Hypothermia treatment for traumatic brain injury: a systematic review and meta-analysis

Hypothermia for traumatic head injury

BACKGROUND

Hypothermia has been used in the treatment of head injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials.

OBJECTIVES

To estimate the effect of mild hypothermia for traumatic head injury on mortality and long-term functional outcome complications.

SEARCH STRATEGY

We searched the Injuries Group Specialised Register, Current Controlled Trials MetaRegister of trials, Zetoc, Web of Knowledge; Science Citation Index [expanded], CENTRAL, MEDLINE and EMBASE. We handsearched conference proceedings and checked reference lists of relevant articles. The search was updated on 23 May 2008.

SELECTION CRITERIA

Randomised controlled trials of hypothermia to a maximum of 35 degrees C for at least 12 hours versus control in patients with any closed traumatic head injury requiring hospitalisation. Two authors independently assessed all trials.

DATA COLLECTION AND ANALYSIS

Data on death, Glasgow Outcome Scale and pneumonia were sought and extracted, either from published material or by contacting the investigators. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for each trial on an intention-to-treat basis.

MAIN RESULTS

We found 22 trials with a total of 1409 randomised patients. Twenty trials involving 1382 patients reported deaths. There were fewer deaths in patients treated with hypothermia than in the control group (OR 0.76, 95% CI 0.60 to 0.97). Eight trials with good allocation concealment showed a non-significant reduction in the likelihood of death for patients treated with hypothermia (OR 0.96, 95% CI 0.68 to 1.35). Twenty trials involving 1382 patients reported data on unfavourable outcomes (death, vegetative state or severe disability). Patients treated with hypothermia were less likely to have an unfavourable outcome than those in the control group (OR 0.69, 95% CI 0.55 to 0.86). Eight trials with good allocation concealment showed a non-significant reduction in the likelihood of unfavourable outcome for patients treated with hypothermia (OR 0.79, 95% CI 0.57 to 1.08). Hypothermia treatment was associated with an increase in odds of pneumonia but this increase was not statistically significant for trials with good allocation concealment (3 trials, 69 patients, OR 1.06, 95% CI 0.38 to 2.97).

AUTHORS' CONCLUSIONS

Hypothermia may be effective in reducing death and unfavourable outcomes for traumatic head injured patients, but significant benefit was only found in low quality trials. Low quality trials have a tendency to overestimate the treatment effect. The high quality trials found some statistically non-significant benefit of hypothermia which could be due to the play of chance. Hypothermia may increase the risk of pneumonia. Due to uncertainties in its effects, hypothermia should only be given to patients taking part in a randomised controlled trial with good allocation concealment.

Acute brain injury and therapeutic hypothermia in the PICU: A rehabilitation perspective

Acquired brain injury from traumatic brain injury, cardiac arrest (CA), stroke, and central nervous system infection is a leading cause of morbidity and mortality in the pediatric population and reason for admission to inpatient rehabilitation. Therapeutic hypothermia is the only intervention shown to have efficacy from bench to bedside in improving neurological outcome after birth asphyxia and adult arrhythmia-induced CA, thought to be due to its multiple mechanisms of action. Research to determine if therapeutic hypothermia should be applied to other causes of brain injury and how to best apply it is underway in children and adults. Changes in clinical practice in the hospitalized brain-injured child may have effects on rehabilitation referral practices, goals and strategies of therapies offered, and may increase the degree of complex medical problems seen in children referred to inpatient rehabilitation.

A review of selective hypothermia in the management of traumatic brain injury

Object

Traumatic brain injury (TBI) remains a significant cause of morbidity and death in the US and worldwide. Resuscitative systemic hypothermia following TBI has been established as an effective neuroprotective treatment in multiple studies in animals and humans, although this intervention carries with it a significant risk profile as well. Selective, or preferential, methods of inducing cerebral hypothermia have taken precedence over the past few years in order to minimize systemic adverse effects. In this report, the authors explore the current methods available for inducing selective cerebral hypothermia following TBI and review the literature regarding the results of animal and human trials in which these methods have been implemented.

Methods

A search of the PubMed archive (National Library of Medicine) and the reference lists of all relevant articles was conducted to identify all animal and human studies pertaining to the use of selective brain cooling, selective hypothermia, preferential hypothermia, or regional hypothermia following TBI.

Results

Multiple methods of inducing selective cerebral hypothermia are currently in the experimental phases, including surface cooling, intranasal selective hypothermia, transarterial or transvenous endovascular cooling, extraluminal vascular cooling, and epidural cerebral cooling.

Conclusions

Several methods of conferring preferential neuroprotection via selective hypothermia currently are being tested. Class I prospective clinical trials are required to assess the safety and efficacy of these methods.

Time-dependent alterations of cholinergic markers after experimental traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of death and disability. Cognitive deficits are believed to be connected with impairments of the cholinergic system. The present study was conducted to evaluate the cholinergic system in a model of focal brain injury with special attention to the time course of posttraumatic events in critical brain regions. Three groups of male Sprague-Dawley rats (post-TBI survival time: 2 h, 24 h and 72 h) were subjected to sham-operation (control) or controlled cortical impact injury. Receptor densities were determined on frozen ipsilateral sagittal brain sections with [(3)H]epibatidine (nicotinic acetylcholine receptors) and [(3)H]QNB (muscarinic acetylcholine receptors). The density of the vesicular acetylcholine transporter (vAChT) was evaluated with (-)[(3)H]vesamicol. Compared to control, vAChT was lowered (up to 50%) at each time point after trauma, with reductions in olfactory tubercle, basal forebrain, motor cortex, putamen, thalamic and hypothalamic areas and the gigantocellular reticular nucleus. Time-dependent reductions of about 20% of nAChR-density in the thalamus, hypothalamus, olfactory tubercle, gigantocellular reticular nucleus and motor cortex were observed post-TBI at 24 and 72 h. The same brain regions showed reductions of mAChR at 24 and 72 h after trauma with additional decreases in the corpus callosum, basal forebrain and anterior olfactory nucleus. In conclusion, cholinergic markers showed significant time-dependent impairments after TBI. Considering the role of the cholinergic system for cognitive processes in the brain, it seems likely that these impairments contribute to clinically relevant cognitive deficits.