Traumatic brain injury (TBI) is defined as a sudden insult that disrupts the normal equilibrium of brain components and pressure within the skull [2]. TBI has an estimated incidence of 1.5 million annual cases in the United States and is a leading cause of mortality and disability globally [13], [23]. Furthermore, TBI accounts for nearly one-third of all trauma-related deaths [9]. One of the most critical complications associated with TBI is increased intracranial pressure (ICP), which poses life-threatening outcomes due to a loss of balance between the production and absorption of cerebrospinal fluid (CSF), causing devastating consequences ranging from cerebral herniation and irreversible brain damage to eventual death [5]. As such, prompt recognition and management of elevated ICP is crucial to mitigating the risk of secondary brain injury and optimizing survival and neurological recovery.

Elevated ICP can develop in up to 85 % of patients following severe TBI and is a neurosurgical emergency that warrants immediate intervention [19]. The Monro-Kellie doctrine states that the sum of volumes of blood, brain, and CSF remain constant within an enclosed skull, and an increase in one necessitates a decrease in the others [16]. As such, when left untreated, elevated ICP can cause brain herniation with subsequent irreversible brain injury and death. The initial management of these patients includes noninvasive interventions such as head elevation, hyperosmolar therapy (e.g. mannitol, hypertonic saline), sedatives, paralytics, hypothermia, and hyperventilation [21], [24], [28]. When these measures are unlikely to be adequate or prove to be ineffective, however, surgical options are pursued [24]. While intraparenchymal pressure monitoring and decompressive craniectomy (DC) can be used, external ventricular drain (EVD) placement remains the gold standard surgical option in the acute setting as it allows for both pressure monitoring and CSF drainage as needed and can be expeditiously placed at the bedside rather than in an operating room [6], [10], [30].

Given the poor outcomes and complications many patients experience following EVD placement, there remains a need to determine the optimal timing of EVD placement to guide clinical decision-making and improve prognosis in managing elevated ICP [8], [27]. As such, this paper aims to compare the differences in in-hospital mortality following early and late EVD placement in patients with TBI using a retrospective analysis of over 6000 patients from a nationwide trauma registry. To our knowledge, this represents the largest analysis to date to evaluate in-hospital outcomes based on EVD placement timing in patients with TBI.