Head injury or traumatic brain injury is a ubiquitous phenomenon in all societies and affects up to 2 per cent of the population per year (Bullock et al. 2006). Although the causes of head injury and its distribution within populations vary, it can have devastating consequences both for the patient and family (Tagliaferri et al. 2006). In some countries severe traumatic brain injury is the commonest cause of death in people under 40 years (Lee et al. 2006), and it is estimated that the sequelae of head injury cost societies billions of dollars per year. Understanding of the pathophysiology, diagnosis, and management have all improved dramatically in the last few decades (Steudel et al. 2005). However within western society, perhaps one of the greatest benefits has been the reduction in severe craniocerebral injuries following motor vehicle accidents. This has arisen because of increased safety in car design, seat-belt legislation, the introduction of air-bags, enforcement of speed limits, and the societal conformity to drink-driving legislation. For instance, because of these changes, in the last 15 years the number of severe head injuries managed in the Clinical Neuroscience unit in Edinburgh has decreased by around 66 per cent. Unfortunately in some developing countries one legacy of increased traffic, particularly of motor cycles, is an epidemic of head injuries amongst young adults (Lee et al. 2006). With the number of severe head injuries declining in many countries the challenge will be to provide better care for patients with minor head injury, about 10 times more common than severe injury (Steudel et al. 2005).
Ageing patients who tend to fall over, falls associated with increased alcohol consumption, and domestic or social assaults probably now contribute to the majority of head injuries (Flanagan et al. 2005; Steudel et al. 2005; Tagliaferri et al. 2006). Sporting injuries are fortunately uncommon as a cause of severe craniocerebral injury, although horse riding accidents can sometimes be devastating particularly in teenage girls. In some countries injuries from hand guns and other missiles are common (Aryan et al. 2005), but in European countries many such injuries are self-inflicted. Prompt management of intracranial haematoma, which occurs in 25–45 per cent of severe head injuries, 3–12 per cent of moderate injuries, and 0.2 per cent of minor injuries, and the rehabilitation of patients with head injury are now important areas in clinical neuroscience (Flanagan et al. 2005; Bullock et al. 2006b, c).