Intravenous thrombolysis plus hypothermia for acute treatment of ischemic stroke (ICTuS-L): final results

Therapeutic hypothermia in acute ischemic stroke

Induced hypothermia has been used for neuroprotection in cardiac and neurovascular procedures. Experimental and translational studies provide evidence for its utility in the treatment of ischemic cerebrovascular disease. Over the past decade, these principles have been applied to the clinical management of acute stroke. Varying induction methods, time windows, clinical indications, and adjuvant therapies have been studied. In this article the authors review the mechanisms and techniques for achieving therapeutic hypothermia in the setting of acute stroke, and they outline pertinent side effects and complications. The manuscript summarizes and examines the relevant clinical trials to date. Despite a reasonable amount of existing data, this review suggests that additional trials are warranted to define the optimal time window, temperature regimen, and precise clinical indications for induction of therapeutic hypothermia in the setting of acute stroke.

Mild hypothermia of 34°C reduces side effects of rt-PA treatment after thromboembolic stroke in rats

BACKGROUND

Hypothermia is neuroprotective in experimental stroke and may extend the so far limited therapeutic time window for thrombolysis. Therefore, hypothermia of 34°C and its effects on delayed thrombolysis including reperfusion-associated injury were investigated in a model of thromboembolic stroke (TE).

METHODS

Male Wistar rats (n = 48) were subjected to TE. The following treatment groups were investigated: control group - normothermia (37°C); thrombolysis group - rt-PA 90 min after TE; hypothermia by 34°C applied 1.5 to 5 hours after TE; combination therapy- hypothermia and rt-PA. After 24 hours infarct size, brain edema and neuroscore were assessed. Protein markers for inflammation and adhesion, gelatinase activity, and blood brain barrier (BBB) disruption were determined. MRI-measurements investigated infarct evolution and blood flow parameters.

RESULTS

The infarct volume and brain swelling were smaller in the hypothermia group compared to the other groups (p < 0.05 to p < 0.01). Thrombolysis resulted in larger infarct and brain swelling than all others. Hypothermia in combination with thrombolysis reduced these parameters compared to thrombolysis (p < 0.05). Moreover, the neuroscore improved in the hypothermia group compared to control and thrombolysis. Animals of the combination therapy performed better than after thrombolysis alone (p < 0.05). Lower serum concentration of sICAM-1, and TIMP-1 were shown for hypothermia and combination therapy. Gelatinase activity was decreased by hypothermia in both groups.

CONCLUSIONS

Therapeutic hypothermia reduced side-effects of rt-PA associated treatment and reperfusion in our model of TE.

Neuroprotection for ischaemic stroke: translation from the bench to the bedside

Neuroprotection seeks to restrict injury to the brain parenchyma following an ischaemic insult by preventing salvageable neurons from dying. The concept of neuroprotection has shown promise in experimental studies, but has failed to translate into clinical success. Many reasons exist for this including the heterogeneity of human stroke and the lack of methodological agreement between preclinical and clinical studies. Even with the proposed Stroke Therapy Academic Industry Roundtable criteria for preclinical development of neuroprotective agents for stroke, we have still seen limited success in the clinic, an example being NXY-059, which fulfilled nearly all the Stroke Therapy Academic Industry Roundtable criteria. There are currently a number of ongoing trials for neuroprotective strategies including hypothermia and albumin, but the outcome of these approaches remains to be seen. Combination therapies with thrombolysis also need to be fully investigated, as restoration of oxygen and glucose will always be the best therapy to protect against cell death from stroke. There are also a number of promising neuroprotectants in preclinical development including haematopoietic growth factors, and inhibitors of the nicotinamide adenine dinucleotide phosphate oxidases, a source of free radical production which is a key step in the pathophysiology of acute ischaemic stroke. For these neuroprotectants to succeed, essential quality standards need to be adhered to; however, these must remain realistic as the evidence that standardization of procedures improves translational success remains absent for stroke.

Hypothermia for acute brain injury--mechanisms and practical aspects

Hypothermia is widely accepted as the gold-standard method by which the body can protect the brain. Therapeutic cooling--or targeted temperature management (TTM)--is increasingly being used to prevent secondary brain injury in patients admitted to the emergency department and intensive care unit. Rapid cooling to 33 °C for 24 h is considered the standard of care for minimizing neurological injury after cardiac arrest, mild-to-moderate hypothermia (33-35 °C) can be used as an effective component of multimodal therapy for patients with elevated intracranial pressure, and advanced cooling technology can control fever in patients who have experienced trauma, haemorrhagic stroke, or other forms of severe brain injury. However, the practical application of therapeutic hypothermia is not trivial, and the treatment carries risks. Development of clinical management protocols that focus on detection and control of shivering and minimize the risk of other potential complications of TTM will be essential to maximize the benefits of this emerging therapeutic modality. This Review provides an overview of the potential neuroprotective mechanisms of hypothermia, practical considerations for the application of TTM, and disease-specific evidence for the use of this therapy in patients with acute brain injuries.

Application of mild therapeutic hypothermia on stroke: a systematic review and meta-analysis

Background. Stroke occurs due to an interruption in cerebral blood supply affecting neuronal function. Body temperature on hospital admission is an important predictor of clinical outcome. Therapeutic hypothermia is promising in clinical settings for stroke neuroprotection. Methods. MEDLINE/PubMed, CENTRAL, Stroke Center, and ClinicalTrials.gov were systematically searched for hypothermia intervention induced by external or endovascular cooling for acute stroke. NIH Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were the main stroke scales used, and mortality was also reported. A meta-analysis was carried out on stroke severity and mortality. Results. Seven parallel-controlled clinical trials were included in the meta-analysis. Sample sizes ranged from 18 to 62 patients, yielding a total of 288. Target temperature (∼33°C) was reached within 3-4 hours. Stroke severity (Cohen's d = −0.17, 95% CI: −0.42 to 0.08, P = 0.32; I² = 73%; Chi² = 21.89, P = 0.0001) and mortality (RR = 1.60, 95% CI: 0.93 to 2.78, P = 0.11; I² = 0%; Chi² = 2.88, P = 0.72) were not significantly affected by hypothermia. Discussion. Hypothermia does not significantly improve stroke severity; however, this finding should be taken with caution due to the high heterogeneity and limited number of included studies. No impact on mortality was observed.

Therapeutic hypothermia and prevention of acute kidney injury: a meta-analysis of randomized controlled trials

BACKGROUND

Therapeutic hypothermia has been shown to reduce neurological morbidity and mortality in the setting of out-of-hospital cardiac arrest and may be beneficial following brain injury and cardiopulmonary bypass. We conducted a systematic review to ascertain the effect of therapeutic hypothermia on development of acute kidney injury (AKI) and mortality.

METHODS

We searched for randomized controlled trials in MEDLINE through February 2011. We included trials comparing hypothermia to normothermia that reported kidney-related outcomes including, development of AKI, dialysis requirement, changes in serum creatinine, and mortality. We performed Peto fixed-effect and random-effects model meta-analyses, and meta-regressions.

RESULTS

Nineteen trials reporting on 2218 patients were included; in the normothermia group, the weighted rate of AKI was 4.2%, dialysis requirement 3.7%, and mortality 10.8%. By meta-analysis, hypothermia was not associated with a lower odds of AKI (odds ratio [OR] 1.01, 95% confidence interval [CI] 0.68, 1.51; P=0.95) or dialysis requirement (OR 0.81; 95% CI 0.30, 2.19; P=0.68); however, by meta-regression, a lower target cooling temperature was associated with a lower odds of AKI (P=0.01). Hypothermia was associated with lower mortality (OR 0.69; 95% CI 0.51, 0.92; P=0.01).

CONCLUSIONS

In trials that ascertained kidney endpoints, therapeutic hypothermia prevented neither the development of AKI nor dialysis requirement, but was associated with lower mortality. Different definitions and rates of AKI, differences in mortality rates, and concerns about the optimal target cooling temperature preclude definitive conclusions.

Hypothermia and Ischemic Stroke

OPINION STATEMENT: The use of tissue plasminogen activator (tPA) is the major treatment method for acute ischemic stroke, but it reaches only a very limited number of stroke patients. Although neuroprotectants may be useful in stroke patients in principle, promising animal data have not yet been successfully transferred to stroke patients. However, many arguments favor the successful translation of therapeutic hypothermia (TH) to stroke patients: it is a multimodal method, there is a strong correlation between fever and outcome in stroke patients, and TH has been shown to be beneficial in other kinds of acute brain injury (resuscitation, perinatal asphyxia). In addition, it is useful in controlling intracranial pressure caused by brain edema. So far, available data from clinical studies are not sufficient to recommend TH for the routine treatment of acute ischemic stroke. The quality of trials and the number of stroke patients treated by TH are far too low to prove efficacy or futility, but multicenter randomized controlled clinical trials are on their way. Studies in awake stroke patients will use TH very early in the clinical setting, which implies certain problems. The use of TH in awake individuals requires methods to suppress cold-induced vegetative responses such as shivering and sympathic activation, clinically relevant side effects that need to be monitored and treated carefully. In mass-occupying ischemic stroke, randomized trials will evaluate the neuroprotective effects of controlling edema and intracranial pressure. Because the optimal depth, duration, and methods of cooling are not clear, only large randomized controlled trials will set the baseline from which TH as a neuroprotective therapy can be optimized and brought successfully to stroke patients.

Therapeutic hypothermia for acute neurological injuries

Therapeutic hypothermia (TH) is the intentional reduction of core body temperature to 32°C to 35°C, and is increasingly applied by intensivists for a variety of acute neurological injuries to achieve neuroprotection and reduction of elevated intracranial pressure. TH improves outcomes in comatose patients after a cardiac arrest with a shockable rhythm, but other off-label applications exist and are likely to increase in the future. This comprehensive review summarizes the physiology and cellular mechanism of action of TH, as well as different means of TH induction and maintenance with potential side effects. Indications of TH are critically reviewed by disease entity, as reported in the most recent literature, and evidence-based recommendations are provided.

Therapeutic hypothermia in stroke and traumatic brain injury

Therapeutic hypothermia (TH) is considered to improve survival with favorable neurological outcome in the case of global cerebral ischemia after cardiac arrest and perinatal asphyxia. The efficacy of hypothermia in acute ischemic stroke (AIS) and traumatic brain injury (TBI), however, is not well studied. Induction of TH typically requires a multimodal approach, including the use of both pharmacological agents and physical techniques. To date, clinical outcomes for patients with either AIS or TBI who received TH have yielded conflicting results; thus, no adequate therapeutic consensus has been reached. Nevertheless, it seems that by determining optimal TH parameters and also appropriate applications, cooling therapy still has the potential to become a valuable neuroprotective intervention. Among the various methods for hypothermia induction, intravascular cooling (IVC) may have the most promise in the awake patient in terms of clinical outcomes. Currently, the IVC method has the capability of more rapid target temperature attainment and more precise control of temperature. However, this technique requires expertise in endovascular surgery that can preclude its application in the field and/or in most emergency settings. It is very likely that combining neuroprotective strategies will yield better outcomes than utilizing a single approach.

The Use of Hypothermia Therapy in Traumatic Ischemic / Reperfusional Brain Injury: Review of the Literatures

Therapeutic mild hypothermia has been used widely in brain injury. It has evaluated in numerous clinical trials, and there is strong evidence for the use of hypothermia in treating patients with several types of ischemic / reperfusional (I/R) injuries, examples being cardiac arrest and neonatal hypoxic-ischemic encephalopathy.In spite of many basic research projects demonstrating effectiveness, therapeutic hypothermia has not been proven effective for the heterogeneous group of traumatic brain injury patients in multicenter clinical trials. In the latest clinical trial, however, researchers were able to demonstrate the significant beneficial effects of hypothermia in one specific group; patients with mass evacuated lesions. This suggested that mild therapeutic hypothermia might be effective for I/R related traumatic brain injury.In this article we have reviewed much of the previous literature concerning the mechanisms of I/R injury to the protective effects of mild therapeutic hypothermia.

Impact of tissue plasminogen activator on the neurovascular unit: from clinical data to experimental evidence

About 15 million strokes occur each year worldwide. As the number one cause of morbidity and acquired disability, stroke is a major drain on public health-care funding, due to long hospital stays followed by ongoing support in the community or nursing-home care. Although during the last 10 years we have witnessed a remarkable progress in the understanding of the pathophysiology of ischemic stroke, reperfusion induced by recombinant tissue-type plasminogen activator (tPA-Actilyse) remains the only approved acute treatment by the health authorities. The objective of the present review is to provide an overview of our present knowledge about the impact of tPA on the neurovascular unit during acute ischemic stroke.

Neuroinflammation and cerebrovascular disease in old age: a translational medicine perspective

The incidence of cerebrovascular disease is highest in the elderly population. However, the pathophysiological mechanisms of brain response to cerebral ischemia in old age are currently poorly understood. Ischemic changes in the commonly used young animal stroke models do not reflect the molecular changes associated with the aged brain. Neuroinflammation and oxidative stress are important pathogenic processes occurring during the acute phase of cerebral ischemia. Free radical generation is also implicated in the aging process, and the combination of these effects in elderly stroke patients could explain the higher risk of morbidity and mortality. A better understanding of stroke pathophysiology in the elderly patient would assist in the development of new therapeutic strategies for this vulnerable age group. With the increasing use of reperfusion therapies, inflammatory pathways and oxidative stress remain attractive therapeutic targets for the development of adjuvant neuroprotective agents. This paper will discuss these molecular aspects of acute stroke and senescence from a bench-to-bedside research perspective.

Stroke research at a crossroad: asking the brain for directions

Ischemic stroke remains a vexing public health problem. Although progress has been made in prevention and supportive care, efforts to protect the brain from ischemic cell death have failed. Thus, no new treatment has made it from bench to bedside since tissue plasminogen activator was introduced in 1996. The brain has a remarkable capacity for self-preservation, illustrated by the protective responses induced by ischemia, preconditioning and exercise. Here we describe the mechanisms underlying brain self-protection, with the goal of identifying features that could provide insight into stroke therapy. Unlike traditional therapeutic approaches based on counteracting selected pathways of the ischemic cascade, endogenous neuroprotection relies on coordinated neurovascular programs that support cerebral perfusion, mitigate the harmful effects of cerebral ischemia and promote tissue restoration. Learning how the brain triggers and implements these protective measures may advance our quest to treat stroke.

Therapeutic hypothermia: benefits, mechanisms and potential clinical applications in neurological, cardiac and kidney injury

Therapeutic hypothermia involves the controlled reduction of core temperature to attenuate the secondary organ damage which occurs following a primary injury. Clinicians have been increasingly using therapeutic hypothermia to prevent or ameliorate various types of neurological injury and more recently for some forms of cardiac injury. In addition, some recent evidence suggests that therapeutic hypothermia may also provide benefit following acute kidney injury. In this review we will examine the potential mechanisms of action and current clinical evidence surrounding the use of therapeutic hypothermia. We will discuss the ideal methodological attributes of future studies using hypothermia to optimise outcomes following organ injury, in particular neurological injury. We will assess the importance of target hypothermic temperature, time to achieve target temperature, duration of cooling, and re-warming rate on outcomes following neurological injury to gain insights into important factors which may also influence the success of hypothermia in other organ injuries, such as the heart and the kidney. Finally, we will examine the potential of therapeutic hypothermia as a future kidney protective therapy.

Hypothermia is correlated with seizure absence in perinatal stroke

Within a single-center prospective cohort study of neonatal encephalopathy involving 315 subjects, 15 neonates were found to have a focal stroke on magnetic resonance imaging. These 15 patients were matched on the basis of gender and degree of encephalopathy to 30 neonates without stroke from the same cohort. On Bayley Scales of Infant Development, the stroke group had Mental Development Index scores that were 1.7 standard deviations lower compared with controls (P = .007). This association was no longer seen after adjustment for the presence of neonatal seizures (P = .11). Of the 15 patients with stroke, 5 had been treated with hypothermia. None of these 5 had seizures in the neonatal period, compared with 7 of the untreated 10. This is the first human study to demonstrate a potential treatment effect of therapeutic hypothermia on perinatal stroke. It was also shown that seizures are associated with worse cognitive outcomes for stroke that presents with encephalopathy.

Low Body Temperature Does Not Compromise the Treatment Effect of Alteplase

Background and Purpose—

Hypothermia is neuroprotective in ischemic stroke models. The influence of baseline body temperature on outcomes after thrombolytic therapy is unclear. We examined outcomes after alteplase treatment across baseline body temperature for patients with ischemic stroke in data held within the Virtual International Stroke Trials Archive (VISTA; 1998 to 2007).

Methods—

We collated data on age, baseline severity (National Institutes of Health Stroke Scale), and 90-day modified Rankin Scale score on patients presenting with acute ischemic stroke. We compared 90-day modified Rankin Scale score between thrombolyzed and nonthrombolyzed comparators across baseline body temperature. We report age and baseline National Institutes of Health Stroke Scale-adjusted Cochran-Mantel-Haenszel probability value and proportional OR with 95% CI for improved modified Rankin Scale distribution. We report temperature profiles over 72 hours after stroke by treatment group.

Results—

Rankin data were available for 5586 patients with acute ischemic stroke in VISTA (1980 received alteplase). Age and baseline severity were similar (age 68.0±13.0 years versus 69.9±12.3 years, National Institutes of Health Stroke Scale 14.2±5.2 versus 13.0±5.6). Alteplase was associated with improved outcome (OR, 1.49; 95% CI, 1.35 to 1.65, P <0.0001). Alteplase treatment effect was not associated with baseline temperature ( P =0.14). Point estimates showed benefit of alteplase treatment across 35.5°C to 37.5°C but showed a negative trend >37.5°C. Alteplase did not influence temperature profiles over 72 hours after stroke.

Conclusions—

There is no evidence of influence of body temperature on alteplase treatment response. These results are reassuring that low temperatures across a physiological range do not compromise therapeutic effect of alteplase.

Limited Therapeutic Time Windows of Mild-to-Moderate Hypothermia in a Focal Ischemia Model in Rat

Although many studies have shown the great potential of induced hypothermia in stroke treatment, we recognize that there are limitations to the protective effects of hypothermia even in the laboratory. Here, we review our experiments on the protective effects of mild-to-moderate hypothermia in rats. Focal ischemia was induced by bilateral common carotid artery (CCA) occlusion for 1 to 2 hours combined with permanent or transient middle cerebral artery (MCA) occlusion. We compared the effects of mild (33°C) and moderate (30°C) hypothermia, evaluated therapeutic time windows, and studied the underlying mechanisms. On review, our findings revealed that the protective effects of induced mild hypothermia (33°C) were limited, and the therapeutic time window of even moderate hypothermia (30°C) was very short in our specific models, although this limitation might be due to the relatively brief periods of hypothermia used. In addition, we found that hypothermia reduced brain injury by preserving Akt activity, PTEN phosphorylation and εPKC activity, while inhibiting ROS production, and δPKC activity.

Therapeutic hypothermia after cardiac arrest: experience at an academically affiliated community-based veterans affairs medical center

At laboratory and clinical levels, therapeutic hypothermia has been shown to improve neurologic outcomes and mortality following cardiac arrest. We reviewed each cardiac arrest in our community-based Veterans Affairs Medical Center over a three-year period. The majority of cases were in-hospital arrests associated with initial pulseless electrical activity or asystole. Of a total of 100 patients suffering 118 cardiac arrests, 29 arrests involved comatose survivors, with eight patients completing therapeutic cooling. Cerebral performance category scores at discharge and six months were significantly better in the cooled cohort versus the noncooled cohort, and, in every case except for one, cooling was offered for appropriate reasons. Mean time to initiation of cooling protocol was 3.7 hours and mean time to goal temperature of 33°C was 8.8 hours, and few complications clearly related to cooling were noted in our case series. While in-patient hospital mortality of cardiac arrest was high at 65% mortality during hospital admission, therapeutic hypothermia was safe and feasible at our center. Our cooling times and incidence of favorable outcomes are comparable to previously published reports. This study demonstrates the feasibility of implementing, a cooling protocol a community setting, and the role of neurologists in ensuring effective hospital-wide implementation.

Experimental and clinical use of therapeutic hypothermia for ischemic stroke: opportunities and limitations

Stroke remains a disease with a serious impact on quality of life but few effective treatments exist. There is an urgent need to develop and/or improve neuroprotective strategies to combat this. Many drugs proven to be neuroprotective in experimental models fail to improve patient outcome in a clinical setting. An emerging treatment, therapeutic hypothermia (TH), is a promising neuroprotective therapy in stroke management. Several studies with TH in experimental models and small clinical trials have shown beneficial effects. Despite this, implementation into the clinical setting is still lacking due to methodological considerations as well as hypothermia-related complications. This paper discusses the possible opportunities and limitations of the use of TH in animal models and the translation into the clinic.

Investigational therapies for ischemic stroke: neuroprotection and neurorecovery

Stroke is one of the leading causes of death and disability worldwide. Current treatment strategies for ischemic stroke primarily focus on reducing the size of ischemic damage and rescuing dying cells early after occurrence. To date, intravenous recombinant tissue plasminogen activator is the only United States Food and Drug Administration approved therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window. The pathophysiology of stroke is complex and it involves excitotoxicity mechanisms, inflammatory pathways, oxidative damage, ionic imbalances, apoptosis, angiogenesis, neuroprotection, and neurorestoration. Regeneration of the brain after damage is still active days and even weeks after a stroke occurs, which might provide a second window for treatment. A huge number of neuroprotective agents have been designed to interrupt the ischemic cascade, but therapeutic trials of these agents have yet to show consistent benefit, despite successful preceding animal studies. Several agents of great promise are currently in the middle to late stages of the clinical trial setting and may emerge in routine practice in the near future. In this review, we highlight select pharmacologic and cell-based therapies that are currently in the clinical trial stage for stroke.

Post-stroke hypothermia provides neuroprotection through inhibition of AMP-activated protein kinase

Hypothermia is robustly protective in pre-clinical models of both global and focal ischemia, as well as in patients after cardiac arrest. Although the mechanism for hypothermic neuroprotection remains unknown, reducing metabolic drive may play a role. Capitalizing on the beneficial effects of hypothermia while avoiding detrimental effects such as infection will be the key to moving this therapy forward as a treatment for stroke. AMPK is a master energy sensor that monitors levels of key energy metabolites. AMPK is activated via phosphorylation (pAMPK) when cellular energy levels are low, such as that seen during ischemia. AMPK activation appears to be detrimental in experimental stroke, likely via exacerbating ischemia-induced metabolic failure. We tested the hypothesis that hypothermia reduces AMPK activation. First, it was found that hypothermia reduced infarct after middle cerebral artery occlusion. Second, induced hypothermia reduced brain pAMPK in both sham control and stroke mice. Third, hypothermic neuroprotection was ameliorated after administration of compound C, an AMPK inhibitor. Finally, deletion of one of the catalytic isoforms of AMPK completely reversed the effect of hypothermia on stroke outcome after both acute and chronic survival. These effects were mediated by a reduction in AMPK activation rather than a reduction in LKB1, an upstream AMPK kinase. In summary, these studies provide evidence that hypothermia exerts its protective effect in part by inhibiting AMPK activation in experimental focal stroke. This suggests that AMPK represents a potentially important biological target for stroke treatment.

Critical care of patients with acute ischemic and hemorrhagic stroke: update on recent evidence and international guidelines

Patients with acute ischemic and hemorrhagic stroke are often managed in a critical care setting. Disturbances in BP, body temperature, and serum glucose are commonly observed but their management remains controversial. The reversal of antithrombotic medications and prognostication are especially challenging for intracerebral hemorrhages. This review highlights recent clinical trials and the recommendations found in international guidelines relevant to these topics. We aim to provide a practical and brief, yet current, review of these more problematic areas of stroke care.

Sonothrombolysis: an emerging modality for the treatment of acute ischemic and hemorrhagic stroke

To date, it is believed that rapid removal of impedances hindering normal blood circulation in the brain would salvage ischemic tissue. Hence, most treatment modalities undergoing clinical evaluation for treatment of stroke are focused on faster recanalization in acute ischemic stroke or faster hematoma mass reduction in hemorrhagic stroke. Therapeutic ultrasound is among the promising emerging modalities being clinically evaluated to meet this purpose. This review provides an overview of existing clinical data in evaluating sonothrombolysis applications in treatment of acute ischemic and hemorrhagic stroke. Furthermore, the present status of clinical evaluation of microbubbles as a potential adjuvant to this modality is reviewed.

Hypothermia, immune suppression and SDD: can we have our cake and eat it?

In vitro studies and clinical observations suggest that both accidental and controlled/therapeutic hypothermia have a strong immunosuppressive effect, and that hypothermia increases the risk of infections, especially wound infections and pneumonia. In the previous issue of Critical Care, Kamps and colleagues report that when hypothermia was used for prolonged periods in patients with severe traumatic brain injury in conjunction with selective decontamination of the digestive tract, the risks of infection were the same or lower in patients treated with therapeutic cooling. The risk of infection is widely regarded as the most important danger of therapeutic cooling. The findings of Kamps and colleagues need to be verified in prospective trials and in higher-resistance environments, but raise the possibility of cooling for prolonged periods with greatly reduced risk. We may be able to have our cake and eat it.

Vascular Dysfunction in Brain Hemorrhage: Translational Pathways to Developing New Treatments from Old Targets

Hemorrhagic stroke which is a form of stroke that affects 20% of all stroke patients is a devastating condition for which new treatments must be developed. Current treatment methods are quite insufficient to reduce long term morbidity and high mortality rate, up to 50%, associated with bleeding into critical brain structures, into ventricular spaces and within the subarachnoid space. During the last 10-15 years, significant advances in the understanding of important mechanisms that contribute to cell death and clinical deficits have been made. The most important observations revolve around a key set of basic mechanisms that are altered in brain bleeding models, including activation of membrane metalloproteinases, oxidative stress and both inflammatory and coagulation pathways. Moreover, it is now becoming apparent that brain hemorrhage can activate the ischemic stroke cascade in neurons, glial cells and the vascular compartment. The activation of multiple pathways allows comes the opportunity to intervene pharmacologically using monotherapy or combination therapy. Ultimately, combination therapy or pleiotropic compounds with multi-target activities should prove to be more efficacious than any single therapy alone. This article provides a comprehensive look at possible targets for small molecule intervention as well as some new approaches that result in metabolic down-regulation or inhibition of multiple pathways simultaneously.

Therapeutic hypothermia for brain ischemia: where have we come and where do we go?

Mild hypothermia is an established neuroprotectant in the laboratory, showing remarkable and consistent effects across multiple laboratories and models of brain injury. At the clinical level, mild hypothermia has shown benefits in patients who have experienced cardiac arrest and in some pediatric populations experiencing hypoxic brain insults. Its role, however, in stroke therapy has yet to be established. Translating preclinical data to the clinical arena presents unique challenges with regard to cooling in patients who are generally awake and may require additional therapies, such as reperfusion. We review the state of therapeutic hypothermia in ischemic and hemorrhagic stroke and provide an outlook for its role in stroke therapy.

Hypothermia after acute ischemic stroke

Induced hypothermia after ischemic stroke is a promising neuroprotective therapy and is the most potent in pre-clinical models. Technological limitations and homeostatic mechanisms that maintain core body temperature, however, have limited the clinical application of hypothermia. Advances in intravascular cooling and successful trials of hypothermia after global cerebral ischemia, such as in cardiac arrest and neonatal asphyxia, have renewed interest in hypothermia for stroke.

Cooling therapy for acute stroke

BACKGROUND

Increased body temperatures are common in patients with acute stroke and are associated with poor outcome. In animal models of focal cerebral ischaemia, temperature-lowering therapy reduces infarct volume. In patients with acute stroke, lowering temperature may therefore improve outcome. This is an update of a Cochrane review first published in 1999.

OBJECTIVES

To assess the effects of pharmacological and physical strategies to reduce body or brain temperature in patients with acute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (last searched December 2007). In addition, we searched MEDLINE and EMBASE (January 1998 to December 2007). We scanned references and contacted authors of included trials. For the previous version of this review, the authors contacted pharmaceutical companies and manufactures of cooling equipment in this field.

SELECTION CRITERIA

We considered all completed randomised or non-randomised controlled clinical trials, published or unpublished, where pharmacological or physical strategies or both to reduce temperature were applied in patients with acute ischaemic stroke or intracerebral haemorrhage. Outcome measures were death or dependency (modified Rankin Scale score >/= 3) at the end of follow up, and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria, assessed trial quality, and extracted and cross-checked the data.

MAIN RESULTS

We included five pharmacological temperature reduction trials and three physical cooling trials involving a total of 423 participants. We found no statistically significant effect of pharmacological or physical temperature-lowering therapy in reducing the risk of death or dependency (odds ratio (OR) 0.9, 95% confidence interval (CI) 0.6 to 1.4) or death (OR 0.9, 95% CI 0.5 to 1.5). Both interventions were associated with a non-significant increase in the occurrence of infections.

AUTHORS' CONCLUSIONS

There is currently no evidence from randomised trials to support routine use of physical or pharmacological strategies to reduce temperature in patients with acute stroke. Large randomised clinical trials are needed to study the effect of such strategies.

Multimodal neuroprotective therapy with induced hypothermia after ischemic stroke

Neuroprotective therapies have so far failed to provide improved neurological function and outcome after stroke. A recent focus on multimodal therapies, including the combination of neuroprotective medications with hypothermia, opens a promising new treatment strategy. Advances in hypothermia administration make it one of the most promising neuroprotective therapies available and an ideal candidate for combination with other neuroprotective approaches.