Endovascular treatment for acute ischemic stroke

Ischemic stroke penumbra and extracorporeal ozone treatment

The course of events in ischemic strokes is normally seen from a point in which the penumbra is already in place. Since there is no known treatment for edema reduction, mainstream medicine focuses on re-opening the occluded vessel. Here we show that reducing the penumbra saves neuronal units from undergoing apoptosis.

Quantification of errors in ordinal outcome scales using shannon entropy: effect on sample size calculations

Objective

Clinical trial outcomes often involve an ordinal scale of subjective functional assessments but the optimal way to quantify results is not clear. In stroke, the most commonly used scale, the modified Rankin Score (mRS), a range of scores (“Shift”) is proposed as superior to dichotomization because of greater information transfer. The influence of known uncertainties in mRS assessment has not been quantified. We hypothesized that errors caused by uncertainties could be quantified by applying information theory. Using Shannon’s model, we quantified errors of the “Shift” compared to dichotomized outcomes using published distributions of mRS uncertainties and applied this model to clinical trials.

Methods

We identified 35 randomized stroke trials that met inclusion criteria. Each trial’s mRS distribution was multiplied with the noise distribution from published mRS inter-rater variability to generate an error percentage for “shift” and dichotomized cut-points. For the SAINT I neuroprotectant trial, considered positive by “shift” mRS while the larger follow-up SAINT II trial was negative, we recalculated sample size required if classification uncertainty was taken into account.

Results

Considering the full mRS range, error rate was 26.1%±5.31 (Mean±SD). Error rates were lower for all dichotomizations tested using cut-points (e.g. mRS 1; 6.8%±2.89; overall p<0.001). Taking errors into account, SAINT I would have required 24% more subjects than were randomized.

Conclusion

We show when uncertainty in assessments is considered, the lowest error rates are with dichotomization. While using the full range of mRS is conceptually appealing, a gain of information is counter-balanced by a decrease in reliability. The resultant errors need to be considered since sample size may otherwise be underestimated. In principle, we have outlined an approach to error estimation for any condition in which there are uncertainties in outcome assessment. We provide the user with programs to calculate and incorporate errors into sample size estimation.

Efficacy of peripheral interventional radiologists performing endovascular stroke therapy guided by CT perfusion triage of patients

PURPOSE

To assess safety and efficacy of intraarterial mechanical thrombectomy for treatment of ischemic stroke in a community hospital by peripheral interventional radiologists employing computed tomography (CT) perfusion imaging for patient selection.

MATERIALS AND METHODS

Forty patients, 11 men (27.5%) and 29 women (72.5%), were treated between February 2008 and October 2011. Eligible patients had a National Institutes of Health Stroke Scale (NIHSS) score greater than 8 and diagnosis of large-vessel ischemic stroke by head CT angiogram, and met previously reported CT perfusion imaging triage criteria.

RESULTS

The baseline NIHSS score was 18.0 ± 7.9 (range, 8-35). Sixteen patients (40%) had a baseline NIHSS score greater than 20. Symptom onset was unknown in five patients. Symptom onset to device time in the remaining 35 patients was 254.8 minutes ± 150.9 (range, 75-775 min). A total of 65% of patients showed thrombolysis in cerebral infarction (TICI) 2a, 2b, or 3 flow following the procedure. Symptomatic intracranial hemorrhage was seen in four patients (10.0%). At 90 days, 32 patients (80%) were alive and eight (20%) had died. The modified Rankin scale (mRS) score at 90 days was no more than 2 in 20 patients (50.0%). The mean mRS score at 90 days was 2.9 ± 2.0 (range, 0-6). NIHSS score at 90 days was 5.1 ± 6.1 (range, 0-24). In patients with successful recanalization (ie, TICI 2 or 3 flow), a good clinical outcome (ie, mRS score ≤ 2) was achieved in 65.3% of patients (mean, 2.4 ± 1.9; range, 0-6), and 90-day mortality rate was 15.4%, compared with 28.6% in patients with TICI 0/1 flow.

CONCLUSIONS

Peripheral interventional radiologists who use CT perfusion imaging for patient triage can have good neurologic outcomes and provide sustainable, safe, and complete around-the-clock coverage for endovascular stroke treatment.

Status of endovascular interventions to treat acute ischemic stroke

OPINION STATEMENT

Acute stroke is a major component of neurology and one of few neurologic emergencies. Despite many efforts to increase treatment of acute ischemic stroke, we are still not able to treat a significant percentage of patients with intravenous tPA, typically because of time restrictions. Unfortunately, many patients do not present to medical attention within the short window for tPA administration. In addition, there are numerous contraindications for tPA, which make more patients ineligible. Endovascular treatment for acute ischemic stroke may help to expand the number of patients treated by extending the time window beyond the 3 to 4.5 hour constraints of IV tPA, and including patients with tPA contraindications such as use of oral anticoagulants. However, several recent studies have raised questions regarding the utility and efficacy of these procedures. These studies should not discourage endovascular treatment of acute stroke, but should lead us to ask more questions and be proactive in seeking answers, and should make us carefully select the patient population to receive the treatment. Future studies should take advantage of the lessons learned from these recent trials, including the importance of using vascular imaging for inclusion criteria, and of utilizing the latest and most advanced devices and techniques. Endovascular therapy will continue to evolve into what will hopefully be a clinically significant alternative therapy for acute ischemic stroke.

Acute stroke management in patients with known or suspected atrial fibrillation

Atrial fibrillation (AF) is an important cause of ischemic stroke, especially in older individuals. Strokes attributed to AF are often large and result in a high rate of fatality. The new oral anticoagulants offer advantages over warfarin in terms of dosing, pharmacokinetic characteristics, and lower rates of intracranial hemorrhage, but pose new management questions for physicians treating these patients. The management of acute stroke is not modified by the presence of AF, but is unique with respect to management of anticoagulation in the hyperacute and acute phases. We will review and discuss acute treatment options in anticoagulated patients with ischemic stroke, anticoagulation discontinuation, and timing of initiation with old and new oral anticoagulants, and managing intracranial hemorrhage in anticoagulated patients. We will end by briefly discussing investigations of stroke patients with suspected cardioembolic stroke.

Strategies to improve recovery in acute ischemic stroke patients: Iberoamerican Stroke Group Consensus

Stroke is not only a leading cause of death worldwide but also a main cause of disability. In developing countries, its burden is increasing as a consequence of a higher life expectancy. Whereas stroke mortality has decreased in developed countries, in Latin America, stroke mortality rates continue to rise as well as its socioeconomic dramatic consequences. Therefore, it is necessary to implement stroke care and surveillance programs to better describe the epidemiology of stroke in these countries in order to improve therapeutic strategies. Advances in the understanding of the pathogenic processes of brain ischemia have resulted in development of effective therapies during the acute phase. These include reperfusion therapies (both intravenous thrombolysis and interventional endovascular approaches) and treatment in stroke units that, through application of management protocols directed to maintain homeostasis and avoid complications, helps to exert effective brain protection that decreases further cerebral damage. Some drugs may enhance protection, and besides, there is increasing knowledge about brain plasticity and repair mechanisms that take place for longer periods beyond the acute phase. These mechanisms are responsible for recovery in certain patients and are the focus of basic and clinical research at present. This paper discusses recovery strategies that have demonstrated clinical effect, or that are promising and need further study. This rapidly evolving field needs to be carefully and critically evaluated so that investment in patient care is grounded on well-proven strategies.

Thrombolysis (different doses, routes of administration and agents) for acute ischaemic stroke

BACKGROUND

Stroke is a leading cause of death and disability world wide. Thrombolysis with recombinant tissue plasminogen activator (rt-PA) is licensed for treatment of acute ischaemic stroke in the early hours after symptom onset. It has been shown in randomised controlled trials (RCTs) and the 2009 Cochrane review of thrombolysis for acute ischaemic stroke to reduce dependency but at the increased risk of intracranial haemorrhage. Methods to reduce the risk of haemorrhage while retaining or enhancing the benefit could increase the use of thrombolytic treatment. While most available information comes from RCTs of intravenous rt-PA at 0.9 mg/kg, it is possible that other doses, drugs and other routes of administration might increase benefit and reduce the hazard.

OBJECTIVES

To assess the risks and benefits of different thrombolytic agents, doses and routes of administration for the treatment of acute ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (May 2012), MEDLINE (1966 to May 2012) and EMBASE (1980 to May 2012). We handsearched journals and conference proceedings, searched ongoing trials registers and contacted pharmaceutical companies and researchers.

SELECTION CRITERIA

Unconfounded randomised and quasi-randomised trials of different doses of a thrombolytic agent, or different agents, or the same agent given by different routes, in people with confirmed acute ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and quality, and extracted the data using a structured proforma. We cross-checked and resolved discrepancies by discussion to reach consensus. We obtained translations and additional information from study authors where required.

MAIN RESULTS

We included 20 trials involving 2527 patients. Concealment of allocation was poorly described. Different doses (of tissue plasminogen activator, urokinase, desmoteplase or tenecteplase) were compared in 13 trials (N = 1433 patients). Different agents (tissue plasminogen activator versus urokinase, tissue-cultured urokinase versus conventional urokinase, tenecteplase versus tissue plasminogen activator) were compared in five trials (N = 875 patients). Five trials (N = 485) compared different routes of administration. As some trials compared different agents and different doses, some patients contributed to two analyses. There was an approximately three-fold increase in fatal intracranial haemorrhages in patients allocated to higher than to lower doses of the same thrombolytic drug (odds ratio (OR) 2.71, 95% confidence interval (CI) 1.22 to 6.04). There was no difference in the number of patients who were dead or dependent at the end of follow-up between those allocated higher or lower doses of thrombolytic drug (OR 0.86, 95% CI 0.62 to 1.19). Higher versus lower doses of desmoteplase were associated with more deaths at the end of follow-up (OR 3.21, 95% CI 1.23 to 8.39). There was no evidence of any benefit for intra-arterial over intravenous treatment.

AUTHORS' CONCLUSIONS

These limited data suggest that higher doses of thrombolytic agents may lead to higher rates of bleeding. However, the evidence is inadequate to conclude whether lower doses of thrombolytic agents are more effective than higher doses, or whether one agent is better than another, or which route of administration is the best, for acute ischaemic stroke. At present, intravenous rt-PA at 0.9mg/kg as licensed in many countries appears to represent best practice and other drugs, doses or routes of administration should only be used in randomised controlled trials.

Endovascular treatment of acute ischemic stroke

Endovascular stroke therapy has revolutionized the management of patients with acute ischemic stroke in the last decade and has facilitated the development of sophisticated stroke imaging techniques and a multitude of thrombectomy devices. This article reviews the scientific basis and current evidence available to support endovascular revascularization and provides brief technical details of the various methods of endovascular thrombectomy with case examples.

Advances in the critical care management of ischemic stroke

Given recent advances in diagnostic modalities and revascularization capabilities, clinicians are not only able to rapidly and accurately identify acute ischemic stroke, but may also be able to aggressively intervene to minimize the extent of infarction. In those cases where revascularization cannot occur and/or the extent of infarction is large, there are multiple strategies to prevent secondary decompensation as the stroke evolves, for instance, if malignant cerebral edema should develop. In this paper, we will review the indications for specialized ICU care for an ischemic stroke patient, the treatment principles, and strategies employed by neurointensivists to minimize secondary neuronal injury, the literature in support of such strategies (and the questions to be addressed by future studies), all with the ultimate goal of increasing the likelihood of favorable neurologic outcomes in our ischemic stroke population.

Unanswered questions in thrombolytic therapy for acute ischemic stroke

This article reviews some of the current literature in support or against extension of the intravenous tissue plasminogen activator window, use of intra-arterial therapy or devices, as well alternative pharmacologic therapies that may extend the window for treatment of patients with acute ischemic stroke, with consideration of the relative risk of thrombolytic complications, factors for worse outcomes, and unclear stroke onset, as seen in patients with wake-up stroke. The issue of newer concomitant antithrombotic therapies as they affect the decision for acute ischemic stroke thrombolytic therapy is also explored.

Emerging issues in acute ischemic stroke

In this update we review studies on a wide range of topics, from diagnostic aspects of acute stroke to the clinical implications of the complex interaction between the brain and the immune system. Recent randomized trials and observational studies have reinforced the effectiveness of intravenous thrombolysis with t-PA in patients that qualify for this treatment, including patients presenting with mild symptoms or on subtherapeutic oral anticoagulation. Despite all the negative studies on the endovascular treatment of acute stroke, the utility of newer mechanical thrombectomy devices in patients with stroke and large vessel occlusion is being assessed in ongoing clinical trials. In addition to the various revascularization therapies that have a limited time window, treatments aimed at protecting the neurovascular unit may be used in more patients if their efficacy is confirmed in humans, and experimental studies suggest that the modulation of specific aspects of the immune system may increase the likelihood of successful recovery after cerebral ischemia.

Endovascular thrombectomy following acute ischemic stroke: a single-center case series and critical review of the literature

Acute ischemic stroke (AIS) due to thrombo-embolic occlusion in the cerebral vasculature is a major cause of morbidity and mortality in the United States and throughout the world. Although the prognosis is poor for many patients with AIS, a variety of strategies and devices are now available for achieving recanalization in patients with this disease. Here, we review the treatment options for cerebrovascular thromboembolic occlusion with a focus on the evolution of strategies and devices that are utilized for achieving endovascular clot extraction. In order to demonstrate the progression of this treatment strategy over the past decade, we will also present a single-center case series of AIS patients treated with endovascular thrombectomy.