Reproduced from Hutchinson et al.6 Copyright © 2023 Massachusetts Medical Society. Reprinted with permission.
Within this trial involving adult patients with traumatic ASDHs requiring surgical evacuation, there were two cohorts of patients; the first were those randomised intraoperatively to either craniotomy or craniectomy, and secondly, the observational cohort, who did not meet the eligibility criteria for randomisation but who underwent surgery and followed up. In the randomised cohort, we found no significant difference across GOSE outcomes between the craniotomy (bone flap replaced) and DC (bone flap left out) at 12 months.
There were significant differences in the functional outcome of patients between the DC and craniotomy groups at both 6 and 12 months in the observed cohort, but these patients had significantly different baselines, with the DC group being younger, with more extracranial injuries, lower GCS and more likely to have had parenchymal lesions and traumatic subarachnoid haemorrhages. This would reflect what might be expected in current clinical practice in that those patients with more severe brain injuries requiring surgery often have the bone flap left out.
To our knowledge, there are no universally accepted criteria that predict the development of postoperative brain swelling and elevated ICP in this setting. Systematic reviews of the literature have identified no other randomised trials, and conclusions have been limited due to confounding by indication, with more severely injured patients undergoing craniectomy more frequently than craniotomy in non-randomised studies.44,45 Therefore, the role of a pre-emptive DC in this setting is not known and has been identified as a research priority.3
The two previously published multicentre trials of DC examined its role as a secondary treatment for post-traumatic intracranial hypertension. The Decompressive Craniectomy in Diffuse Traumatic Brain Injury trial reported similar mortality between early craniectomy and medical management, with worse outcomes in survivors in the surgical group.46 The Randomised Evaluation of Surgery with Craniectomy for Uncontrollable Elevation of Intracranial Pressure trial found a substantial mortality reduction with last-tier DC and a wide range of outcomes in survivors.47,48
Although the present trial found no significant difference in mortality or GOSE outcomes between the DC and the craniotomy groups, additional cranial operations within 2 weeks after randomisation were performed more frequently in the craniotomy group (and most of them were DC for brain swelling). However, patients in the DC group experienced more wound-related complications and surgical site infections.
Although the null hypothesis of no difference between the two groups cannot be formally rejected, the trial may have practical implications. If the bone flap can be replaced without compressing the brain, surgeons should consider doing so, as opposed to performing a pre-emptive DC. These findings may not be relevant for resource-limited or military settings, where an upfront craniectomy is often used due to absence of sophisticated ICU facilities for postoperative care.49,50
Limitations
Reproduced from Hutchinson et al.6 © 2023 Massachusetts Medical Society. Reprinted with permission.
First, the clinicians caring for patients were not blinded to trial group assignments. However, outcome adjudication was performed by personnel who were unaware of the group assignments. Second, 8.8% of patients allocated to craniotomy had a craniectomy, and 5.4% of patients allocated to craniectomy had a craniotomy. This intraoperative non-adherence with allocation did not influence the primary analysis, which was based on the ITT principle. Third, 36 patients (8%) who were randomised were not included in the final analysis due to consent withdrawal and/or loss to follow-up. However, the sample size of the trial allowed for a loss to follow-up up to 10%. Finally, the trial did not formally examine other surgical techniques, such as a floating/hinge craniotomy, removal of contusions that may have a role to play in this setting.
Generalisability
In cases where replacing the bone flap is a feasible option, these results will help guide the surgeon’s decisions. Not replacing the bone usually requires future skull reconstruction, requiring further operation and the risks of associated complications.
These patients often require extensive periods of rehabilitation, and now with clear evidence that the decision of replacing the bone flap in relevant cases does not result in worse outcomes is very useful in the overall management of these patients, both in the acute management and in the longer-term rehabilitation planning.
Patient and public involvement
There was a PPI lead who was also a co-applicant for this project, with a personal experience of critical illness, TBI and rehabilitation, and had a wide experience of research and clinical trials. There was engagement throughout, both during developing the application and protocol as well as through the study. They were involved in reviewing the patient-facing documentation as well as being involved in the running of the study.
Equality, diversity and inclusion
This was an international study with participating sites and patients from many different cultural and religious backgrounds. Patients who were enrolled in this study had suffered a TBI and sustained an ASDH requiring an operation to evacuate it. As our eligible study population was dependent on uncontrollable factors, there was no discrimination, and equal opportunities of neurosurgical care was available for all participants.
Recommendations for future research
- Evaluation of the timing and material of cranial reconstruction on functional recovery.
- Long-term outcome following DC.
Implications for future work
In those patients who have undergone a decompressive craniectomy, the optimal time for cranial reconstruction is not yet known, further research is required and a RCT is planned to help improve the evidence base. The current cranial reconstruction registry in the UK captures operative details of cranial reconstruction surgery with a short 30-day follow-up. Expansion of this registry to record details from the DC with longer-term functional and quality-of-life follow-up will allow for an increased understanding of the recovery and long-term outcomes for this cohort of patients. In this trial, the ‘within-trial’ health economic analysis was sufficient for informing the efficient use of healthcare resources. However, in the treatment of ASDH, it is likely that evaluations of future interventions may cover situations where one intervention is associated with increased short-term costs and be more effective than a comparator. For good decision-making in these cases, it would be important to have reliable and credible long-term data to inform long-term modelling. This model may be able to be incorporated into the cranial reconstruction registry, a prospective registry following patients’ trajectory of recovery after decompression and how the cranioplasty influences such recovery. Being able to closely monitor healthcare resources will be an invaluable addition to this resource.