Decompressive Craniectomy for Severe Diffuse TBI
Abstract & Commentary
By Halinder S. Mangat, MD, Assistant Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Mangat reports no financial relationships relevant to this field of study.
Synopsis: Decompressive craniectomy for severe diffuse traumatic brain injury and refractory intracranial hypertension (ICP) reduces ICP but increases unfavorable outcomes.
Sources: Cooper DJ, et al for the DECRA Trial Investigators and the Australian and New Zealand Intensive Care Society Clinical Trials Group. Decompressive craniectomy in diffuse traumatic brain injury. N Engl J Med 2011. DOI: 10.1056/NEJMoa1102077. Servadei F. Clinical value of decompressive craniectomy. New Engl J Med 2011. DOI: 10.1056/nejme1102998.
Decompressive craniectomy is commonly used in the treatment of refractory intracranial hypertension following malignant middle cerebral artery infarction (MCAI), traumatic brain injury (TBI), and occasionally, aneurysmal subarachnoid hemorrhage (SAH). The beneficial effects of early decompressive craniectomy in improving outcomes and reducing mortality has been demonstrated in malignant MCAI.1,2 However, prior to the DECRA trial, no large, randomized clinical trial was completed to study its role in refractory intracranial hypertension following severe TBI.
In this study, the investigators evaluated early (in the first 72 hours) bifrontotemporoparietal craniectomy in the management of refractory intracranial hypertension following diffuse brain injury. Refractory ICP was defined as ICP more than 20 mmHg for more than 15 minutes during any 1 hour. All patients received tier 1 therapies, which included hypertonic saline, mannitol, optimal sedation, neuromuscular paralysis, and CSF diversion. After this stage, patients were randomized to either surgery or tier 2 therapies, which included hypothermia and barbiturates. The investigators screened 3478 patients between the ages of 15 and 59 over 7 years, during which time 155 were enrolled. Patients with GCS between 3 and 8 were included. Exclusions were based on dilated and unreactive pupils, mass lesions requiring surgical intervention, spinal cord injury, and cardiac arrest at scene.
The results show a worse outcome for patients who underwent craniectomy. Unfavorable outcome was 70% in these patients vs. 50% in patients who received standard therapies. While deaths were not higher, more patients had worse functional outcomes after surgery. Surgery, however, lowered ICP, time spent above ICP of 20 mmHg, and improved cerebral perfusion pressure (CPP). It also decreased mechanical ventilation days and days in ICU, but not days in hospital.
Commentary
This trial examines early craniectomy with a lower threshold for definition of intractable intracranial hypertension. The results have been eagerly anticipated and the findings are unexpected. However, it is to be noted that the study tested the benefit of craniectomy in a very small subgroup of severe TBI patients. Only patients with diffuse head injury were included. Patients with mass lesions who comprise a large subgroup of severe head injury patients and frequently require surgical intervention were excluded. The investigators screened 3478 patients and only 155 were eligible for enrollment (4.4%). This is further evidence that this study looked at a small, highly selected subgroup of patients with severe TBI.
Another confounder is the significantly larger percentage of patients in the craniectomy group with bilateral unreactive pupils. Such patients tend to do poorly in spite of all therapies. When correcting for this, the negative effect of craniectomy on outcome disappeared.
Bifrontotemporoparietal craniectomy is a radical procedure. Its effect on cerebral blood flow and metabolism may be detrimental3,4 or beneficial.5 There is the possibility of irreversible metabolic injury in spite of reduction in ICP.4 Decreases in ICP can cause hyperperfusion due to higher CPP and poor autoregulation worsened by decompression.
The study concludes that early craniectomy is not beneficial in treating diffuse head injury. However, as discussed in the accompanying editorial, this should not lead to the abandonment of the surgical procedure until data from other trials are available. We should be circumspect in performing radical craniectomy surgery in diffuse TBI.
The RESCUEicp trial,6 which is still enrolling patients, is studying the effect of last-stage randomization to decompressive craniectomy vs barbiturate coma in refractory intracranial hypertension. This will elucidate the effect of late craniectomy. The trial does not limit enrollment by the underlying nature of brain injury or the type of surgery performed for decompression bifrontal, unilateral, or bilateral and will be more inclusive. An area that still remains to be examined is the potential benefit of primary decompressive craniectomy frequently necessitated by large focal lesions, such as acute subdural hematomas.
References
1. Vahedi K, et al. Sequential-design, multicenter, randomized, controlled trial of early decompressive craniectomy in malignant middle cerebral artery infarction (DECIMAL Trial). Stroke 2007;38:2506-2517.
2. Hofmeijer J, et al. Surgical decompression for space-occupying cerebral infarction (the Hemicraniectomy After Middle Cerebral Artery infarction with Life-threatening Edema Trial [HAMLET]): A multicentre, open, randomized trial. Lancet Neurol 2009;8:326-333.
3. Timofeev I, et al. Effect of decompressive craniectomy on intracranial pressure and cerebrospinal compensation following traumatic brain injury. J Neurosurg 2008;108:66-73.
4. Soustiel JF, et al. Cerebral blood flow and metabolism following decompressive craniectomy for control of increased intracranial pressure. Neurosurgery 2010;67:65-72.
5. Ho CL, et al. Cerebral oxygenation, vascular reactivity, and neurochemistry following decompressive craniectomy for severe traumatic brain injury. J Neurosurg 2008;108:943-949.
6. The RESCUEicp Study. Randomised Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of Intra-cranial Pressure. Available at: www.rescueicp.com. Accessed April 14, 2011.
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