Christopher R. P. Lind

Observed versus Predicted Outcome for Decompressive Craniectomy: A Population-Based Study

A number of studies have shown that decompressive craniectomy can reduce intracranial pressure and may improve outcome for patients with severe head injury. This cohort study assessed the long-term outcome of neurotrauma patients who had a decompressive craniectomy for severe head injury in Western Australia between 2004 and 2008. The web-based outcome prediction model developed by the CRASH trial collaborators was applied to the cohort. Predicted outcome and observed outcome were compared. Characteristics of outcome between those who had had a unilateral and those who had had a bilateral decompressive procedure were compared. All complications were recorded. Among a total of 1,786 adult neurotrauma patients admitted during the study period, 147 patients (8.2%) had a decompressive craniectomy. A significant proportion of patients who required unilateral (37.3%) and bilateral (46.5%) craniectomy were able to return to work or study at 18 months after the injury. The patients who required bilateral craniectomy more likely to be associated with an unfavorable outcome (Glasgow Outcome Scale score >or=3) than those who had unilateral craniectomy (odds ratio 4.42; 95% confidence interval 1.16,16.81; p = 0.029), after adjusting for the timing of surgery, mechanism of injury, and the predicted risk of unfavorable outcome. The functional outcome after either unilateral or bilateral decompressive craniectomy was significantly better than that predicted by the CRASH head injury prediction model when the predicted risk was less than 80%. This study has demonstrated that in Western Australia decompressive craniectomy is a relatively common surgical procedure for the management of neurotrauma. A significant proportion of patients had a better-than-predicted long-term functional outcome.

The Retrospective Application of a Prediction Model to Patients Who Have Had a Decompressive Craniectomy for Trauma

There is currently a resurgence of interest in the use of decompressive craniectomy. As the procedure is used more frequently, there may be an increasing number of patients surviving a severe traumatic brain injury with severe neurological impairment. The aim of this study was to determine if we could predict those cases that fall into this category. We used the web-based prediction model prepared by the CRASH collaborators and applied it to a cohort of patients who had a decompressive craniectomy in 2006 and 2007 at the two major trauma hospitals in Western Australia. All clinical and radiological data were reviewed and entered into the model, and predicted outcome and actual outcome were compared. Our analysis indicated that a significant cut-off point appeared at which the model predicted a 75% risk of an unfavorable outcome at 6 months; 19 of 27 patients with CRASH scores <75% returned to work, whereas none of the 14 patients with higher scores achieved this degree of rehabilitation at 18 months. Statistical analysis of the outcomes in our cohort confirmed that the CRASH model reliably predicted unfavorable outcome. This study demonstrated that our ability to predict poor outcome has improved.

What can be learned from the DECRA study

BACKGROUND There has been a resurgence of interest in the use of decompressive craniectomy for severe traumatic brain injury (TBI). Numerous studies have shown that the procedure can consistently reduce intracranial pressure (ICP), and a significant number of patients achieve a good long-term functional recovery. However, there has been debate regarding clinical indications and patient selection. METHODS The DECRA (Decompressive Craniectomy in Patients with Severe Traumatic Brain Injury) study compared patients who underwent early decompressive craniectomy for diffuse TBI with patients who received standard medical therapy. Of patients, 70% in the craniectomy group had an unfavourable outcome versus 51% in the standard care group (odds ratio 2.21 [95% confidence interval 1.14-4.26]; P=0.02). Based on these results, the authors concluded that decompressive craniectomy was associated with more unfavorable outcomes and that by adopting standard medical therapy rather than surgical decompression the health care system would save millions of dollars. These conclusions are not really supported by closer examination of the basic data. There were problems with randomization such that the patients in the surgical arm appeared to have sustained a more severe primary TBI, the ICP threshold of >20 mm Hg for >15 minutes did not reflect clinical practice, and there was a high crossover rate from the standard care arm to the surgical arm. Because of these problems, the DECRA trial has received a great deal of criticism, and some authorities have claimed that the results should have no influence on clinical practice. This claim is perhaps unfair, and an alternative interpretation is offered. RESULTS Overall, the results of the DECRA study showed that a relatively transient and mild increase in ICP (>20 mm Hg for 15 minutes as recruitment criterion) does not imply that there is significant ongoing secondary brain injury, and any potential improvement obtained by surgical decompression may well be offset by surgical morbidity. CONCLUSIONS The role of decompressive craniectomy when ICP continues to increase ≥20 mm Hg remains to be established. The ongoing RESCUEicp (Randomised Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of Intra-Cranial Pressure) study hopes to address this issue.

Accuracy of Postoperative Computed Tomography and Magnetic Resonance Image Fusion for Assessing Deep Brain Stimulation Electrodes

BACKGROUND:Knowledge of the anatomic location of the deep brain stimulation (DBS) electrode in the brain is essential in quality control and judicious selection of stimulation parameters. Postoperative computed tomography (CT) imaging coregistered with preoperative magnetic resonance imaging (MRI) is commonly used to document the electrode location safely. The accuracy of this method, however, depends on many factors, including the quality of the source images, the area of signal artifact created by the DBS lead, and the fusion algorithm. OBJECTIVE:To calculate the accuracy of determining the location of active contacts of the DBS electrode by coregistering postoperative CT image to intraoperative MRI. METHODS:Intraoperative MRI with a surrogate marker (carbothane stylette) was digitally coregistered with postoperative CT with DBS electrodes in 8 consecutive patients. The location of the active contact of the DBS electrode was calculated in the stereotactic frame space, and the discrepancy between the 2 images was assessed. RESULTS:The carbothane stylette significantly reduces the signal void on the MRI to a mean diameter of 1.4 ± 0.1 mm. The discrepancy between the CT and MRI coregistration in assessing the active contact location of the DBS lead is 1.6 ± 0.2 mm, P < .001 with iPlan (BrainLab AG, Erlangen, Germany) and 1.5 ± 0.2 mm, P < .001 with Framelink (Medtronic, Minneapolis, Minnesota) software. CONCLUSION:CT/MRI coregistration is an acceptable method of identifying the anatomic location of DBS electrode and active contacts.

Statins may not protect against vasospasm in subarachnoid haemorrhage

Statins have been shown in two recent small phase I/II trials to be associated with a marked reduction in clinical and transcranial Doppler (TCD) evidence of vasospasm after aneurysmal subarachnoid haemorrhage (SAH). The purpose of this study was to assess the clinical impact of this treatment in a larger number of patients. Fifty-eight individuals were treated in the year before, and 72 patients treated in the year after, the introduction of a 2week course of 40mg/day pravastatin therapy for SAH. Statins did not result in reduced TCD velocities, clinical or angiographic vasospasm, or improvements in global outcome at the time of hospital discharge. A measurable reduction in the rates of vasospasm was expected, based on the size of the effect of statin therapy in the previous small studies. There remains significant uncertainty as to the role of statins in preventing vasospasm after SAH.

Neurotrauma and the RUB: where tragedy meets ethics and science

Decompressive craniectomy is a technically straightforward procedure whereby a large section of the cranium is temporarily removed in cases where the intracranial pressure is dangerously high. While its use has been described for a number of conditions, it is increasingly used in the context of severe head injury. As the use of the procedure increases, a significant number of patients may survive a severe head injury who otherwise would have died. Unfortunately some of these patients will be left severely disabled; a condition likened to the RUB, an acronym for the Risk of Unacceptable Badness. Until recently it has been difficult to predict this outcome, however an accurate prediction model has been developed and this has been applied to a large cohort of patients in Western Australia. It is possible to compare the predicted outcome with the observed outcome at 18 months within this cohort. By using predicted and observed outcome data this paper considers the ethical implications in three cases of differing severity of head injury in view of the fact that it is possible to calculate the RUB for each case.

Cost-effectiveness of decompressive craniectomy as a lifesaving rescue procedure for patients with severe traumatic brain injury.

BACKGROUND Decompressive craniectomy has been traditionally used as a lifesaving rescue procedure for patients with refractory intracranial hypertension after severe traumatic brain injury (TBI), but its cost-effectiveness remains uncertain. METHODS Using data on length of stay in hospital, rehabilitation facility, procedural costs, and Glasgow Outcome Scale (GOS) up to 18 months after surgery, the average total hospital costs per life-year and quality-adjusted life-year (QALY) were calculated for patients who had decompressive craniectomy for TBI between 2004 and 2010 in Western Australia. The Corticosteroid Randomisation After Significant Head Injury prediction model was used to quantify the severity of TBI. RESULTS Of the 168 patients who had 18-month follow-up data available after the procedure, 70 (42%) achieved a good outcome (GOS-5), 27 (16%) had moderate disability (GOS-4), 34 (20%) had severe disability (GOS-3), 5 (3%) were in vegetative state (GOS-2), and 32 (19%) died (GOS-1). The hospital costs increased with the severity of TBI and peaked when the predicted risk of an unfavorable outcome was about 80%. The average cost per life-year gained (US

A randomized controlled trial comparing autologous cranioplasty with custom-made titanium cranioplasty

671,000 per life-year) and QALY (US

Magnetic resonance imaging of the subthalamic nucleus for deep brain stimulation

682,000 per QALY) increased substantially and became much more than the usual acceptable cost-effective limit (US

The Future of Decompressive Craniectomy for Diffuse Traumatic Brain Injury

100,000 per QALY) when the predicted risk of an unfavorable outcome was >80%. Changing different underlying assumptions of the analysis did not change the results significantly. CONCLUSIONS Severity of TBI had an important effect on cost-effectiveness of decompressive craniectomy. As a lifesaving procedure, decompressive craniectomy was not cost-effective for patients with extremely severe TBI.