What is the effect of surgical decompression on death or disability in people who have developed brain swelling after a stroke?
Most strokes are caused by blockage of a blood vessel to the brain (ischaemic stroke), which is a major cause of death and disability worldwide. This blockage prevents the oxygen-carrying blood from supplying the brain, and part of the brain being supplied by this vessel begins to die (infarct). Over the following 24 to 48 hours, the damaged brain begins to swell. Sometimes the swelling can be very dramatic, causing a rise in the pressure inside the skull which can lead to the surrounding brain being affected and rapidly progressing to death.
Surgical decompression can help relieve the pressure by creating a large enough hole in the skull and tissue layers around the affected brain (decompressive craniectomy). Recent studies suggest that early use of this treatment after a large stroke can prevent death or disability in survivors. Early evidence only studied the use of this technique in younger patients; however, more recent studies have begun to address its use in older patients. We wanted to find out whether the use of surgical decompression is better or worse than standard medical management alone in people who have had a large stroke.
In July 2022, we searched the literature for randomised controlled trials (a type of study where participants are randomly assigned to one of two or more treatment groups) that compared outcomes for stroke patients who were treated with early surgical decompression compared to those who were treated without surgery. We found nine trials with a total of 526 participants, of which 13 participants were not included in the final analysis because they were either lost to follow-up or did not follow the trial instructions. We therefore considered 248 participants who received early surgical decompression and 265 participants who received medical treatment alone after their stroke. The trials generally selected people with severe strokes with significant impairments who did not have any previous severe illnesses or disabilities. Two trials recruited patients up to 80 years of age, and one trial only included patients above 60 years old. Six trials treated patients within 48 hours of when their stroke was first noted.
Surgical decompression improved outcomes in people with large strokes when compared to medical treatment alone. The surgical decompression group had a significantly reduced chance of death and a significantly reduced rate of death or severe disability compared to the group receiving medical treatment alone. Using the more encompassing term 'moderate disability', we found there was also a reduced rate of death or moderate disability in the surgical group compared to the group receiving medical treatment alone. There was no difference between groups in the proportion of survivors with severe disability; however, there was a fair degree of uncertainty surrounding this result.
The harms of surgery, or any intervention including medical management, were not reported in a consistent manner across the included trials, therefore we could draw no meaningful conclusions on potential harms. When participants were categorised by age below or above 60 years, the results showed that older patients in general have a poorer prognosis than younger ones, although participants above the age of 60 also benefited from decompressive surgery.
Quality of the evidence
The overall quality of the evidence in this review was high, therefore we have a high degree of confidence in the main findings of this review.
Surgical decompression improves outcomes in the management of malignant oedema after acute ischaemic stroke, including a considerable reduction in death or severe disability (mRS > 4) and a reduction in death or moderate disability (mRS > 3). Whilst there is evidence that this positive treatment effect is present in patients > 60 years old, it is important to take into account that these patients have a poorer prospect of functional survival independent of this treatment effect. In interpreting these results it must also be considered that the data demonstrating benefit are drawn from a unique patient subset with profound neurological deficit, reduced level of consciousness, and no pre-morbid disability or severe comorbidity.
Large territory middle cerebral artery (MCA) ischaemic strokes account for around 10% of all ischaemic strokes and have a particularly devastating prognosis when associated with malignant oedema. Progressive cerebral oedema starts developing in the first 24 to 48 hours of stroke ictus with an associated rise in intracranial pressure. The rise in intracranial pressure may eventually overwhelm compensatory mechanisms leading to a cascading secondary damage to surrounding unaffected parenchyma. This downward spiral can rapidly progress to death or severe neurological disability. Early decompressive craniectomy to relieve intracranial pressure and associated tissue shift can help ameliorate this secondary damage and improve outcomes. Evidence has been accumulating of the benefit of early surgical decompression in stroke patients. Earlier studies have excluded people above the age of 60 due to associated poor outcomes; however, newer trials have included this patient subgroup. This review follows a Cochrane Review published in 2012.
To assess the effectiveness of surgical decompression in people with malignant oedema after ischaemic stroke with regard to reduction in mortality and improved functional outcome. We also aimed to examine the adverse effects of surgical decompression in this patient cohort.
We searched the Cochrane Stroke Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL; 2022, Issue 7 of 12), MEDLINE Ovid, Embase Ovid, Web of Science Core Collection, Scopus databases, ClinicalTrials.gov, and the WHO ICTRP to July 2022. We also reviewed the reference lists of relevant articles.
We included randomised controlled trials (RCTs) comparing decompressive craniectomy with medical management to best medical management alone for people with malignant cerebral oedema after MCA ischaemic stroke.
Two review authors independently screened the search results, assessed study eligibility, performed risk of bias assessment, and extracted the data. The primary outcomes were death and death or severe disability (modified Rankin Scale (mRS) > 4) at 6 to 12 months follow-up. Other outcomes included death or moderate disability (mRS > 3), severe disability (mRS = 5), and adverse events. We assessed the certainty of the evidence using the GRADE approach, categorising it as high, moderate, low, or very low.
We included nine RCTs with a total of 513 participants included in the final analysis. Three studies included patients younger than 60 years of age; two trials accepted patients up to 80 years of age; and one trial only included patients 60 years or older. The majority of included trials (six) mandated a time from stroke ictus to treatment of < 48 hours, whilst in two of them this was < 96 hours.
Surgical decompression was associated with a reduction in death (odds ratio (OR) 0.18, 95% confidence interval (CI) 0.12 to 0.27, 9 trials, 513 participants, P < 0.001; high-certainty evidence); death or severe disability (mRS > 4, OR 0.22, 95% CI 0.15 to 0.32, 9 trials, 513 participants, P < 0.001; high-certainty evidence); and death or moderate disability (mRS > 3, OR 0.34, 95% CI 0.22 to 0.52, 9 trials, 513 participants, P < 0.001; moderate-certainty evidence). Subgroup analysis did not reveal any significant effect on treatment outcomes when analysing age (< 60 years versus ≥ 60 years); time from stroke ictus to intervention (< 48 hours versus ≥ 48 hours); or dysphasia. There was a significant subgroup effect of time at follow-up (6 versus 12 months, P = 0.02) on death as well as death or severe disability (mRS > 4); however, the validity of this finding was affected by fewer participant numbers in the six-month follow-up subgroup. There was no consistent reporting of per-participant adverse event rates in any of the included studies, which prevented further analysis.