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Targeted temperature management, or therapeutic hypothermia, is a potent neuroprotective approach after ischemic brain injury. Hypothermia should be induced as soon as possible after the onset of acute stroke to assure better outcomes. Accordingly, drugs with a fast-acting hypothermic effect sustainable through the period of emergency transportation to hospital would have clinical advantages. Activation of the transient receptor potential vanilloid-1 (TRPV1) can induce hypothermia. Our immunohistochemical investigations confirmed that TRPV1 was distributed to perivascular and periventricular regions of the rat brain, where TRPV1 can be easily detected by TRPV1 agonists. An endogenous TRPV1 selective agonist, N -oleoyldopamine (OLDA), and a synthetic antagonist, AMG 9810, were injected intraperitoneally into healthy adult male Wister rats, and brain and core temperatures and gross motor activities were monitored. Comparison with baseline temperatures showed that TRPV1 injection immediately induced mild hypothermia ( p  < 0.05 in brain and p  < 0.01 in body), and AMG 9810 induced immediate mild hyperthermia (not significant). However, the OLDA-induced hypothermia did not decrease lesion volume after middle carotid artery occlusion in rats. Relative to vehicle, OLDA yielded poorer outcomes and AMG 9810 yielded better outcomes in neurological scores and lesion size. Our study showed that, as an agonist of TRPV1, OLDA has suitable hypothermia-inducing properties, but did not decrease lesion volume. Therefore, the search for novel TRPV1 agonists and/or antagonists providing hypothermia and neuroprotection should continue. Further investigations should also target OLDA-induced transient hypothermia combined with long-term hypothermia maintenance with surface cooling, which mimics the anticipated clinical use of this class of drug.

Background and purpose: Therapeutic hypothermia (TH), or targeted temperature management (TTM), is a classic treatment option for reducing inflammation and potentially other destructive processes across a wide range of pathologies, and has been successfully used in numerous disease states. The ability for TH to improve neurological outcomes seems promising for inflammatory injuries but has yet to demonstrate clinical benefit in the intracerebral hemorrhage (ICH) patient population. Minimally invasive ICH evacuation also presents a promising option for ICH treatment with strong preclinical data but has yet to demonstrate functional improvement in large randomized trials. The biochemical mechanisms of action of ICH evacuation and TH appear to be synergistic, and thus combining hematoma evacuation with cooling therapy could provide synergistic benefits. The purpose of this working group was to develop consensus recommendations on optimal clinical trial design and outcomes for the use of therapeutic hypothermia in ICH in conjunction with minimally invasive ICH evacuation. Methods: An international panel of experts on the intersection of critical-care TH and ICH was convened to analyze available evidence and form a consensus on critical elements of a focal cooling protocol and clinical trial design. Three focused sessions and three full-group meetings were held virtually from December 2020 to February 2021. Each meeting focused on a specific subtopic, allowing for guided, open discussion. Results: These recommendations detail key elements of a clinical cooling protocol and an outline for the roll-out of clinical trials to test and validate the use of TH in conjunction with hematoma evacuation as well as late-stage protocols to improve the cooling approach. The combined use of systemic normothermia and localized moderate (33.5 °C) hypothermia was identified as the most promising treatment strategy. Conclusions: These recommendations provide a general outline for the use of TH afterminimally invasive ICH evacuation. More research is needed to further refine the use and combination of these promising treatment paradigms for this patient population. [ABSTRACT FROM AUTHOR]

Background: Therapeutic hypothermia (TH) is an established treatment after cardiac arrest and growing evidence supports its use as neuroprotective treatment in stroke. Only few and heterogeneous studies exist on the effect of hypothermia in subarachnoid hemorrhage (SAH). A novel approach of early and prolonged TH and its influence on key complications in poor-grade SAH, vasospasm and delayed cerebral ischemia (DCI) was evaluated. Methods: This observational matched controlled study included 36 poor-grade (Hunt and Hess Scale >3 and World Federation of Neurosurgical Societies Scale >3) SAH patients. Twelve patients received early TH (<48 h after ictus), mild (35°C), prolonged (7 ± 1 days) and were matched to 24 patients from the prospective SAH database. Vasospasm was diagnosed by angiography, macrovascular spasm serially evaluated by Doppler sonography and DCI was defined as new infarction on follow-up CT. Functional outcome was assessed at 6 months by modified Rankin Scale (mRS) and categorized as favorable (mRS score 0-2) versus unfavorable (mRS score 3-6) outcome. Results: Angiographic vasospasm was present in 71.0% of patients. TH neither influenced occurrence nor duration, but the degree of macrovascular spasm as well as peak spastic velocities were significantly reduced (p < 0.05). Frequency of DCI was 87.5% in non-TH vs. 50% in TH-treated patients, translating into a relative risk reduction of 43% and preventive risk ratio of 0.33 (95% CI 0.14-0.77, p = 0.036). Favorable functional outcome was twice as frequent in TH-treated patients 66.7 vs. 33.3% of non-TH (p = 0.06). Conclusion: Early and prolonged TH was associated with a reduced degree of macrovascular spasm and significantly decreased occurrence of DCI, possibly ameliorating functional outcome. TH may represent a promising neuroprotective therapy possibly targeting multiple pathways of DCI development, notably macrovascular spasm, which strongly warrants further evaluation of its clinical impact. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Rationale Cooling reduced infarct size and improved neurological outcomes in animal studies modeling ischemic stroke, and also improved outcome in randomized clinical trials in patients with hypoxic-ischemic brain injury after cardiac arrest. Cooling awake patients with ischemic stroke has been shown feasible in phase II clinical trials. Primary aim To determine whether systemic cooling to a target body temperature between 34·0 and 35·0°C, started within six-hours of symptom onset and maintained for 24 h, improves functional outcome at three-months in patients with acute ischemic stroke. Design International, multicenter, phase III, randomized, open-label clinical trial with blinded outcome assessment in 1500 patients aged 18 years or older with acute ischemic stroke and a National Institutes of Health Stroke Scale score of 6 up to and including 18. In patients randomized to hypothermia, cooling to a target body temperature of 34-35°C will be started within six-hours after symptom onset with rapid intravenous infusion of refrigerated normal saline or a surface cooling technique and maintained for 24 h with a surface or endovascular technique. Patients randomized to hypothermia will receive pethidine and buspirone to prevent shivering and discomfort. Primary outcome Score on the modified Rankin Scale at 91 days, as analyzed with ordinal logistic regression and expressed as a common odds ratio. Discussion With 750 patients per intervention group, this trial has 90% power to detect 7% absolute improvement at the 5% significance level. The full trial protocol is available at . Identifier: NCT01833312. [ABSTRACT FROM AUTHOR]

Rationale Although decompressive hemicraniectomy clearly reduces mortality in severe space-occupying middle cerebral artery infarction (so-called malignant middle cerebral artery infarction), every fifth patient still dies in the acute phase and every third patient is left with moderate to severe disability. Therapeutic hypothermia is a neuroprotective and antiedematous treatment option that has shown promising effects in severe stroke. A combination of both treatment strategies may have the potential to further reduce mortality and morbidity in malignant middle cerebral artery infarction, but needs evaluation of its efficacy within the setting of a randomized clinical trial. Aims The DEcompressive surgery Plus hypo THermia for Space- Occupying Stroke ( DEPTH-SOS) trial aims to investigate safety and feasibility of moderate therapeutic hypothermia (33° C ± 1) over at least 72 h in addition to early decompressive hemicraniectomy (≤48 hours after symptom onset) in patients with malignant middle cerebral artery infarction. Design The DEcompressive surgery Plus hypo THermia for Space- Occupying Stroke is a prospective, multicenter, open, two-arm (1:1) comparative, randomized, controlled trial. Study outcomes The primary end-point is mortality at day 14. The secondary end-points include functional outcome at day 14 and at 12 months follow-up, and complications related to hypothermia. Discussion The results of this trial will provide data on safety and feasibility of moderate hypothermia in addition to decompressive hemicraniectomy in malignant middle cerebral artery infarction. Furthermore, efficacy data on early mortality and long-term functional outcome will be obtained, forming the basis of subsequent trials. [ABSTRACT FROM AUTHOR]

Background: Prehospital cooling of acute stroke patients would be ideal when associated with minor or no side effects. Therefore, we evaluated a cooling cap for the surface of head and cervical regions in awake volunteers. Methods: 10 healthy volunteers were treated by external cooling for 190 min using a gel-based cooling device. Vital signs, rectal temperature, tympanic temperature, the extent of shivering and individual perception of frostiness and discomfort were measured. Results: All participants (median age 35 years) successfully completed the treatment and experienced only mild to moderate discomfort. No serious adverse events and no shivering were noticed. There was a significant drop in the tympanic temperature to 34.68°C (difference from baseline: 1.7°C, 95% CI: 0.61-2.7°C, p = 0.001), in the rectal temperature to 36.65°C (difference from baseline: 0.65°C, 95% CI: 0.06-1.2°C, p = 0.019) and in the heart rate (difference from baseline: 15 beats/min, 95% CI: 0.63-30 beats/min, p = 0.035). Conclusion: Treatment with the cooling device was well tolerated by all participants. The technique had measurable effects on core body temperature (rectal) and tympanic temperature (may reflect temperature at the external ear and skin rather than intracranial). It can be considered as a simple therapeutic approach to patients with suspected stroke in the prehospital setting. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Clinical data clearly show that elevated body temperature contributes to an unfavorable outcome after ischemic and hemorrhagic stroke. Two promising therapeutic strategies arise from this observation: (1) treatment of fever aiming to sustain normothermia and (2) induced hypothermia, targeting core body temperatures below 36.5°C. A limited number of studies investigated antipyretic strategies after acute stroke and their results were rather disappointing in terms of clinical efficacy. For that reason, it remains unproven, whether sufficient fever treatment improves functional outcome. On the other hand, strong experimental evidence supports neuroprotective effects of induced hypothermia after stroke. Yet, clinical data on this topic remain preliminary and rely on a limited number of patients, mostly enrolled in nonrandomized trials. Therefore, induced hypothermia may be considered safe and feasible after ischemic stroke, but little can be said regarding efficacy. This review summarizes the data, both on fever treatment and induced hypothermia following stroke, starting with a synopsis of the most important experimental investigations, leading to the latest clinical trials. Given the promising data and the lack of successful acute neuroprotective therapies available thus far, suggestions are given for future investigation on both topics. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Therapeutic hypothermia is a means of neuroprotection well established in the management of acute ischemic brain injuries such as anoxic encephalopathy after cardiac arrest and perinatal asphyxia. As such, it is the only neuroprotective strategy for which there is robust evidence for efficacy. Although there is overwhelming evidence from animal studies that cooling also improves outcome after focal cerebral ischemia, this has not been adequately tested in patients with acute ischemic stroke. There are still some uncertainties about crucial factors relating to the delivery of hypothermia, and the resolution of these would allow improvements in the design of phase III studies in these patients and improvements in the prospects for successful translation. In this study, we discuss critical issues relating first to the targets for therapy including the optimal depth and duration of cooling, second to practical issues including the methods of cooling and the management of shivering, and finally, of factors relating to the design of clinical trials. Consideration of these factors should inform the development of strategies to establish beyond doubt the place of hypothermia in the management of acute ischemic stroke. [ABSTRACT FROM AUTHOR]

Thrombolysis (T) is limited by reperfusion-associated injury and the short therapeutic window after stroke onset. The present study investigates whether hypothermia alone or in combination with thrombolysis has beneficial effects after experimental thromboembolic stroke. Wistar rats (n = 60) were subjected to thromboembolic occlusion (TE) of the middle cerebral artery (MCA). Thrombolysis (T) was performed with intravenous recombinant tissue-plasminogen activator (rt-PA) 1 h (early T) or 3 h (late T) after TE. Hypothermia (Hy) was applied for 4 h at 33°C started 1 h after TE. Experimental groups included control (C), early thrombolysis (ET), late thrombolysis (LT), hypothermia (Hy), early thrombolysis plus hypothermia (ET+Hy), and late thrombolysis plus hypothermia (LT+Hy). Animals were investigated by MRI and silver infarct staining (SIS) to assess the cerebral infarct size. All animals of group Hy survived, in contrast to 40% in group C (P < 0.05). ET+HY and LT+Hy showed a trend towards better survival as compared to ET and LT alone. PWI parameters were not significantly different between ET versus ET+HY and LT versus LT+Hy, but rt-PA administration led to improved cerebral perfusion in MRI. Significant differences in infarct volumes (T2/SIS) were found after 24 h in all treatment groups versus the control group (P < 0.05). The lesion volume calculated from T2 was significantly smaller in ET (16% ± 5%), ET+Hy (10 ± 4%), and LT+Hy (20% ± 9%) after 5.5 h (10.8% ± 4.8%) versus C (42% ± 15%), (P < 0.05).These data indicate that hypothermia improves survival and decreases infarct volume. However, there were no significant differences between the use of rt-PA alone or in combination with hypothermia. Further studies are needed to confirm these effects, also several days after stroke onset. [Copyright &y& Elsevier]

Objective: Observational studies suggest that infections are a common complication of therapeutic hypothermia. We performed a systematic review and meta-analysis of randomized trials to examine the risk of infections in patients treated with hypothermia. Data Sources: PubMed, Embase, and the Cochrane Central Register of Controlled Trials were systematically searched for eligible studies up to October 1, 2012. Study Selection: We included randomized controlled clinical trials of therapeutic hypothermia induced in adults for any indication, which reported the prevalence of infection in each treatment group. Data Extraction: For each study, we collected information about the baseline characteristics of patients, cooling strategy, and infections. Data Synthesis: Twenty-three studies were identified, which included 2,820 patients, of whom 1,398 (49.6%) were randomized to hypothermia. Data from another 31 randomized trials, involving 4,004 patients, could not be included because the occurrence of infection was not reported with sufficient detail or not at all. The risk of bias in the included studies was high because information on the method of randomization and definitions of infections lacked in most cases, and assessment of infections was not blinded. In patients treated with hypothermia, the prevalence of all infections was not increased (rate ratio, 1.21 [95% CI, 0.95-1.54]), but there was an increased risk of pneumonia and sepsis (risk ratios, 1.44 [95% CI, 1.10-1.90]; 1.80 [95% CI, 1.04-3.10], respectively). Conclusion: The available evidence, subject to its limitations, strongly suggests an association between therapeutic hypothermia and the risk of pneumonia and sepsis, whereas no increase in the overall risk of infection was observed. All future randomized trials of hypothermia should report on this important complication. [ABSTRACT FROM AUTHOR]