Intra-arterial therapy for acute ischemic stroke

The added value of risk assessment and subsequent targeted treatment for epileptic seizures after stroke: An early-HTA analysis

INTRODUCTION

The development of post-stroke epilepsy (PSE) is related to a worse clinical outcome in stroke patients. Adding a biomarker to the clinical diagnostic process for the prediction of PSE may help to establish targeted and personalized treatment for high-risk patients, which could lead to improved patient outcomes. We assessed the added value of a risk assessment and subsequent targeted treatment by conducting an early Health Technology Assessment.

METHODS

Interviews were conducted with four relevant stakeholders in the field of PSE to obtain a realistic view of the current healthcare and their opinions on the potential value of a PSE risk assessment and subsequent targeted treatment. The consequences on quality of life and costs of current care of a hypothetical care pathway with perfect risk assessment were modeled based on information from a literature review and the input from the stakeholders. Subsequently, the maximum added value (the headroom) was calculated. Sensitivity analyses were performed to test the robustness of this result to variation in assumed input parameters, i.e. the accuracy of the risk assessment, the efficacy of anti-seizure medication (ASM), and the probability of patients expected to develop PSE.

RESULTS

All stakeholders considered the addition of a predictive biomarker for the risk assessment of PSE to be of value. The headroom amounted to €12,983. The sensitivity analyses demonstrated that the headroom remained beneficial when varying the accuracy of the risk assessment, the ASM efficacy, and the number of patients expected to develop PSE.

DISCUSSION

We showed that a risk assessment for PSE development is potentially valuable. This work demonstrates that it is worthwhile to undertake clinical studies to evaluate biomarkers for the prediction of patients at high risk for PSE and to assess the value of targeted prophylactic treatment.

Characterization and Imaging of Lipid-Shelled Microbubbles for Ultrasound-Triggered Release of Xenon

Xenon (Xe) is a bioactive gas capable of reducing and stabilizing neurologic injury in stroke. The goal of this work was to develop lipid-shelled microbubbles for xenon loading and ultrasound-triggered release. Microbubbles loaded with either xenon (Xe-MB) or xenon and octafluoropropane (Xe-OFP-MB) (9:1 v/v) were synthesized by high-shear mixing. The size distribution and the frequency-dependent attenuation coefficient of Xe-MB and Xe-OFP-MB were measured using a Coulter counter and a broadband acoustic attenuation spectroscopy system, respectively. The Xe dose was evaluated using gas chromatography/mass spectrometry. The total Xe doses in Xe-MB and Xe-OFP-MB were 113.1 ± 13.5 and 145.6 ± 25.5 μl per mg of lipid, respectively. Co-encapsulation of OFP increased the total xenon dose, attenuation coefficient, microbubble stability (in an undersaturated solution), and shelf life of the agent. Triggered release of gas payload was demonstrated with 6-MHz duplex Doppler and 220-kHz pulsed ultrasound. These results constitute the first step toward the use of lipid-shelled microbubbles for applications such as neuroprotection in stroke.

Endovascular Therapy for Acute Ischemic Stroke: A Comprehensive Review of Current Status

Stroke remains among the leading causes of disability and death worldwide. Fibrinolytic therapy is associated with poor patency and functional outcomes. Recently, multiple randomized trials have been published that have consolidated the role of endovascular therapy for ischemic stroke due to large vessel occlusion in the anterior cerebral circulation. This manuscript reviews the current understanding of the endovascular management of acute stroke including technical aspects and current evidence base.

Utility of a rescue endovascular therapy for the treatment of major strokes refractory to full-dose intravenous thrombolysis

OBJECTIVE

Large artery occlusion (LAO) in patients with major stroke predicts poor revascularization by intravenous thrombolysis (IVT) and more likely results in a poor outcome. We focused on the effects of intra-arterial thrombolysis (IAT) and endovascular mechanical recanalization (EMR) as rescue therapies in major strokes refractory to IVT.

METHODS

A retrospective analysis of 87 patients (National Institutes of Health Stroke Scale >20), who did not respond to full-dose IVT due to LAO, was performed based on their endovascular therapy status. IAT was performed as an intraclot infusion of alteplase, and EMR was provided by the Solitaire device™ (Covidien, Dubin, Ireland). The recanalization and 3-month outcome rates after IAT/EMR were correlated with a group of patients who were scheduled to receive endovascular treatment but who underwent only IVT.

RESULTS

We achieved successful recanalization by IAT and EMR in 68.7% and 76.1% of patients, respectively. Despite no significant differences in mortality between IAT and EMR, a trend towards better outcomes after IAT and a statistically significant increase for outcome-modified Rankin scale (mRS) 0-3 (45.7%) and mRS 0-2 (34.9%) after EMR was noted when compared with IVT. The degree of recanalization did not correlate with the functional results except for the good-moderate outcome after successful recanalization by EMR.

CONCLUSION

EMR by the Solitaire device is a safe and beneficial method for the rescue treatment of patients with major stroke whose neurological status does not improve and who fail to recanalize the LAO after a 1-h full dose of IVT.

ADVANCES IN KNOWLEDGE

The article verifies efficiency of the Solitaire device in major strokes.

Temporal evolution of intraparenchymal hyperdensity after intra-arterial therapy in patients with ischemic stroke: optimal discrimination between hemorrhage and iodinated contrast

PURPOSE

CT hyperattenuation arising from iodinated contrast has a different temporal evolution than that arising due to hemorrhage. This paper presents a method for optimal discrimination between hemorrhage and iodinated contrast in a postintervention CT in stroke patients.

METHODS

We analyzed the brain computed tomography (CT) scans of consecutive patients with intraparenchymal hyperattenuation due to hemorrhage (n=41), those due to iodinated contrast alone (n=24), and those due to contrast mixed with hemorrhage after reperfusion therapy (n=14) in stroke patients. The difference between the maximum enhancement in hyperattenuation in the affected area and the corresponding contralateral area, dubbed Relative Maximum Enhancement (RME), was tracked over time. We fitted regression models to the RME changes due to hemorrhage and contrast to describe their temporal decay, and then derived the optimal discriminant curve that distinguishes the two. A computer algorithm coregistered the baseline and follow-up CT scans and performed pixel-by-pixel comparison to determine hemorrhage and iodinated contrast based on the RME changes with respect to the discriminant curve.

RESULTS

For both hemorrhage (k= -0.004, R (2) =0.7) and iodinated contrast (k= -0.064, R (2)  =0.9), the temporal evolution of RMEs were best fitted by exponential decay curves, with respective half-lives of 192.3 and 10.7 h. An exponential decay model (k= -0.026) for optimal discrimination of hemorrhage vs. contrast was fitted. The computer algorithm implementing this model was successful in predicting the presence of hemorrhage in a hyperdense lesion with sensitivity =93% and specificity =91%.

CONCLUSION

Intraparenchymal hemorrhage and contrast have markedly different decay half-lives that can be used to assess hemorrhage in a hyperdense lesion on a CT scan after intra-arterial therapy.

Functional characterization of fibrinolytic metalloproteinases (colombienases) isolated from Bothrops colombiensis venom

Researchers trying to improve the safety and efficacy of fibrinolytic therapy have been isolating fibrinolytic enzymes from snake venoms. Two fibrinolytic enzymes, colombienases 1 and 2, with significant activity have been isolated from the venom of Bothrops colombiensis.

METHODS

The colombienases were characterized for various biological activities which include hemorrhagic, fibrinogenolytic, proteolytic, hemolytic, edematogenic and cytotoxic.

RESULTS

Colombienases directly acted on fibrin by degrading fibrinogen Aα and Bβ chains without activating the fibrinolytic system (plasminogen/plasmin), additionally colombienase-2 degraded fibrinogen γ chains as well as the fibronectin molecule. Laminin and type IV collagen were colombienases resistant. Gelatin-zymogram activity was present in B. colombiensis venom (BcV) bands between 64 and 148 kDa. All activities were abolished by metalloproteinases inhibitors. Both enzymes lacked hemorrhagic, hemolytic, cytotoxic, plasminogen activator and coagulant activities.

CONCLUSIONS

Both colombienases had direct fibrino(geno)lytic activity without other toxic side effects including in vivo hemorrhaging, which could be promising in terms of therapeutic potential as thrombolytic agents.

Poised for success: implementation of sound conditioning strategies to promote endogenous protective responses to stroke in patients

The following perspective represents our summary of questions, ideas, concerns, and recommendations expressed by speakers and discussants at the second Biennial Translational Preconditioning Workshop held in Miami in December 2011.

Intra-arterial vasodilator use during endovascular therapy for acute ischemic stroke might improve reperfusion rate

Treatment of acute ischemic stroke (AIS) is an evolving field. New treatment options are still needed in order to achieve greater success rates for arterial recanalization. Intra-arterial therapy (lAT) is an option for AIS patients who are not good candidates for intravenous (i.v.) recombinant tissue plasminogen activator (rt-PA) or where it has failed. While good data establishing the role of IAT in AIS management are lacking, the potential clinical efficacy of IAT is based on the premise that recanalization and reperfusion may result in better clinical outcome. Although lAT recanalization and reperfusion rates of large vessel occlusion are much higher than they are for i.v. rt-PA, IAT's radiological efficacy is still far from perfect. Vasodilator use during IAT for AIS may increase the recanalization and reperfusion rates of such therapy. In this report, we describe the radiographic and clinical outcomes in a cohort of AIS patients who received intra-arterial (i.a.) vasodilators during IAT and summarize the role of i.a. vasodilators in the process of recanalization and reperfusion.

Endovascular and neurosurgical management of acute ischemic stroke

Acute ischemic stroke is recognized as the third leading cause of death in the United States; improved treatments for management are important to reduce disability and death. The standard of care of acute stroke therapy has been reperfusion/recanalization of the occluded vessels using pharmacologic management, endovascular management, or a combination approach. Significant improvements have been made in the management with the use of endovascular therapy. This article reviews the literature on the endovascular and neurosurgical management of patients presenting with acute ischemic stroke and presents current evidence-based guidelines for endovascular or neurosurgical interventions outlined for management of ischemic stroke.

Beyond the time window of intravenous thrombolysis: standing by or by stenting?

Intravenous administration of tissue plasminogen activator within 4.5 h of symptom onset is presently the 'golden rule' for treating acute ischemic stroke. However, many patients miss the time window and others reject this treatment due to a long list of contraindications. Mechanical embolectomy has recently progressed as a potential alternative for treating patients beyond the time window for IV thrombolysis. In this paper, recent progress in mechanical embolectomy, angioplasty, and stenting in acute stroke is reviewed. Despite worries concerning the long-term clinical outcomes and increased risk of intracranial hemorrhage, favorable clinical outcomes may be achieved after mechanical embolectomy in carefully selected patients even 4.5 h after stroke onset. Potential steps should be prepared and attempted in these patients whose opportunity for recovery will elapse in a flash.