Effect of endovascular hypothermia on acute ischemic edema: morphometric analysis of the ICTuS trial

Targeted Temperature Management for Patients with Acute Ischemic Stroke: A Literature Review

Despite significant advances in medical imaging, thrombolytic therapy, and mechanical thrombectomy, acute ischemic strokes (AIS) remain a major cause of mortality and morbidity globally. Targeted temperature management (TTM) has emerged as a potential therapeutic intervention, aiming to mitigate neuronal damage and improve outcomes. This literature review examines the efficacy and challenges of TTM in the context of an AIS. A comprehensive literature search was conducted using databases such as PubMed, Cochrane, Web of Science, and Google Scholar. Studies were selected based on relevance and quality. We identified key factors influencing the effectiveness of TTM such as its timing, depth and duration, and method of application. The review also highlighted challenges associated with TTM, including increased pneumonia rates. The target temperature range was typically between 32 and 36 °C, with the duration of cooling from 24 to 72 h. Early initiation of TTM was associated with better outcomes, with optimal results observed when TTM was started within the first 6 h post-stroke. Emerging evidence indicates that TTM shows considerable potential as an adjunctive treatment for AIS when implemented promptly and with precision, thereby potentially mitigating neuronal damage and enhancing overall patient outcomes. However, its application is complex and requires the careful consideration of various factors.

Novel Focal Therapeutic Hypothermia Device for Treatment of Acute Neurologic Injury: Large Animal Safety and Efficacy Trial

Objective  Therapeutic hypothermia is a potentially powerful and controversial clinical tool for neuroprotection following acute neurologic pathology, particularly vascular injury. Indeed, therapeutic hypothermia remains a standard of care for postcardiac arrest ischemia and acute neonatal hypoxic-ischemic encephalopathy, improving both survival and outcomes. Although therapeutic hypothermia remains promising for cellular and systems-based neuronal protection in other neurologic injury states, the systemic side effects have limited clinical utility, confounded analysis of potential neurologic benefits, and precluded the completion of meaningful clinical trials. Methods  To address such limitations, we developed and tested a novel, minimally invasive, neurocritical care device that employs continuous circulation of cold saline through the pharyngeal region to deliver focal cerebrovascular cooling. We conducted a preclinical safety and efficacy trial in six adult porcine animals to assess the validity and functionality of the NeuroSave device, and assess cooling potential following middle cerebral artery occlusion ( n  = 2). Results  NeuroSave consistently lowered brain parenchymal temperature by a median of 9°C relative to core temperature within 60 minutes of initiation, including in ischemic cerebral parenchyma. The core body temperature experienced a maximal reduction of 2°C, or 5% of body temperature, with no associated adverse effects identified. Conclusion  The present study uses a large animal preclinical model to demonstrate the safety and efficacy of a novel, noninvasive device for the induction of robust and systemically safe hypothermia within the brain.

Extracorporeal Life Support for Cardiac Arrest and Cardiogenic Shock

The rising incidence and recognition of cardiogenic shock has led to an increase in the use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). As clinical experience with this therapy has increased, there has also been a rapid growth in the body of observational and randomized data describing the clinical and logistical considerations required to institute a VA-ECMO program with successful clinical outcomes. The aim of this review is to summarize this contemporary data in the context of four key themes that pertain to VA-ECMO programs: the principles of patient selection; basic hemodynamic and technical principles underlying VA-ECMO; contraindications to VA-ECMO therapy; and common complications and intensive care considerations that are encountered in the setting of VA-ECMO therapy.

Hemispheric CSF volume ratio quantifies progression and severity of cerebral edema after acute hemispheric stroke

As swelling occurs, CSF is preferentially displaced from the ischemic hemisphere. The ratio of CSF volume in the stroke-affected hemisphere to that in the contralateral hemisphere may quantify the progression of cerebral edema. We automatically segmented CSF from 1,875 routine CTs performed within 96 hours of stroke onset in 924 participants of a stroke cohort study. In 737 subjects with follow-up imaging beyond 24-hours, edema severity was classified as affecting less than one-third of the hemisphere (CED-1), large hemispheric infarction (LHI, over one-third the hemisphere), without midline shift (CED-2) or with midline shift (CED-3). Malignant edema was LHI resulting in deterioration, requiring osmotic therapy, surgery, or resulting in death. Hemispheric CSF ratio was lower on baseline CT in those with LHI (0.91 vs. 0.97, p < 0.0001) and decreased more rapidly in those with LHI who developed midline shift (0.01 per hour for CED-3 vs. 0.004/hour CED-2). The ratio at 24-hours was lower in those with midline shift (0.41, IQR 0.30-0.57 vs. 0.66, 0.56-0.81 for CED-2). A ratio below 0.50 provided 90% sensitivity, 82% specificity for predicting malignant edema among those with LHI (AUC 0.91, 0.85-0.96). This suggests that the hemispheric CSF ratio may provide an accessible early biomarker of edema severity.

High Chloride Burden and Clinical Outcomes in Critically Ill Patients With Large Hemispheric Infarction

Background: In general, disease severity has been found to be associated with abnormal chloride levels in critically ill patients, but hyperchloremia is associated with mixed results regarding patient-centered clinical outcomes. We aimed to investigate the impact of maximum serum chloride concentration on the clinical outcomes of critically ill patients with large hemispheric infarction (LHI).

Methods: We conducted a retrospective observational cohort study using prospective institutional neurocritical care registry data from 2013 to 2018. Patients with LHIs involving over two-thirds of middle cerebral artery territory, with or without infarction of other vascular territories, and a baseline National Institutes of Health Stroke Scale score of ≥13 were assessed. Those with a baseline creatinine clearance of <15 mL/min and required neurocritical care for <72 h were excluded. Primary outcome was in-hospital mortality. Secondary outcomes included 3-month mortality and acute kidney injury (AKI) occurrence. Outcomes were compared to different maximum serum chloride levels (5 mmol/L increases) during the entire hospitalization period using multivariable logistic regression analyses.

Results: Of 90 patients, 20 (22.2%) died in-hospital. Patients who died in-hospital had significantly higher maximum serum chloride levels than did those who survived up to hospital discharge (139.7 ± 8.1 vs. 119.1 ± 10.4 mmol/L; p < 0.001). After adjusting for age, sex, and Glasgow coma scale score, each 5-mmol/L increase in maximum serum chloride concentration was independently associated with an increased risk of in-hospital mortality (adjusted odds ratio (aOR), 4.34; 95% confidence interval [CI], 1.98–9.50; p < 0.001). Maximum serum chloride level was also an independent risk factor for 3-month mortality (aOR, 1.99 [per 5 mmol/L increase]; 95% CI, 1.42–2.79; p < 0.001) and AKI occurrence (aOR, 1.57 [per 5 mmol/L increase]; 95% CI, 1.18–2.08; p = 0.002).

Conclusions: High maximum serum chloride concentrations were associated with poor clinical outcomes in critically ill patients with LHI. This study highlights the importance of monitoring serum chloride levels and avoiding hyperchloremia in this patient population.

Association of Initial Illness Severity and Outcomes After Cardiac Arrest With Targeted Temperature Management at 36 °C or 33 °C

IMPORTANCE

It is uncertain what the optimal target temperature is for targeted temperature management (TTM) in patients who are comatose following cardiac arrest.

OBJECTIVE

To examine whether illness severity is associated with changes in the association between target temperature and patient outcome.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study compared outcomes for 1319 patients who were comatose after cardiac arrest at a single center in Pittsburgh, Pennsylvania, from January 2010 to December 2018. Initial illness severity was based on coma and organ failure scores, presence of severe cerebral edema, and presence of highly malignant electroencephalogram (EEG) after resuscitation.

EXPOSURE

TTM at 36 °C or 33 °C.

MAIN OUTCOMES AND MEASURES

Primary outcome was survival to hospital discharge, and secondary outcomes were modified Rankin Scale and cerebral performance category.

RESULTS

Among 1319 patients, 728 (55.2%) had TTM at 33 °C (451 [62.0%] men; median [interquartile range] age, 61 [50-72] years) and 591 (44.8%) had TTM at 36 °C (353 [59.7%] men; median [interquartile range] age, 59 [48-69] years). Overall, 184 of 187 patients (98.4%) with severe cerebral edema died and 234 of 243 patients (96.3%) with highly malignant EEG died regardless of TTM strategy. Comparing TTM at 33 °C with TTM at 36 °C in 911 patients (69.1%) with neither severe cerebral edema nor highly malignant EEG, survival was lower in patients with mild to moderate coma and no shock (risk difference, -13.8%; 95% CI, -24.4% to -3.2%) but higher in patients with mild to moderate coma and cardiopulmonary failure (risk difference, 21.8%; 95% CI, 5.4% to 38.2%) or with severe coma (risk difference, 9.7%; 95% CI, 4.0% to 15.3%). Interactions were similar for functional outcomes. Most deaths (633 of 968 [65.4%]) resulted after withdrawal of life-sustaining therapies.

CONCLUSIONS AND RELEVANCE

In this study, TTM at 33 °C was associated with better survival than TTM at 36 °C among patients with the most severe post-cardiac arrest illness but without severe cerebral edema or malignant EEG. However, TTM at 36 °C was associated with better survival among patients with mild- to moderate-severity illness.

Radiologic Measurement of Brain Swelling in Patients with Large Hemispheric Infarctions During Targeted Temperature Management

Brain herniation is most often the result of severe brain swelling and can rapidly lead to death or brain death. We retrospectively identified radiologic indicators to evaluate the effects of targeted temperature management (TTM) on the extent of cerebral edema and determine the cutoff values that best predict TTM outcomes in patients with large hemispheric infarction. We retrospectively reviewed brain computed tomography (CT) scans of 21 patients with large hemispheric infarctions, who were treated with TTM. We excluded 4 patients whose CT scans were inadequate for evaluation, which left 17 patients. We divided the patients into success and failure groups. TTM failure was defined as death or the need for decompressive hemicraniectomy (DHC) after TTM. Infarction size was measured as the total restricted area in diffusion-weighted imaging that was performed on admission. CT scans were obtained on the first and second days after TTM initiation and then every 2 days. We measured septum pellucidum shifts (SPS) and pineal gland shifts (PGS) on CT scans. The median time from symptom onset to TTM initiation was 14.5 hours. Ten patients were successfully treated with TTM, six patients died, and one patient underwent a DHC. Initial infarction sizes were not significantly different between the success and failure groups (p = 0.529), but the SPS and PGS at 36-72 hours after TTM initiation were (mean SPS: 5.0 vs. 14.9 mm, p = 0.001; mean PGS: 2.3 vs. 7.9 mm, p = 0.001). The sensitivity and negative predictive value for TTM failure caused by cerebral edema (SPS ≥9.25 mm and PGS ≥3.70 mm) at 36-72 hours after TTM initiation were both 100%. The SPS and PGS on CT scans taken 36-72 hours after TTM initiation may help to estimate the effect of TTM on cerebral edema and guide further treatment.

Cerebral Ischemic Reperfusion Injury Following Recanalization of Large Vessel Occlusions

Although stroke has recently dropped to become the nation's fifth leading cause of mortality, it remains the top leading cause of morbidity and disability in the US. Recent advances in stroke treatment, including intravenous fibrinolysis and mechanical thromboembolectomy, allow treatment of a greater proportion of stroke patients than ever before. While intra-arterial fibrinolysis with recombinant tissue plasminogen is an effective for treatment of a broad range of acute ischemic strokes, endovascular mechanical thromboembolectomy procedures treat severe strokes due to large artery occlusions, often resistant to intravenous drug. Together, these procedures result in a greater proportion of revascularized stroke patients than ever before, up to 88% in 1 recent trial (EXTEND-IA). Subsequently, there is a growing need for neurointensivists to develop more effective strategies to manage stroke patients following successful reperfusion. Cerebral ischemic reperfusion injury (CIRI) is defined as deterioration of brain tissue suffered from ischemia that concomitantly reverses the benefits of re-establishing cerebral blood flow following mechanical or chemical therapies for acute ischemic stroke. Herein, we examine the pathophysiology of CIRI, imaging modalities, and potential neuroprotective strategies. Additionally, we sought to lay down a potential treatment approach for patients with CIRI following emergent endovascular recanalization for acute ischemic stroke.

Normothermia and Stroke

OPINION STATEMENT

In the past two decades, there has been much focus on the adverse effect of fever on neurologic outcome, the benefits of hypothermia on functional outcomes, and the interplay of associated complications. Despite decades of experience regarding randomized, safety and feasibility, case-controlled, retrospective studies, there has yet to be a large, randomized, multicenter, clinical trial with the appropriate power to address the potential benefits of targeted temperature modulation compared to hypothermia alone. What remains unanswered is the appropriate timing of initiation, duration, rewarming speed, and depth of targeted temperature management. We learn from the cardiac arrest literature that there is a neuroprotective value to hypothermia and, most recently, near normothermia (36 °C) as well. We have also established that increased depths of cooling are associated with increases in shivering, which warrant more aggressive pharmacologic management. Normothermia also has the advantage of allowing for more rapid clearance of sedating medications and less confounding of neuroprognostication. More difficult to quantify is the increased nursing and patient care complexity associated with moderate hypothermia compared to normothermia. It remains crucial, for those patients who are being considered for hypothermia/normothermia, to be cared for in an experienced ICU, driven under protocol, with aggressive shivering management and an expectation and acceptance of the complications associated with targeted temperature management. If targeted temperature management is not of consideration, then aggressive fever control should be undertaken pharmacologically and non-invasively, as they have been shown to be safe.

Therapeutic hypothermia protocols

The application of targeted temperature management has become common practice in the neurocritical care setting. It is important to recognize the pathophysiologic mechanisms by which temperature control impacts acute neurologic injury, as well as the clinical limitations to its application. Nonetheless, when utilizing temperature modulation, an organized approach is required in order to avoid complications and minimize side-effects. The most common clinically relevant complications are related to the impact of cooling on hemodynamics and electrolytes. In both instances, the rate of complications is often related to the depth and rate of cooling or rewarming. Shivering is the most common side-effect of hypothermia and is best managed by adequate monitoring and stepwise administration of medications specifically targeting the shivering response. Due to the impact cooling can have upon pharmacokinetics of commonly used sedatives and analgesics, there can be significant delays in the return of the neurologic examination. As a result, early prognostication posthypothermia should be avoided.

Controversies in Out of Hospital Cardiac Arrest?

Cardiac arrest is a major cause of morbidity and mortality and accounts for nearly 500,000 deaths annually in the United States. In patients suffering out-of-hospital cardiac arrest, survival is less than 15%, with considerable regional variation. Although most deaths occur during the initial resuscitation, an increasing proportion occur in patients hospitalized after initially successful resuscitation. In these patients, the significant subsequent morbidity and mortality is due to "post cardiac arrest syndrome." Until recently, most single interventions have yielded little improvement in rates of survival; however, there is growing recognition that optimal treatment strategies during the postresuscitation phase may improve outcomes.

Extended Use of Hypothermia in Elderly Patients with Malignant Cerebral Edema as an Alternative to Hemicraniectomy

Background and Purpose

The use of decompressive hemicraniectomy (DHC) for the treatment of malignant cerebral edema can decrease mortality rates. However, this benefit is not sufficient to justify its use in elderly patients. We investigated the effects of therapeutic hypothermia (TH) on safety, feasibility, and functional outcomes in elderly patients with malignant middle cerebral artery (MCA) infarcts.

Methods

Elderly patients 60 years of age and older with infarcts affecting more than two-thirds of the MCA territory were included. Patients who could not receive DHC were treated with TH. Hypothermia was started within 72 hours of symptom onset and was maintained for a minimum of 72 hours with a target temperature of 33°C. Modified Rankin Scale (mRS) scores at 3 months following treatment and complications of TH were used as functional outcomes.

Results

Eleven patients with a median age of 76 years and a median National Institutes of Health Stroke Scale score of 18 were treated with TH. The median time from symptom onset to initiation of TH was 30.3±23.0 hours and TH was maintained for a median of 76.7±57.1 hours. Shivering (100%) and electrolyte imbalance (82%) were frequent complications. Two patients died (18%). The mean mRS score 3 months following treatment was 4.9±0.8.

Conclusions

Our results suggest that extended use of hypothermia is safe and feasible for elderly patients with large hemispheric infarctions. Hypothermia may be considered as a therapeutic alternative to DHC in elderly individuals. Further studies are required to validate our findings.

Neurocritical Care of Emergent Large-Vessel Occlusion: The Era of a New Standard of Care

Acute ischemic stroke continues to be one of the leading causes of morbidity and mortality worldwide. Recent advances in mechanical thrombectomy techniques combined with prereperfusion computed tomographic angiography for patient selection have revolutionized stroke care in the past year. Peri- and postinterventional neurocritical care of the patient who has had an emergent large-vessel occlusion is likely an equally important contributor to the outcome but has been relatively neglected. Critical periprocedural management issues include streamlining care to speed intervention, blood pressure optimization, reversal of anticoagulation, management of agitation, and selection of anesthetic technique (ie, general vs monitored anesthesia care). Postprocedural critical care issues that might modulate neurological outcome include blood pressure and glucose optimization, avoidance of fever or hyperoxia, fluid and nutritional management, and early integration of rehabilitation into the intensive care unit setting. In this review, we sought to lay down an evidence-based strategy for patients with acute ischemic stroke undergoing emergent endovascular reperfusion.

Glibenclamide enhances the effects of delayed hypothermia after experimental stroke in rats

In order to evaluate whether glibenclamide can extend the therapeutic window during which induced hypothermia can protect against stroke, we subjected adult male Sprague-Dawley rats to middle cerebral artery occlusion (MCAO). We first verified the protective effects of hypothermia induced at 0, 2, 4 or 6h after MCAO onset, and then we assessed the effects of the combination of glibenclamide and hypothermia at 6, 8 or 10h after MCAO onset. At 24h after MCAO, we assessed brain edema, infarct volume, modified neurological severity score, Evans Blue leakage and expression of Sulfonylurea receptor 1 (SUR1) protein and pro-inflammatory factors. No protective effects were observed when hypothermia was induced too long after MCAO. At 6h after MCAO onset, hypothermia alone failed to decrease cerebral edema and infarct volume, but the combination of glibenclamide and hypothermia decreased both. The combination also improved neurological outcome, ameliorated blood-brain barrier damage and decreased levels of COX-2, TNF-α and IL-1β. These results suggest that glibenclamide enhances and extends the therapeutic effects of delayed hypothermia against ischemia stroke, potentially by ameliorating blood-brain barrier damage and declining levels of pro-inflammatory factors.

Revisiting Cerebral Postischemic Reperfusion Injury: New Insights in Understanding Reperfusion Failure, Hemorrhage, and Edema

Cerebral postischemic reperfusion injury is defined as deterioration of ischemic brain tissue that parallels and antagonizes the benefits of restoring cerebral circulation after therapeutic thrombolysis for acute ischemic stroke. To understand the paradox of injury caused by treatment, we first emphasize the phenomenon in which recanalization of an occluded artery does not lead to tissue reperfusion. Additionally, no-reflow after recanalization may be due to injury of the neurovascular unit, distal microthrombosis, or both, and certainly worsens outcome. We examine the mechanism of molecular and sub-cellular damage in the neurovascular unit, notably oxidative stress, mitochondrial dysfunction, and apoptosis. At the level of the neurovascular unit, which mediates crosstalk between the damaged brain and systemic responses in blood, we summarize emerging evidence demonstrating that individual cell components play unique and cumulative roles that lead to damage of the blood–brain barrier and neurons. Furthermore, we review the latest developments in establishing a link between the immune system and microvascular dysfunction during ischemic reperfusion. Progress in assessing reperfusion injury has also been made, and we review imaging studies using various magnetic resonance imaging modalities. Lastly, we explore potential treatment approaches, including ischemic preconditioning, postconditioning, pharmacologic agents, and hypothermia.

The use of targeted temperature management for elevated intracranial pressure

The use of hypothermia for treatment of intracranial hypertension is controversial, despite no other medical therapy demonstrating consistent improvements in morbidity or mortality. Much of this may be the result of negative results from randomized controlled trials. However, the patients selected for these trials may have obscured the results in the populations most likely to benefit. Further, brain injury does not behave uniformly, not even within a diagnosis. Therefore, therapies may have more benefit in some diseases, less in others. This review focuses on the effect on outcome of intracranial hypertension in common disease processes in the neurocritical care unit, and identifies who is most likely to benefit from the use of hypothermia.

Drug-induced hypothermia in stroke models: does it always protect?

Ischemic stroke is a common neurological disorder lacking a cure. Recent studies show that therapeutic hypothermia is a promising neuroprotective strategy against ischemic brain injury. Several methods to induce therapeutic hypothermia have been established; however, most of them are not clinically feasible for stroke patients. Therefore, pharmacological cooling is drawing increasing attention as a neuroprotective alternative worthy of further clinical development. We begin this review with a brief introduction to the commonly used methods for inducing hypothermia; we then focus on the hypothermic effects of eight classes of hypothermia-inducing drugs: the cannabinoids, opioid receptor activators, transient receptor potential vanilloid, neurotensins, thyroxine derivatives, dopamine receptor activators, hypothermia-inducing gases, adenosine, and adenine nucleotides. Their neuroprotective effects as well as the complications associated with their use are both considered. This article provides guidance for future clinical trials and animal studies on pharmacological cooling in the setting of acute stroke.

Therapeutic effects of pharmacologically induced hypothermia against traumatic brain injury in mice

Preclinical and clinical studies have shown therapeutic potential of mild-to-moderate hypothermia for treatments of stroke and traumatic brain injury (TBI). Physical cooling in humans, however, is usually slow, cumbersome, and necessitates sedation that prevents early application in clinical settings and causes several side effects. Our recent study showed that pharmacologically induced hypothermia (PIH) using a novel neurotensin receptor 1 (NTR1) agonist, HPI-201 (also known as ABS-201), is efficient and effective in inducing therapeutic hypothermia and protecting the brain from ischemic and hemorrhagic stroke in mice. The present investigation tested another second-generation NTR1 agonist, HPI-363, for its hypothermic and protective effect against TBI. Adult male mice were subjected to controlled cortical impact (CCI) (velocity=3 m/sec, depth=1.0 mm, contact time=150 msec) to the exposed cortex. Intraperitoneal administration of HPI-363 (0.3 mg/kg) reduced body temperature by 3-5°C within 30-60 min without triggering a shivering defensive reaction. An additional two injections sustained the hypothermic effect in conscious mice for up to 6 h. This PIH treatment was initiated 15, 60, or 120 min after the onset of TBI, and significantly reduced the contusion volume measured 3 days after TBI. HPI-363 attenuated caspase-3 activation, Bax expression, and TUNEL-positive cells in the pericontusion region. In blood-brain barrier assessments, HPI-363 ameliorated extravasation of Evans blue dye and immunoglobulin G, attenuated the MMP-9 expression, and decreased the number of microglia cells in the post-TBI brain. HPI-363 decreased the mRNA expression of tumor necrosis factor-α and interleukin-1β (IL-1β), but increased IL-6 and IL-10 levels. Compared with TBI control mice, HPI-363 treatments improved sensorimotor functional recovery after TBI. These findings suggest that the second generation NTR-1 agonists, such as HPI-363, are efficient hypothermic-inducing compounds that have a strong potential in the management of TBI.

Recommendations for the management of cerebral and cerebellar infarction with swelling: a statement for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

There are uncertainties surrounding the optimal management of patients with brain swelling after an ischemic stroke. Guidelines are needed on how to manage this major complication, how to provide the best comprehensive neurological and medical care, and how to best inform families facing complex decisions on surgical intervention in deteriorating patients. This scientific statement addresses the early approach to the patient with a swollen ischemic stroke in a cerebral or cerebellar hemisphere.

METHODS

The writing group used systematic literature reviews, references to published clinical and epidemiology studies, morbidity and mortality reports, clinical and public health guidelines, authoritative statements, personal files, and expert opinion to summarize existing evidence and to indicate gaps in current knowledge. The panel reviewed the most relevant articles on adults through computerized searches of the medical literature using MEDLINE, EMBASE, and Web of Science through March 2013. The evidence is organized within the context of the American Heart Association framework and is classified according to the joint American Heart Association/American College of Cardiology Foundation and supplementary American Heart Association Stroke Council methods of classifying the level of certainty and the class and level of evidence. The document underwent extensive American Heart Association internal peer review.

RESULTS

Clinical criteria are available for hemispheric (involving the entire middle cerebral artery territory or more) and cerebellar (involving the posterior inferior cerebellar artery or superior cerebellar artery) swelling caused by ischemic infarction. Clinical signs that signify deterioration in swollen supratentorial hemispheric ischemic stroke include new or further impairment of consciousness, cerebral ptosis, and changes in pupillary size. In swollen cerebellar infarction, a decrease in level of consciousness occurs as a result of brainstem compression and therefore may include early loss of corneal reflexes and the development of miosis. Standardized definitions should be established to facilitate multicenter and population-based studies of incidence, prevalence, risk factors, and outcomes. Identification of patients at high risk for brain swelling should include clinical and neuroimaging data. If a full resuscitative status is warranted in a patient with a large territorial stroke, admission to a unit with neurological monitoring capabilities is needed. These patients are best admitted to intensive care or stroke units attended by skilled and experienced physicians such as neurointensivists or vascular neurologists. Complex medical care includes airway management and mechanical ventilation, blood pressure control, fluid management, and glucose and temperature control. In swollen supratentorial hemispheric ischemic stroke, routine intracranial pressure monitoring or cerebrospinal fluid diversion is not indicated, but decompressive craniectomy with dural expansion should be considered in patients who continue to deteriorate neurologically. There is uncertainty about the efficacy of decompressive craniectomy in patients ≥60 years of age. In swollen cerebellar stroke, suboccipital craniectomy with dural expansion should be performed in patients who deteriorate neurologically. Ventriculostomy to relieve obstructive hydrocephalus after a cerebellar infarct should be accompanied by decompressive suboccipital craniectomy to avoid deterioration from upward cerebellar displacement. In swollen hemispheric supratentorial infarcts, outcome can be satisfactory, but one should anticipate that one third of patients will be severely disabled and fully dependent on care even after decompressive craniectomy. Surgery after a cerebellar infarct leads to acceptable functional outcome in most patients.

CONCLUSIONS

Swollen cerebral and cerebellar infarcts are critical conditions that warrant immediate, specialized neurointensive care and often neurosurgical intervention. Decompressive craniectomy is a necessary option in many patients. Selected patients may benefit greatly from such an approach, and although disabled, they may be functionally independent.

Endovascular therapeutic hypothermia for acute ischemic stroke: ICTuS 2/3 protocol

Therapeutic hypothermia improves neurological outcome after out-of-hospital cardiac arrest or neonatal hypoxic-ischemic injury. Although supported by preclinical evidence, therapeutic hypothermia for acute stroke remains under study. In the Intravascular Cooling in the Treatment of Stroke (ICTuS) trial, awake stroke patients were successfully cooled using an endovascular cooling catheter and a novel antishivering regimen. In the ICTuS-L study, the combination of endovascular hypothermia and thrombolysis proved feasible; while hypothermia was associated with no increased risk of bleeding complications, there was an increased association with pneumonia. Despite efforts to expedite, cooling began on average six-hours after stroke onset. We designed a novel Phase 2/3 trial to further test the safety of combined thrombolysis and endovascular hypothermia and to determine if the combination shows superiority compared with thrombolysis alone. ICTuS 2 (n = 400) will assess four hypotheses, and if milestones are met, ICTuS 3 (n = 1200) will begin as a seamless continuation for a total sample of 1600 patients. The ICTuS 2 milestones include (1) target temperature reached within six-hours of symptom onset; (2) no increased risk of pneumonia; (3) no increase in signs/symptoms of fluid overload due to chilled saline infusions; and (4) sufficient recruitment to complete the trial on time. The ICTuS 2/3 protocol contains novel features - based on the previous ICTuS and ICTuS-L trials - designed to achieve these milestones. Innovations include scrupulous pneumonia surveillance, intravenous chilled saline immediately after randomization to induce rapid cooling, and a requirement for catheter placement within two-hours of thrombolysis. An Investigational Device Exemption has been obtained and an initial group of sites initiated.

Hypothermia in neurocritical care

Hypothermia has long been recognized as an effective therapy for acute neurologic injury. Recent advances in bedside technology and greater understanding of thermoregulatory mechanisms have made this therapy readily available at the bedside. Critical care management of the hypothermic patient can be divided into 3 phases: induction, maintenance, and rewarming. Each phase has known complications that require careful monitoring. At present, hypothermia has only been shown to be an effective neuroprotective therapy in cardiac arrest survivors. The primary use of hypothermia in the neurocritical care unit is to treat increased intracranial pressure.

Overview of therapeutic hypothermia

OPINION STATEMENT

Therapeutic hypothermia has proven neuroprotective effects in global cerebral ischemia. Indications for hypothermia induction include cardiac arrest and neonatal asphyxia. The two general methods of induced hypothermia are either surface cooling or endovascular cooling. Hypothermia should be induced as early as possible to achieve maximum neuroprotection and edema blocking effect. Endovascular cooling has the benefit of shorter time to reach target temperature but catheter insertion requires expertise and training, which may be a barrier to widespread availability. The optimum method of cooling is yet to be determined but a multimodal approach is necessary to address three phases of cooling: induction, maintentance, and rewarm. Specifying core practitioners who are well-versed in established guidelines can help integrate the multidisciplinary team that is needed to successfully implement cooling protocols. Reducing shivering to make heat exchange more efficient with tighter temperature control enables quicker time to target temperature and avoids rewarming which can lead to inadvertent increase in intracranial pressure and cerebral edema. Promising applications but yet to be determined is whether hypothermia treatment can improve outcomes in acute ischemic stroke or traumatic brain injury.

Use of hypothermia in the intensive care unit

Used for over 3600 years, hypothermia, or targeted temperature management (TTM), remains an ill defined medical therapy. Currently, the strongest evidence for TTM in adults are for out-of-hospital ventricular tachycardia/ventricular fibrillation cardiac arrest, intracerebral pressure control, and normothermia in the neurocritical care population. Even in these disease processes, a number of questions exist. Data on disease specific therapeutic markers, therapeutic depth and duration, and prognostication are limited. Despite ample experimental data, clinical evidence for stroke, refractory status epilepticus, hepatic encephalopathy, and intensive care unit is only at the safety and proof-of-concept stage. This review explores the deleterious nature of fever, the theoretical role of TTM in the critically ill, and summarizes the clinical evidence for TTM in adults.

Cooling in intracerebral hemorrhage (CINCH) trial: protocol of a randomized German-Austrian clinical trial

BACKGROUND

Intracerebral hemorrhage accounts for up to 15% of all strokes and is frequently associated with poor functional outcome and high mortality. So far, there is no clear evidence for a specific therapy, apart from general stroke unit or neurointensive care and management of secondary complications. Promising experimental and pilot clinical data support the use of therapeutic hypothermia after intracerebral hemorrhage.

AIMS

The study aims to determine if therapeutic hypothermia improves survival rates and reduces cerebral lesion volume after large intracerebral hemorrhage compared with conventional treatment.

MATERIAL AND METHODS

The Cooling in IntraCerebral Hemorrhage trial is a prospective, multicenter, interventional, randomized, parallel, two-arm (1 : 1) phase II trial with blinded end-point adjudication. Enrolment: 50 patients (age: 18 to 65 years) with large (25 to 64 ml on cranial computertomography), primary intracerebral hemorrhage of the basal ganglia or thalamus within 6 to 18 h after symptom onset are randomly allocated to therapeutic hypothermia for eight-days or conventional temperature management. In the therapeutic hypothermia group, a target temperature of 35.0°C is achieved by endovascular catheters and followed by slow controlled rewarming. Data analysis is based on the intent-to-treat population. The primary outcome measure of the study is the development in total lesion volume on cranial computertomography (intracerebral hemorrhage plus perihemorrhagic edema on day 8 ± 0.5 and day 1 ± 0.5 after intracerebral hemorrhage) and the mortality after 30 days. Secondary end-points are the in-hospital mortality, mortality, and functional outcome (modified Rankin Scale and Barthel-Index) after 90 and 180 days. Safety measures include any adverse events associated with therapeutic hypothermia.

DISCUSSION

In the face of a lack of evidence-based therapies for patients with large intracerebral hemorrhage, new promising approaches are desperately needed, but need evaluation in randomized controlled trials.

CONCLUSION

The results of Cooling in IntraCerebral Hemorrhage trial are believed to directly influence future therapy of large intracerebral hemorrhage.

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 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.

Therapeutic hypothermia in acute stroke

Treatment of acute stroke is difficult due to the complexity of events triggered by ischemic insult. Current reperfusion strategies are time limited and, alone, may not be sufficient to achieve maximal neurologic outcomes. Therapeutic hypothermia (TH) appears to be a promising neuroprotective therapy, as it affects a wide range of destructive mechanisms occurring in ischemic brain tissue. Animal research has substantiated the use of TH in acute stroke. Human studies utilizing TH in acute stroke have shown trends toward positive effects; however, there have been a variety of measurements and methods making comparisons difficult. The ideal protocol for the use of TH in stroke has not yet been developed and requires determination of optimal depth, duration, and methods of temperature measurement and cooling for acute stroke. The purposes of this article were to (1) discuss the effects of ischemia and reperfusion in acute stroke, (2) discuss how TH can potentially limit neurological injury, and (3) review current literature on the use of hypothermia as a treatment for acute stroke.

Therapeutic targets for neuroprotection in acute ischemic stroke: lost in translation?

The development of a suitable neuroprotective agent to treat ischemic stroke has failed when transitioned to the clinical setting. An understanding of the molecular mechanisms involved in neuronal injury during ischemic stroke is important, but must be placed in the clinical context. Current therapeutic targets have focused on the preservation of the ischemic penumbra in the hope of improving clinical outcomes. Unfortunately, most patients in the ultra-early time windows harbor penumbra but have tremendous variability in the size of the core infarct, the ultimate predictor of prognosis. Understanding this variability may allow for proper patient selection that may better correlate to bench models. Reperfusion therapies are rapidly evolving and have been shown to improve clinical outcomes. The use of neuroprotective agents to prolong time windows prior to reperfusion or to prevent reperfusion injury may present future therapeutic targets for the treatment of ischemic stroke. We review the molecular pathways and the clinical context from which future targets may be identified.

Hyperacute therapies for childhood stroke: a case report and review of the literature

Objective. The optimal management of pediatric patients with arterial ischemic stroke (AIS) is not known. Despite this, goal-oriented, time-sensitive therapies geared to rapid reestablishment of arterial blood flow are occasionally applied with beneficial effects. The inconsistent approach to AIS is in part due to a lack of knowledge and preparedness. Methods. Case report of a 12-year-old male with right middle cerebral artery (MCA) occlusion resulting in dense left hemiplegia and mutism and review of the literature. Intervention(s). Mechanical thrombectomy, intra-arterial administration of rt-PA, vasodilators, and platelet inhibitors, and systemic anticoagulation and subsequent critical care support. Results. Restoration of right MCA blood flow and complete resolution of neurologic deficits. Conclusion. We report the gratifying outcome of treatment of a case of AIS in a pediatric patient treated with hyperacute therapies geared to arterial recanalization and subsequent neurologic critical care and review the pertinent literature. Guidelines for the emergency room management of pediatric AIS from prospective, randomized trials are needed.

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

BACKGROUND AND PURPOSE

Induced hypothermia is a promising neuroprotective therapy. We studied the feasibility and safety of hypothermia and thrombolysis after acute ischemic stroke.

METHODS

Intravenous Thrombolysis Plus Hypothermia for Acute Treatment of Ischemic Stroke (ICTuS-L) was a randomized, multicenter trial of hypothermia and intravenous tissue plasminogen activator in patients treated within 6 hours after ischemic stroke. Enrollment was stratified to the treatment time windows 0 to 3 and 3 to 6 hours. Patients presenting within 3 hours of symptom onset received standard dose intravenous alteplase and were randomized to undergo 24 hours of endovascular cooling to 33°C followed by 12 hours of controlled rewarming or normothermia treatment. Patients presenting between 3 and 6 hours were randomized twice: to receive tissue plasminogen activator or not and to receive hypothermia or not. Results- In total, 59 patients were enrolled. One patient was enrolled but not treated when pneumonia was discovered just before treatment. All 44 patients enrolled within 3 hours and 4 of 14 patients enrolled between 3 to 6 hours received tissue plasminogen activator. Overall, 28 patients randomized to receive hypothermia (HY) and 30 to normothermia (NT). Baseline demographics and risk factors were similar between groups. Mean age was 65.5±12.1 years and baseline National Institutes of Health Stroke Scale score was 14.0±5.0; 32 (55%) were male. Cooling was achieved in all patients except 2 in whom there were technical difficulties. The median time to target temperature after catheter placement was 67 minutes (Quartile 1 57.3 to Quartile 3 99.4). At 3 months, 18% of patients treated with hypothermia had a modified Rankin Scale score of 0 or 1 versus 24% in the normothermia groups (nonsignificant). Symptomatic intracranial hemorrhage occurred in 4 patients (68); all were treated with tissue plasminogen activator <3 hours (1 received hypothermia). Six patients in the hypothermia and 5 in the normothermia groups died within 90 days (nonsignificant). Pneumonia occurred in 14 patients in the hypothermia and in 3 of the normothermia groups (P=0.001). The pneumonia rate did not significantly adversely affect 3 month modified Rankin Scale score (P=0.32).

CONCLUSIONS

This study demonstrates the feasibility and preliminary safety of combining endovascular hypothermia after stroke with intravenous thrombolysis. Pneumonia was more frequent after hypothermia, but further studies are needed to determine its effect on patient outcome and whether it can be prevented. A definitive efficacy trial is necessary to evaluate the efficacy of therapeutic hypothermia for acute stroke.

Predictors for good functional outcome after neurocritical care

Introduction

There are only limited data on the long-term outcome of patients receiving specialized neurocritical care. In this study we analyzed survival, long-term mortality and functional outcome after neurocritical care and determined predictors for good functional outcome.

Methods

We retrospectively investigated 796 consecutive patients admitted to a non-surgical neurologic intensive care unit over a period of two years (2006 and 2007). Demographic and clinical parameters were analyzed. Depending on the diagnosis, we grouped patients according to their diseases (cerebral ischemia, intracranial hemorrhage (ICH), subarachnoid hemorrhage (SAH), meningitis/encephalitis, epilepsy, Guillain-Barré syndrome (GBS) and myasthenia gravis (MG), neurodegenerative diseases and encephalopathy, cerebral neoplasm and intoxication). Clinical parameters, mortality and functional outcome of all treated patients were analyzed. Functional outcome (using the modified Rankin Scale, mRS) one year after discharge was assessed by a mailed questionnaire or telephone interview. Outcome was dichotomized into good (mRS ≤ 2) and poor (mRS ≥ 3). Logistic regression analyses were calculated to determine independent predictors for good functional outcome.

Results

Overall in-hospital mortality amounted to 22.5% of all patients, and a good long-term functional outcome was achieved in 28.4%. The parameters age, length of ventilation (LOV), admission diagnosis of ICH, GBS/MG, and inoperable cerebral neoplasm as well as Therapeutic Intervention Scoring System (TISS)-28 on Day 1 were independently associated with functional outcome after one year.

Conclusions

This investigation revealed that age, LOV and TISS-28 on Day 1 were strongly predictive for the outcome. The diagnoses of hemorrhagic stroke and cerebral neoplasm leading to neurocritical care predispose for functional dependence or death, whereas patients with GBS and MG are more likely to recover after neurocritical care.

Moderate hypothermia prevents cardiac arrest-mediated suppression of drug metabolism and induction of interleukin-6 in rats

OBJECTIVE

Therapeutic hypothermia is being clinically used to reduce neurologic deficits after cardiac arrest (CA). Patients receiving hypothermia after CA receive a wide-array of medications. During hypothermia, drug metabolism is markedly reduced. Little, however, is known about the impact of hypothermia on drug metabolism after rewarming. The objective of this study was to examine the effect of CA and hypothermia on the functional regulation of two major drug metabolizing cytochrome P450 (CYP) isoforms.

DESIGN

Laboratory investigation.

SETTING

University pharmacy school and animal research facility.

SUBJECTS

Thirty-six male Sprague-Dawley rats.

INTERVENTIONS

Hypothermia was induced via surface cooling in a rat CA model and maintained for 3 hrs. Animals were killed at 5 or 24 hrs and liver was analyzed for hepatic activity and mRNA expression of CYP3A2 and CYP2E1. Plasma interleukin-6 (IL-6) concentrations were determined. The effect of IL-6 on pregnane X receptor-mediated transcription of the rat CYP3A2 promoter was evaluated via luciferase reporter in HepG2 cells.

MEASUREMENTS AND MAIN RESULTS

At 24 hrs after CA a decrease in CYP3A2 and CYP2E1 activity was observed, 55.7% +/- 12.8% and 46.8% +/- 29.7% of control, respectively (p < 0.01). CA decreased CYP3A2 mRNA (p < 0.05), but not CYP2E1 mRNA. Expression of other pregnane X receptor target enzymes and transporter genes were similarly down-regulated. CA also produced an approximately ten-fold increase in plasma IL-6. CA-mediated inhibition of CYP3A2 and CYP2E1 was attenuated by hypothermia, as was the increase in IL-6. Furthermore, IL-6 attenuated pregnane X receptor-mediated transcription of the CYP3A2 promoter.

CONCLUSIONS

CA produces CYP3A2 down-regulation at 24 hrs, potentially via IL-6 effects on pregnane X receptor-mediated transcription. Also, hypothermia attenuates the CA-mediated down-regulation, thereby normalizing drug metabolism after rewarming.

Induced hypothermia in acute ischemic stroke

BACKGROUND

Induced hypothermia is a promising neuroprotective treatment for acute ischemic stroke. Data from both global and focal ischemia animal models have been encouraging. However, only a few small clinical studies have investigated its use in humans.

OBJECTIVE

To review the background, possible mechanisms of action, and the preclinical and clinical data supporting the neuroprotective role of induced hypothermia following acute ischemic stroke.

METHODS

A literature search was performed using the PubMed database. Only papers in English were reviewed.

RESULTS/CONCLUSIONS

Induced hypothermia is effective as a neuroprotectant in animal models of acute ischemic stroke. Its multimodal mechanism of action makes it a very attractive method of neuroprotection. Although human studies suggest it is safe and feasible, larger randomized controlled trials are necessary to address clinical efficacy and to refine the methods and parameters of induced hypothermia protocols.