Decompressive Craniectomy

Does decompressive craniectomy improve outcomes in patients with diffuse traumatic brain injury?

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Every year in Australia, 1000 people are admitted to intensive care units with severe traumatic brain injury, mostly as a result of motor vehicle accidents.1 Despite high standards of prehospital and medical care, 50% of these people either die or survive with severe lifelong disability.2 Most of the survivors with severe disability are young men aged in their mid 20s;2 they cannot return to work and will never be able to live independently. The cost of severe traumatic brain injury in human terms is huge, and in economic terms has been recently independently calculated to be $4.8 billion every year in Australia.1 In the United States, the annual economic burden of traumatic brain injury is $60 billion.3

Half of patients with severe traumatic brain injury have haematomas that may require neurosurgical evacuation; management of these patients before and after surgery is not controversial. However, about 10% of patients have diffuse brain injury,4 and also have persistent brain swelling that cannot be effectively controlled in intensive care units by airway management, mechanical ventilation, intracranial pressure monitoring, heavy anaesthesia, resuscitation fluids, osmotherapy, and drainage of cerebrospinal fluid from ventricular catheters. Over the past decade, management of these patients has been shifting in many centres from barbiturate therapy, and sometimes hypothermia, to decompressive craniectomy5 — a well established neurosurgical procedure in which a large piece of skull bone is removed (stored for 1–2 months, and then replaced) to enable better control of intracranial pressure and a more rapid decrease of sedation, with the ultimate goal of improving patients’ long-term functional outcomes. About 20 case series of adult patients from many countries have reported mainly favourable results from this procedure.6 However, all suffer from a lack of prospective randomised control groups and of objective blinded outcome assessment at defined time points.

To objectively assess decompressive craniectomy for the first time and to establish its true efficacy in adult patients with traumatic brain injury, intensivists and neurosurgeons in Australia, New Zealand and Saudi Arabia collaborated between 2003 and 2010 to conduct the Decompressive Craniectomy (DECRA) randomised trial. The results of the DECRA trial have recently been published.7 This was the first randomised trial of any neurosurgical technique to be completed in complex adult neurotrauma patients. Patients were randomly assigned to receive decompressive craniectomy plus standard care (maximised intensive care therapies, which could include barbiturate anaesthesia) or standard care alone. The study found that early decompressive craniectomy clearly and dramatically achieved its short-term goals: it decreased intracranial pressure, markedly decreased medical therapies required for intracranial pressure, shortened mechanical ventilation time, and shortened stay in the intensive care unit by 5 days compared with the standard care group. The dramatic short-term effects meant that the study was difficult to complete because neurosurgeons and intensivists were aware of group allocation, could see the early benefits, and increasingly preferred to conduct early surgery rather than recruit patients to the trial.

However, despite these positive short-term effects, the findings in relation to patients’ eventual functional outcome, measured carefully at 6 months, were startling and the reverse of what had been expected. There were 19% more patients with poor functional outcomes (odds ratio, 2.21; 95% CI, 1.14–4.26; P = 0.02) and 23% more survivors with severe disability in the decompressive craniectomy group compared with patients who received standard care alone.

The cause of these poor outcomes is speculative. They may have related to the surgery itself or to surgical complications (including hydrocephalus), but surgical complications seem an unlikely explanation given that the rates overall were less than those reported in published case series. A more likely explanation is that “axonal stretch” that occurred during swelling of the brain outside the skull through the craniectomy defect8 exacerbated brain injury in a way that has not previously been described in humans and was not anticipated. Multimodal magnetic resonance imaging may enable confirmation of this. We might now coin the term “brain volutrauma”, analogous to the “lung volutrauma” observed in mechanically ventilated patients with acute lung injury.

A second ongoing randomised trial — the Randomised Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of Intracranial Pressure (RESCUEicp) — is addressing similar questions in the United Kingdom and Europe. The RESCUEicp trial also includes patients with brain haematomas and intervenes at a slightly higher intracranial pressure threshold,9 so the results will be complementary to the DECRA trial and are likely to be equally important.

What is unequivocal is that functional outcomes of future patients with severe diffuse traumatic brain injury in Australia and New Zealand can be substantially improved by choosing best intensive care medical and surgical therapies, based on established guidelines,10 without early decompressive craniectomy, despite increases in intracranial pressure that may be concerning to clinicians. The role of decompressive craniectomy as a rescue therapy in the context of very high intracranial pressure has not been resolved by this study, but is now clearly uncertain. It is also unequivocal that the Australian health care system will save many tens of millions of dollars annually when the less invasive treatment regimen is chosen. Although careful cost–benefit analyses are urgently required (and can be done using existing databases), it is already clear from independent costing analyses, which confirmed that most of the traumatic brain injury cost burden relates to rehabilitation costs of survivors with severe disability,1 that the savings to Australia of choosing intensive medical therapies instead of craniectomy in appropriate patients will be greater than $100 million annually. Savings in the US and Europe are likely to be proportionately greater.

Finally, the DECRA trial illustrates with new clarity that carefully designed randomised controlled trials are the only way to correctly advance clinical practice, even in complex, critically ill patients, and despite the clear inherent difficulties of such trials.11 Recent calls for “comparative effectiveness research” in neurosurgery,12 based on aggregations of non-randomised databases, do not represent a valid substitute. In the DECRA trial, a collaborative network of clinician-investigators (the Australian and New Zealand Intensive Care Society Clinical Trials Group), which was supported by the National Health and Medical Research Council (NHMRC) and co-funders, unfettered by industry, and motivated by a strong desire to improve the quality of outcomes in critically ill patients, enabled the trial to be supported to completion and to influence clinical practice for the better. These are the essential ingredients needed to make meaningful improvements in health care.

source: Canadian journal of medicine

Clinical Value of Decompressive Craniectomy

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Patients with a variety of intracranial disorders — including traumatic brain injury, stroke, subarachnoid hemorrhage, intracerebral hemorrhage, and brain tumors — often present with a progressive increase in intracranial pressure, leading to clinical deterioration and ultimately to death. Medical therapy1 can help to mitigate such increases in pressure, but despite the use of the best available measures, intracranial hypertension becomes life-threatening in some patients. More than a century ago, it was suggested that it might be beneficial to “decompress the brain by widely opening the skull to decrease the pressure”2 in patients with severe traumatic brain injury. This procedure, called decompressive craniectomy, has been shown to decrease intracranial pressure, but since there is no evidence of an association with a better clinical outcome, the procedure is considered optional.3

In the past 15 years, the use of decompressive craniectomy has increased substantially. There has also been a tremendous increase in the number of articles that have been published on the subject, mainly retrospective reviews of a limited number of cases. A PubMed search identified 143 articles that were published on this topic for a variety of intracranial disorders in 2009 and 2010.

The list of publications is much shorter, however, when only randomized, controlled trials are considered. In the field of traumatic brain injury, the results of only one small, prospective, randomized trial have been published.4 This trial involving 27 children showed promising results in favor of decompressive craniectomy. However, the surgical procedure that was used (bitemporal decompression without opening of the dura) is not the standard approach.

In this issue of the Journal, Cooper et al. report the results of the Decompressive Craniectomy (DECRA) trial,5 which investigated the role of early decompressive craniectomy in adults with severe head injury (Glasgow Coma Scale score of 3 to 8). Patients with refractory intracranial hypertension (defined as an intracranial pressure higher than 20 mm Hg for more than 15 minutes despite medical therapy) were randomly assigned either to receive standard care or to undergo standard care plus bifrontotemporoparietal decompression craniectomy. The study showed a significant decrease in intracranial pressure in patients in the surgical group, as was expected. However, clinical outcomes, as assessed by scores on the Extended Glasgow Outcome Scale, were worse in the surgical group than in the standard-care group, a finding that went against expectations.

There are a couple of important concerns regarding this otherwise valuable study. First, most neurosurgeons and intensivists dealing with traumatic brain injury will not consider decompressive craniectomy in patients who have an intracranial pressure of around 20 mm Hg for such a short time. This aggressive approach may be justified in order to decompress the brain as soon as possible, but in patients with diffuse injury without mass lesions, physicians in many centers would use medical therapy for a longer period, leaving decompressive craniectomy as a last resort.

Second, the screening of 3478 patients over a 7-year period to enroll only 155 study patients indicates that the results of this study are limited to a restricted subpopulation of patients with traumatic brain injury. Most of the patients who were excluded from this trial either had mass lesions (for which a different surgical approach might be appropriate) or had successful control of intracranial hypertension with medical management (thus not requiring surgical intervention at all).

An important question arising from the DECRA study is whether it is now appropriate to continue an ongoing trial of craniectomy, called the Randomized Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of Intracranial Pressure (RESCUEicp; Current Controlled Trials number, ISRCTN66202560).6 As of March 16, 2011, a total of 294 patients had been enrolled in this trial, with an enrollment goal of 400 patients. However, the design of RESCUEicp differs from that of the DECRA study in some important ways. In RESCUEicp, patients are randomly assigned either to undergo craniectomy or to receive standard care (including the use of barbiturates) when maximal medical therapy cannot control intracranial pressure, with a threshold of 25 mm Hg (rather than 20 mm Hg) for more than 1 to 12 hours (rather than 15 minutes) at any time after injury. In addition, in RESCUEicp, as compared with the DECRA study, previous evacuation of a hematoma is allowed before randomization, and the permitted surgical techniques include both bifrontal decompression and unilateral wide decompression. The primary end point is the assessment of outcome at discharge and at 6 months. Thus, because of such differences in trial design, it seems that RESCUEicp should continue.

Another important question is, How do the DECRA and RESCUEicp studies relate to the real practice of decompression in patients with traumatic brain injury? As noted above, the exclusion criteria for the DECRA study were such that the data do not apply to the majority of patients. In a multicenter study involving 729 patients with intradural mass lesions after traumatic injury,7 we found that about one third of patients undergoing surgery for an intracranial hematoma also required a decompressive procedure. In most of these cases, the decompression was unilateral and associated with hematoma evacuation. Such patients are not considered at all in the DECRA study and are only partially included in the RESCUEicp study. We therefore probably need another study of early decompression associated with hematoma evacuation, as has been suggested previously,8 since this procedure is a common one.

The main lesson from the DECRA study is that surgical reduction of intracranial pressure by the technique that was used by the investigators does not necessarily result in better outcomes for patients and indeed appears to worsen them in at least some circumstances. However, it is important that the procedure not be simply abandoned on the basis of these data. Rather, we must think more carefully about the risks and benefits of the decompressive craniectomy before performing the procedure and must work to define appropriate clinical settings for this procedure.

source: NEJM