio 26.68, p = 0.0001).

CONCLUSIONS

CDM based on NIHSS and ASPECTS-DW (modified) could be a significant predictive factor for END of atherothrombotic ischemia in MCA/ICA.

Application of beta regression to analyze ischemic stroke volume in NINDS rt-PA clinical trials

BACKGROUND AND PURPOSE

Ischemic stroke lesion volumes have proven difficult to analyze due to the extremely skewed shape of their underlying distribution. We introduce an extension of generalized linear models, beta regression, as a possible method of modeling extremely skewed distributions as evidenced in ischemic stroke lesion volumes.

METHODS

The NINDS rt-PA clinical trials measured ischemic stroke lesion volume as a secondary trial outcome. Three-month lesion volumes from these trials were analyzed using beta regression. A multi-variable regression model associating explanatory variables with ischemic stroke lesion volumes was constructed using accepted model building strategies and compared with the previously published volumetric analysis.

RESULTS

Beta regression produced a similar model when compared to the previous analysis published by the study group. All previously identified variables of importance were detected in the model building process. The age by treatment interaction described in previous studies was also found in this analysis, confirming the strong effect age has on stroke outcomes. Further, a treatment effect was elicited in terms of odds ratios, yielding a previously unknown quantification of the effect of rt-PA on lesion volumes.

CONCLUSIONS

Beta regression proved adept in modeling ischemic stroke lesions and offered the interpretation of covariates in terms of odds ratios. Beta regression is seen as a legitimate alternative to analyze ischemic stroke volumes.

Methodological issues in monitoring health services and outcomes for stroke survivors: a case study

BACKGROUND

Obtaining comprehensive health outcomes and health services utilization data on stroke patients has been difficult. This research grew out of a memorandum of understanding between the NIH and the ISS (its Italian equivalent) to foster collaborative research on rehabilitation.

OBJECTIVE

The purpose of this study was to pilot a methodology using administrative data to monitor and improve health outcomes for stroke survivors in Tuscany.

METHODS

This study used qualitative and quantitative methods to study health resources available to and utilized by stroke survivors during the first 12 months post-stroke in two Italian health authorities (AUSL10 and 11). Mortality rates were used as an outcome measure.

RESULTS

Number of inpatient days, number of prescriptions, and prescription costs were significantly higher for patients in AUSL 10 compared to AUSL 11. There was no significant difference between mortality rates.

CONCLUSION

Using administrative data to monitor process and outcomes for chronic stroke has the potential to save money and improve outcomes. However, measures of functional impairment and more sensitive outcome measures than mortality are important. Additional recommendations for enhanced data collection and reporting are discussed.

Neurocritical care for neonates

BACKGROUND

To describe the concept, implementation, patient characteristics, and preliminary outcomes of a Neonatal Neurocritical Care Service (NNCS) recently established at the University of California, San Francisco.

METHODS

The NNCS was developed to better address the special needs of neonates at risk for neurological injury. The service combines dedicated neurological care, specialized neonatal medical and nursing expertise, neuromonitoring, neuroimaging, neurodevelopmental care, and long-term follow up. Newborns evaluated by the NNCS between July 2008 and June 2009 were included in the analysis. Demographic data (gestational age at birth, sex, admission diagnosis, and reason for consult), outcome (mortality, length of stay), and neurophysiology and imaging resources were extracted from patient charts.

RESULTS

Over the 12-month period, 155 newborns were evaluated (approximately 25% of all admissions); of these, 51 were preterm (<36 weeks gestation) and 104 were term. Approximately half were admitted for primary medical diagnoses, such as preterm birth, congenital malformations or apnea/apparent life-threatening event (ALTE), with the remainder admitted for primary neurological problems, including perinatal asphyxia, seizures/possible seizures, or congenital cerebral malformation. The most common neurological diagnoses were hypoxic-ischemic encephalopathy (38%) and seizure (35%). Among preterm newborns, intraventricular hemorrhage grade III and periventricular hemorrhagic infarction were most common. Mortality was approximately 20% in both preterm and term populations.

CONCLUSIONS

While specialized neurocritical care has improved outcomes in adult populations, longitudinal studies are needed to determine whether specialized neurocritical care services will also result in improved neurodevelopmental outcomes for newborns.

Can animal models of disease reliably inform human studies?

H. Bart van der Worp and colleagues discuss the controversies and possibilities of translating the results of animal experiments into human clinical trials.

Thrombolysis for acute ischaemic stroke

BACKGROUND

The majority of strokes are due to blockage of an artery in the brain by a blood clot. Prompt treatment with thrombolytic drugs can restore blood flow before major brain damage has occurred and could improve recovery after stroke. Thrombolytic drugs, however, can also cause serious bleeding in the brain, which can be fatal. One drug, recombinant tissue plasminogen activator (rt-PA), is licensed for use in highly selected patients within three hours of stroke.

OBJECTIVES

To assess the safety and efficacy of thrombolytic agents in patients with acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched October 2008), MEDLINE (1966 to October 2008) and EMBASE (1980 to October 2008). We contacted researchers and pharmaceutical companies, attended relevant conferences and handsearched pertinent journals.

SELECTION CRITERIA

Randomised trials of any thrombolytic agent compared with control in patients with definite ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors applied the inclusion criteria and extracted data. We assessed trial quality. We verified the extracted data with the principal investigators of all major trials. We obtained both published and unpublished data if available.

MAIN RESULTS

We included 26 trials involving 7152 patients. Not all trials contributed data to each outcome. The trials tested urokinase, streptokinase, recombinant tissue plasminogen activator, recombinant pro-urokinase or desmoteplase. Four trials used intra-arterial administration, the rest used the intravenous route. Most data come from trials that started treatment up to six hours after stroke; three trials started treatment up to nine hours and one small trial up to 24 hours after stroke. About 55% of the data (patients and trials) come from trials testing intravenous tissue plasminogen activator. Very few of the patients (0.5%) were aged over 80 years. Many trials had some imbalances in key prognostic variables. Several trials did not have complete blinding of outcome assessment. Thrombolytic therapy, mostly administered up to six hours after ischaemic stroke, significantly reduced the proportion of patients who were dead or dependent (modified Rankin 3 to 6) at three to six months after stroke (odds ratio (OR) 0.81, 95% confidence interval (CI) 0.73 to 0.90). Thrombolytic therapy increased the risk of symptomatic intracranial haemorrhage (OR 3.49, 95% CI 2.81 to 4.33) and death by three to six months after stroke (OR 1.31, 95% CI 1.14 to 1.50). Treatment within three hours of stroke appeared more effective in reducing death or dependency (OR 0.71, 95% CI 0.52 to 0.96) with no statistically significant adverse effect on death (OR 1.13, 95% CI 0.86 to 1.48). There was heterogeneity between the trials in part attributable to concomitant antithrombotic drug use (P = 0.02), stroke severity and time to treatment. Antithrombotic drugs given soon after thrombolysis may increase the risk of death.

AUTHORS' CONCLUSIONS

Overall, thrombolytic therapy appears to result in a significant net reduction in the proportion of patients dead or dependent in activities of daily living. This overall benefit was apparent despite an increase both in deaths (evident at seven to 10 days and at final follow up) and in symptomatic intracranial haemorrhages. Further trials are needed to identify which patients are most likely to benefit from treatment and the environment in which thrombolysis may best be given in routine practice.

Clinical outcomes of acute stroke patients with atrial fibrillation

Evaluation of: Kazumi K, Yasuyuki I, Kensaku S, Takeshi I, Shinji Y, Junya A. IV-tPA therapy in acute stroke patients with atrial fibrillation. J. Neurol. Sci. 276(1-2), 6-8 (2009). Stroke is the leading cause of disability and the second most common cause of death worldwide. The care and treatment of stroke patients have evolved over the last two decades, with increasing use of thrombolysis (e.g., intravenous tissue plasminogen activator in acute stroke patients), which has improved survival and recovery following stroke. The article under evaluation offers a greater insight into the relationship of clinical outcome of stroke and atrial fibrillation after tissue plasminogen activator infusion.

Differential patterns of evolution in acute middle cerebral artery infarction with perfusion-diffusion mismatch: atherosclerotic vs. cardioembolic occlusion

BACKGROUND

An acute perfusion-diffusion mismatch is known to be the strongest predictor of infarct growth. However, the differential patterns of clinical and radiological evolution according to stroke mechanism are unknown.

METHODS

The study retrospectively reviewed consecutive patients who had 1) acute middle cerebral artery (MCA) territory infarction, 2) diffusion- and perfusion-weighted imaging (DWI and PWI) and MR angiography within 24 h of onset, and follow-up DWI 5 days later, 3) stenosis (> or =50%) or occlusion of MCA on baseline imaging, 4) a baseline PWI-DWI mismatch >20%, and 5) either atherosclerotic MCA disease (MCAD) or cardioembolism (CE). National Institutes of Health Stroke Scale (NIHSS) scores and infarct volume at baseline and 5 days were obtained.

RESULTS

Of 90 patients, 52 had MCAD and 38 had CE. At baseline, CE group had more severe stroke (median NIHSS, 9 vs. 5; p=0.001) and larger infarct volume (median 8.32 cc vs. 3.0 cc; p=0.034) than MCAD group. During the 1-week period, CE group had larger infarct volume growth (median 12.85 cc vs. 3.02 cc; p=0.004) than MCAD group, although clinical improvement based on NIHSS (baseline minus 5-day) tended to be higher for CE than MCAD group (median 3 vs. 1; p=0.08). The correlation between infarct volume and NIHSS score was stronger in CE (r=0.841) compared to MCAD (r=0.582) group at 5-day.

CONCLUSIONS

Substantial differences in the clinico-radiological evolution of acute ischemic stroke exist according to stroke mechanism. These data emphasize the importance of the stroke mechanism in the design of MRI-based acute stroke trials.

A user's guide to the NINDS rt-PA stroke trial database

Robert Dachs and colleagues describe the process for researchers to acquire and decipher the dataset from the original NINDS rt-PA trial.

Intravenous recombinant tissue plasminogen activator improves arterial recanalization rates and reduces infarct volumes in patients with hyperdense artery sign on baseline computed tomography

BACKGROUND

We sought to evaluate arterial recanalization as measured by changes in the presence of hyperdense artery sign (HAS) on initial and 24-hour computed tomography scans in patients treated with recombinant tissue plasminogen activator (rt-PA) or placebo, and to assess the effect of rt-PA on patient outcomes in this population.

METHODS

Patients in the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Trial composed the study group. We determined the percentage of patients with HAS in rt-PA- and placebo-treated groups who had persistence (HAS +/+) or resolution (HAS +/-) of HAS on 24-hour computed tomography, and compared outcomes in those with resolution or persistence of the sign in these treatment groups.

RESULTS

Baseline HAS occurred in 79 of 604 eligible patients (13%). The two treatment groups were similar, although patients treated with rt-PA were significantly older. Of the 79 patients with HAS on baseline computed tomography scan, 14 of 37 (38%) treated with rt-PA had resolution of HAS at 24 hours compared with 7 of 42 (17%) treated with placebo (P = .03). Infarct volumes at 24 hours were significantly smaller in patients treated with rt-PA with resolution of the sign, compared with those who had persistence of the sign (P = .004). In our analysis, functional outcomes were not significantly improved based on resolution of HAS in either treatment group. There were 4 symptomatic ICHs in the rt-PA-treated group with HAS as compared with two in the placebo-treated group.

CONCLUSION

Among patients with HAS at baseline in the NINDS rt-PA Stroke Trial, intravenous rt-PA increased recanalization as measured by resolution of HAS and reduced infarct volumes at 24 hours.

Reperfusion enhances nitrotyrosine formation in rat focal cerebral ischemia

The widespread benefit of thrombolysis has been emphasized, but relatively little is known about reperfusion injury. The purpose of this study is to evaluate the difference in nitrotyrosine formation and infarct volume between permanent and transient focal ischemia in rats. Permanent (n = 14) or transient (n = 12) focal ischemia was induced by permanent or 2-hour occlusion of the middle cerebral artery, respectively, with the permanent ligation of the bilateral common carotid arteries in Sprague-Dawley rats. In both models all animals were killed 24 hours after the start of occlusion. The ratio of nitrotyrosine in the peri-infarct and core-of-infarct regions in transient focal ischemia was significantly higher than in permanent focal ischemia (P < .01). Infarct volume in the cortex, but not caudoputamen or whole brain, was significantly larger in transient ischemia than in permanent ischemia (P < .05), with a significant expansion of brain swelling. These results may reflect the higher production of superoxide and nitric oxide owing to reperfusion, and suggest the need to administer neuroprotective drugs such as anti-oxidants as well as thrombolytic agents in the treatment of acute ischemic cerebral damage.

Brain stimulation in poststroke rehabilitation

Brain stimulation techniques provide a powerful means to modulate the function of specific neural structures, and show potential for future applications in the rehabilitation of stroke patients. Recent studies have started to translate to the bedside the body of data gathered over the last few years on mechanisms underlying brain plasticity and stroke recovery. Both noninvasive and invasive brain stimulation techniques, such as repetitive transcranial magnetic stimulation, transcranial direct current stimulation and direct cortical stimulation with epidural electrodes, have recently been tested in small studies with stroke patients. The results to date are very promising. Nonetheless, we are still at an early stage in the field and further evidence is needed to assess the clinical impact of this new approach. In this review, we provide readers with a basic introduction to the field, summarize preliminary studies and discuss future directions.

Clinical-diffusion mismatch defined by NIHSS and ASPECTS in non-lacunar anterior circulation infarction

OBJECTIVES

Instead of the mismatch in MRI between the perfusion-weighted imaging (PWI) lesion and the smaller diffusion-weighted imaging (DWI) lesion (PWI-DWI mismatch), clinical-DWI mismatch (CDM) has been proposed as a new diagnostic marker of brain tissue at risk of infarction in acute ischemic stroke. The Alberta Stroke Program Early CT Score (ASPECTS) has recently been applied to detect early ischemic change of acute ischemic stroke. The present study applies the CDM concept to DWI data and investigated the utility of the CDM defined by the NIH Stroke Scale (NIHSS) and ASPECTS in patients with non-lacunar anterior circulation infarction.

METHODS

Eighty-seven patients with first ever ischemic stroke within 24 hours of onset with symptoms of non-lacunar anterior circulation infarction with the NIHSS score>or=8 were enrolled. Initial lesion extent was measured by the ASPECTS on DWI within 24 hours, and initial neurological score was measured by the NIHSS. As NIHSS>or=8 has been suggested as a clinical indicator of a large volume of ischemic brain tissue, and the majority of patients with non-lacunar anterior infarction with score of NIHSS<8 had lesions with ASPECTS>or=8 on DWI, so CDM was defined as NIHSS>or=8 and DWI-ASPECTS 8>or=. We divided patients into matched and mismatched patient groups, and compared them with respect to background characteristics, neurological findings, laboratory data, radiological findings and outcome.

RESULTS

There were 35 CDM-positive patients (P group, 40.2%) and 52 CDM-negative patients (N group , 59.8%). P group patients had a higher risk of early neurological deterioration (END) than N group patients (37.1% vs 13.5%, p<0.05), which were always accompanied by lesion growth defined by 2 or more points decrease on ASPECTS (36 to 72 hours after onset on CT). The NIHSS at entry were significantly lower in the P group, but there was no difference in the outcome at three months measured by the modified Rankin Scale. However, CDM was not an independent predictor of END by multiple logistic regression analysis.

CONCLUSIONS

Patients with CDM had high rate of early neurological deterioration and lesion growth. CDM defined as NIHSS>or=8 and DWI-ASPECTS>or=8 can be another marker for detecting patients with tissue at risk of infarction, but more work is needed to clarify whether this CDM method is useful in acute stroke management.

Characterization of a thromboembolic photochemical model of repeated stroke in mice

Many stroke research groups utilize the model of middle cerebral artery occlusion induced by insertion of an intraluminal thread, owing to its pragmatism and reliability of cerebral infarct generation. However, 75% of stroke cases result from a thromboembolic event and 10% from occlusive atherothrombosis in situ. Here, we characterize a mouse model of repeated thromboembolic stroke, which closely mimics the intravascular pathophysiology of arterial thrombus generation from an atherosclerotic plaque, and subsequent release of a thrombus into the cerebral circulation as an embolus. Common carotid artery thrombosis (CCAT) was induced photochemically leading to non-occlusive platelet aggregation in C57/BL6 male mice (n=35), and was followed by mechanical assistance to facilitate release of the thrombus (MRT) and thus promote embolism. Six experimental groups, differing by changes in the surgical protocol, were used for the purpose of determining which such procedure yielded the most reliable and consistent brain infarct volumes with the lowest mortality at 3 days after surgery. The group which best satisfied these conditions was a double insult group which consisted of animals that underwent CCAT for 2 min by means of argon laser irradiation (514.5 nm) at an intensity of ca. 130 W/cm(2), with concomitant injection of erythrosin B (EB) (35 mg/kg infused over those same 2 min), followed by MRT 1 min later; the entire procedure was repeated 24h later. This group showed a percent of brain lesion volume of 15+/-4% (mean+/-S.D.) with no associated 3-day mortality. Compared to a single insult group which sustained a percent brain lesion volume of 7+/-3%, there was a statistically significant (p<0.05) increase in the volume of infarction in the double-insult group.

Treating the acute stroke patient as an emergency: current practices and future opportunities

Developments in acute stroke therapy have followed advances in the understanding of the evolving pathophysiology in both ischaemic stroke and intracerebral haemorrhage (ICH). In ischaemic stroke, rapid reperfusion of the ischaemic penumbra with thrombolysis within 3 h of symptom onset is of proven benefit, but few patients currently receive therapy, mainly due to the short-time window and lack of stroke expertise. In ICH, a recent study indicated that a haemostatic agent can limit ongoing bleeding and improve outcomes when administered within 4 h of stroke onset. These advances in acute stroke therapy underlie the concept that 'time is brain' and that urgent intervention can limit cerebral damage. Neuroprotective therapy could offer the prospect of a greater proportion of stroke patients receiving treatment, potentially before imaging and even in the ambulance setting. Virtually all stroke patients would benefit from receiving multidisciplinary care in acute stroke units.

Perfusion computed tomography: prediction of final infarct extent and stroke outcome

The Alberta Stroke Program Early Computed Tomography Score (ASPECTS) has not been previously applied to perfusion CT (CTP). Five raters assigned ASPECTS to baseline noncontrast CT (NCCT), CT angiography source images (CTA-SI), CTP source images (CTP-SI), and CTP maps of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) from 37 consecutive patients with less than 6-hour anterior circulation ischemic stroke. Major reperfusion was identified on follow-up imaging. Mean baseline ASPECTS was compared with follow-up imaging ASPECTS. Rates of favorable outcome were compared for dichotomized baseline ASPECTS. In patients with major reperfusion, mean CBV and CTP-SI ASPECTS closely predicted final infarct ASPECTS. In patients without major reperfusion, mean CBF and MTT ASPECTS best predicted final infarct ASPECTS. There were significant increases in rates of favorable outcome for CTP-SI and CBV ASPECTS of greater than 6, versus less than or equal to 6, but not for other baseline CT modalities. ASPECTS applied to CTP is more accurate at identifying the extent of reversible and irreversible ischemia and at predicting final clinical outcome than NCCTor CTA-SI.

Rodent models of focal stroke: size, mechanism, and purpose

Rodent stroke models provide the experimental backbone for the in vivo determination of the mechanisms of cell death and neural repair, and for the initial testing of neuroprotective compounds. Less than 10 rodent models of focal stroke are routinely used in experimental study. These vary widely in their ability to model the human disease, and in their application to the study of cell death or neural repair. Many rodent focal stroke models produce large infarcts that more closely resemble malignant and fatal human infarction than the average sized human stroke. This review focuses on the mechanisms of ischemic damage in rat and mouse stroke models, the relative size of stroke generated in each model, and the purpose with which focal stroke models are applied to the study of ischemic cell death and to neural repair after stroke.