## 1 Introduction  
Traumatic brain injury (TBI) is defined as an alteration in brain function pathology by a sudden trauma causing damage to the brain. Symptoms can be mild, moderate or severe, depending on the extent of the damage to the brain [1]. The global incidence rate of TBI is estimated to be 69 million cases per annum, of which 5.48 million are estimated to be severe cases [2]. TBI causes a significant burden on individuals and their families, through health loss and disability. TBI has also created a large and growing burden on healthcare systems and nations, due to the complex and expensive medical care that the condition necessitates, and the consequent loss to productivity. The incidence rate of TBI is increasing over time, which is likely due to increases in population density, population ageing and the increasing use of motor vehicles, motorcycles and bicycles [3]. The total annual burden of TBI has been estimated at USD 400 billion [4]  
Global modelling suggests that the incidence of TBI in low to middle income countries (LMICs) is significantly higher than in high income countries (HICs), the main cause of TBI in LMICs being road traffic collisions [3]. By contrast, the CENTER-TBI, a largely HIC-focused registry, collected patient demographics, injury, care pathway and acute care outcome data in 56 acute trauma receiving hospitals across 17 countries in Europe and Israel. The study reported that 56% of the 21,681 patients with TBI acquired their injury through falls, of which the majority, 71%, were ground-level (low-energy) falls [5]. The incidence rate of TBI is increasing. [PERSON] et al. conducted a retrospective cohort study of all patients in Nova Scotia who presented with severe TBI between 2002 and 2018. Over the duration of the study, there were 5590 severe TBI patients, and the rate of severe TBI increased by 39%. The study's results mirrored the findings of the CENTER-TBI registry, that the mechanism of injury amongst patients was predominantly falls (45%). The rate of fall-related TBIs more than doubled between 2002 and 2017 [6]. [PERSON] et al. 's study analysed non-public patient-level data from California's Office of Statewide Health Planning and Development between the years 2005 and 2014. In line with the findings of [PERSON] et al, the study found a 57.7% increase in the number of TBI emergency department visits, which represented a 40.5% increase in TBI related hospital visit rates over the 10-year period [7]. In this context, intracranial pressure (ICP) monitoring has become a standard practice in neurocritical care, for the timely identification of intracranial hypertension, as elevated ICP is associated with poor neuropsychological performance and functional outcomes in TBI patients. ICP is the pressure inside the cranial vault. The Monro-Kellie hypothesis states that under normal conditions the intracranial compartment space, cerebral blood volume and volume inside the cranium are fixed [8]. Changes in ICP are caused by changes in brain volume, cerebral blood volume and the production and/or clearance of cerebrospinal fluid (CSF) [8; 9]. These changes can be caused by a variety of pathological processes, many of which may be caused by TBI, such as localised mass lesions, obstruction to major venous sinuses and cerebral edema or swelling. If any of these changes cause volumetric increases within the cranial vault, compensatory mechanisms occur, in an effort to maintain ICP within the normal ranges, which are generally from 10 to 15 millimetres of mercury (mmHg) for adults and from 3 to 7 mmHg for young children [10]. A critical threshold is reached when space-occupying lesions can no longer expand: without efficacious monitoring and subsequent intervention, this can lead to secondary injury to the brain through neuronal injury, herniation and brain death [11; 12; 13]. ICP monitoring is used either as a guide to treatment or as a diagnostic modality in a number of pathological conditions resulting in neurological injury.