Timing of decompressive craniectomy in severe traumatic brain injury: a 2020–2025 review focused on pathophysiological context

Abstract
Traumatic brain injury (TBI) remains a leading cause of death and long-term disability worldwide, and in severe TBI sustained intracranial hypertension is a major driver of secondary injury; decompressive craniectomy (DC) is widely used to control refractory intracranial pressure, yet optimal timing remains controversial, partly because studies often conflate primary DC performed during index evacuation of a focal mass lesion with secondary (rescue) DC performed for refractory intracranial hypertension after maximal medical therapy. This systematic review synthesised contemporary evidence on DC timing/strategy and outcomes while separating adult and paediatric findings and considering surgical intent. After screening 874 records and assessing 139 full texts, seven cohort studies were included (sample size range 89–2,032) from the USA, China, India, Jordan, Germany, and a multinational collaboration; study quality was moderate-to-high (Newcastle–Ottawa Scale 5–6). In adults, early and/or primary DC generally showed lower mortality and modestly higher favourable functional recovery (GOS 4–5), with the largest cohort reporting reduced mortality for early versus late DC (22.4% vs 28.1%; RR 0.80) and higher favourable recovery at 6 months (41.2% vs 36.8%). Primary-versus-secondary comparisons in adult cohorts demonstrated consistent directional trends favouring primary DC, though precision was limited in smaller studies. In paediatric cohorts, findings diverged, with early DC associated with higher mortality in one study and registry analysis identifying timing as prognostic. Early/primary DC was also associated with shorter ICU and hospital length of stay and fewer ventilator days in the largest adult cohort, while overall complication rates were broadly similar but with differing profiles (more haemorrhagic events in early/primary cohorts and more infection/hydrocephalus reporting in late/secondary cohorts). Overall, adult data support early/primary DC when aligned with appropriate indications, whereas paediatric evidence supports physiology-guided individualisation and caution with rigid time thresholds.