Preoperative-induced mild hypothermia attenuates neuronal damage in a rat subdural hematoma model

Hypothermia for Patients Requiring Evacuation of Subdural Hematoma: A Multicenter Randomized Clinical Trial

Background

Hypothermia is neuroprotective in some ischemia–reperfusion injuries. Ischemia–reperfusion injury may occur with traumatic subdural hematoma (SDH). This study aimed to determine whether early induction and maintenance of hypothermia in patients with acute SDH would lead to decreased ischemia–reperfusion injury and improve global neurologic outcome.

Methods

This international, multicenter randomized controlled trial enrolled adult patients with SDH requiring evacuation of hematoma within 6 h of injury. The intervention was controlled temperature management of hypothermia to 35 °C prior to dura opening followed by 33 °C for 48 h compared with normothermia (37 °C). Investigators randomly assigned patients at a 1:1 ratio between hypothermia and normothermia. Blinded evaluators assessed outcome using a 6-month Glasgow Outcome Scale Extended score. Investigators measured circulating glial fibrillary acidic protein and ubiquitin C-terminal hydrolase L1 levels.

Results

Independent statisticians performed an interim analysis of 31 patients to assess the predictive probability of success and the Data and Safety Monitoring Board recommended the early termination of the study because of futility. Thirty-two patients, 16 per arm, were analyzed. Favorable 6-month Glasgow Outcome Scale Extended outcomes were not statistically significantly different between hypothermia vs. normothermia groups (6 of 16, 38% vs. 4 of 16, 25%; odds ratio 1.8 [95% confidence interval 0.39 to ∞], p = .35). Plasma levels of glial fibrillary acidic protein (p = .036), but not ubiquitin C-terminal hydrolase L1 (p = .26), were lower in the patients with favorable outcome compared with those with unfavorable outcome, but differences were not identified by temperature group. Adverse events were similar between groups.

Conclusions

This trial of hypothermia after acute SDH evacuation was terminated because of a low predictive probability of meeting the study objectives. There was no statistically significant difference in functional outcome identified between temperature groups.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12028-021-01334-w.

Anatomical Correlates and Surgical Considerations for Localized Therapeutic Hypothermia Application in Cochlear Implantation Surgery

Application of localized, mild therapeutic hypothermia during cochlear implantation (CI) surgery is feasible for residual hearing preservation.

Therapeutic hypothermia and targeted temperature management for traumatic brain injury: Experimental and clinical experience

Traumatic brain injury (TBI) is a worldwide medical problem, and currently, there are few therapeutic interventions that can protect the brain and improve functional outcomes in patients. Over the last several decades, experimental studies have investigated the pathophysiology of TBI and tested various pharmacological treatment interventions targeting specific mechanisms of secondary damage. Although many preclinical treatment studies have been encouraging, there remains a lack of successful translation to the clinic and no therapeutic treatments have shown benefit in phase 3 multicenter trials. Therapeutic hypothermia and targeted temperature management protocols over the last several decades have demonstrated successful reduction of secondary injury mechanisms and, in some selective cases, improved outcomes in specific TBI patient populations. However, the benefits of therapeutic hypothermia have not been demonstrated in multicenter randomized trials to significantly improve neurological outcomes. Although the exact reasons underlying the inability to translate therapeutic hypothermia into a larger clinical population are unknown, this failure may reflect the suboptimal use of this potentially powerful therapeutic in potentially treatable severe trauma patients. It is known that multiple factors including patient recruitment, clinical treatment variables, and cooling methodologies are all important in yielding beneficial effects. High-quality multicenter randomized controlled trials that incorporate these factors are required to maximize the benefits of this experimental therapy. This article therefore summarizes several factors that are important in enhancing the beneficial effects of therapeutic hypothermia in TBI. The current failures of hypothermic TBI clinical trials in terms of clinical protocol design, patient section, and other considerations are discussed and future directions are emphasized.

Establishment of an ideal time window model in hypothermic-targeted temperature management after traumatic brain injury in rats

Although hypothermic-targeted temperature management (HTTM) holds great potential for the treatment of traumatic brain injury (TBI), translation of the efficacy of hypothermia from animal models to TBI patientshas no entire consistency. This study aimed to find an ideal time window model in experimental rats which was more in accordance with clinical practice through the delayed HTTM intervention. Sprague-Dawley rats were subjected to unilateral cortical contusion injury and received therapeutic hypothermia at 15mins, 2 h, 4 h respectively after TBI. The neurological function was evaluated with the modified neurological severity score and Morris water maze test. The brain edema and morphological changes were measured with the water content and H&E staining. Brain sections were immunostained with antibodies against DCX (a neuroblast marker) and GFAP (an astrocyte marker). The apoptosis levels in the ipsilateral hippocampi and cortex were examined with antibodies against the apoptotic proteins Bcl-2, Bax, and cleaved caspase-3 by the immunofluorescence and western blotting. The results indicated that each hypothermia therapy group could improve neurobehavioral and cognitive function, alleviate brain edema and reduce inflammation. Furthermore, we observed that therapeutic hypothermia increased DCX expression, decreased GFAP expression, upregulated Bcl-2 expression and downregulated Bax and cleaved Caspase-3 expression. The above results suggested that HTTM at 2h or even at 4h post-injury revealed beneficial brain protection similarly, despite the best effect at 15min post-injury. These findings may provide relatively ideal time window models, further making the following experimental results more credible and persuasive.

Subdural hematoma decompression model: A model of traumatic brain injury with ischemic-reperfusional pathophysiology: A review of the literature

The prognosis for patients with traumatic brain injury (TBI) with subdural hematoma (SDH) remains poor. In accordance with an increasing elderly population, the incidence of geriatric TBI with SDH is rising. An important contributor to the neurological injury associated with SDH is the ischemic damage which is caused by raised intracranial pressure (ICP) producing impaired cerebral perfusion. To control intracranial hypertension, the current management consists of hematoma evacuation with or without decompressive craniotomy. This removal of the SDH results in the immediate reversal of global ischemia accompanied by an abrupt reduction of mass lesion and an ensuing reperfusion injury. Experimental models can play a critical role in improving our understanding of the underlying pathophysiology and in exploring potential treatments for patients with SDH. In this review, we describe the epidemiology, pathophysiology and clinical background of SDH.

Therapeutic hypothermia and targeted temperature management in traumatic brain injury: Clinical challenges for successful translation

The use of therapeutic hypothermia (TH) and targeted temperature management (TTM) for severe traumatic brain injury (TBI) has been tested in a variety of preclinical and clinical situations. Early preclinical studies showed that mild reductions in brain temperature after moderate to severe TBI improved histopathological outcomes and reduced neurological deficits. Investigative studies have also reported that reductions in post-traumatic temperature attenuated multiple secondary injury mechanisms including excitotoxicity, free radical generation, apoptotic cell death, and inflammation. In addition, while elevations in post-traumatic temperature heightened secondary injury mechanisms, the successful implementation of TTM strategies in injured patients to reduce fever burden appear to be beneficial. While TH has been successfully tested in a number of single institutional clinical TBI studies, larger randomized multicenter trials have failed to demonstrate the benefits of therapeutic hypothermia. The use of TH and TTM for treating TBI continues to evolve and a number of factors including patient selection and the timing of the TH appear to be critical in successful trial design. Based on available data, it is apparent that TH and TTM strategies for treating severely injured patients is an important therapeutic consideration that requires more basic and clinical research. Current research involves the evaluation of alternative cooling strategies including pharmacologically-induced hypothermia and the combination of TH or TTM approaches with more selective neuroprotective or reparative treatments. This manuscript summarizes the preclinical and clinical literature emphasizing the importance of brain temperature in modifying secondary injury mechanisms and in improving traumatic outcomes in severely injured patients. This article is part of a Special Issue entitled SI:Brain injury and recovery.