NATURE REVIEWS | NEUROLOGY ADVANCE ONLINE PUBLICATION | 1 Division of Neurosurgery, Department of Clinical Neurosciences, Addenbrooke’s Hospital and University of Cambridge, Cambridge, CB2 0QQ, UK (A. G. Kolias, P. J. Kirkpatrick, P. J. Hutchinson). Correspondence to: A. G. Kolias angeloskolias@ gmail.com Decompressive craniectomy: past, present and future Angelos G. Kolias, Peter J. Kirkpatrick and Peter J. Hutchinson Abstract | Decompressive craniectomy (DC)—a surgical procedure that involves removal of part of the skull to accommodate brain swelling—has been used for many years in the management of patients with brain oedema and/or intracranial hypertension, but its place in contemporary practice remains controversial. Results from a recent trial showed that early (neuroprotective) DC was not superior to medical management in patients with diffuse traumatic brain injury. An ongoing trial is investigating the clinical and cost effectiveness of secondary DC as a last-tier therapy for post-traumatic refractory intracranial hypertension. With regard to ischaemic stroke (malignant middle cerebral artery infarction), a recent Cochrane review concluded that DC improves survival compared with medical management, but that a higher proportion of DC survivors experience moderately severe or severe disability. Although many patients have a good outcome, the issue of DC-related disability raises important ethical issues. As DC and subsequent cranioplasty are associated with a number of complications, indiscriminate use of this surgery is not appropriate. Here, we review the evidence and present considerations regarding surgical technique, ethics and cost-effectiveness of DC. Prospective clinical trials and cohort studies are essential to enable optimization of patient care and outcomes. Kolias, A. G. et al. Nat. Rev. Neurol. advance online publication 11 June 2013; doi:10.1038/nrneurol.2013.106 Introduction Brain oedema can develop after traumatic brain injury (TBI), ischaemic stroke and a number of other condi- tions that affect the brain. 1–6 Owing to the rigid nature of the skull, escalating brain oedema leads to an increase in intracranial pressure (ICP) which, in turn, causes reduc- tion in cerebral perfusion pressure (CPP; mean arterial blood pressure minus ICP), cerebral blood flow (CBF) and oxygenation. These effects contribute to develop- ment of additional brain oedema, 1,7 forming part of a ‘vicious circle’ that, if not interrupted, can lead to brain herniation and death. 2,8 Decompressive craniectomy (DC)—a procedure whereby part of the skull is removed and the under- lying dura is opened—is attractive for management of escalating brain oedema as it can provide additional space for the swollen brain, thereby mitigating the risk of ICP elevation and herniation. Strong evidence exists to suggest that DC can be used to effectively reduce ICP (Figure 1). 9,10 Despite the passing of 100 years since Kocher’s seminal description of DC in 1901, the role of this technique in patient management continues to be debated. The popularity of DC for treatment of patients who experience a TBI or stroke has waxed and waned since the 1950s. 11–15 Since the 1990s, advances in neuro- imaging and in prehospital and neurointensive care have led to a resurgence of interest in the use of DC, which culminated in the publication of results from numerous randomized trials in the 2000s. 16,17–24 Recommendations on the use of DC in patients with TBI and ischaemic stroke have been introduced in clinical guidelines. 25–27 However, the exact indications for DC, optimal timing of treatment and effects of DC on long-term functional outcome remain unclear, and a need to increase our understanding of DC-associated complications and costs has been recognized. 28–32 In this Review, we summarize the available evidence regarding the effectiveness of DC following TBI, ischae- mic stroke and other neurological conditions. We also consider surgical technique, ethics and cost-effectiveness of DC, and suggest directions for future studies. Historical aspects The practice of removing part of the skull dates back to the beginning of the Neolithic period, around 10,000 BC. 33 The terms ‘trepanation’ or ‘trephina- tion’ are etymologically derived from the ancient Greek word trypanon: tool used for drilling holes. Archaeological evidence of the practice of trephina- tion has been found in Europe, North America, Central America, South America, Africa and Asia. 33 Hippocrates (c.460 BC–c.370 BC) was the first to systematically describe skull fractures and discuss which types of injury should be treated with trephination. 34 Furthermore, he Competing interests A. G. Kolias declares an association with the British Neurosurgical Trainee Research Collaborative (which has received funding from Codman). P. J. Hutchinson declares an association with the following company: Technicam Ltd. See the article online for full details of the relationships. P. J. Kirkpatrick declares no competing interests. REVIEWS © 2013 Macmillan Publishers Limited. All rights reserved