The recommendations on referral for people with head injury are based on the clinical guidance Head injury: triage, assessment, investigation and early management of head injury in infants, children and adults, produced by the National Collaborating Centre for Acute Care, and commissioned by the National Institute for Health and Clinical Excellence (NICE) [National Collaborating Centre for Acute Care, 2007]. It can be downloaded from www.nice.org.uk (pdf).

Recognition of high risk factors for brain injury following head injury

• The risk of intracranial complications is higher in people with a diagnosis of skull fracture. It is estimated, from a meta-analysis of the value of the radiological diagnosis of skull fracture, that the risk of developing an intracranial haematoma is about 12-times higher with a radiographically-detected skull fracture than without this diagnosis [Hofman et al, 2000].
• Post-traumatic neurological signs, such as focal neurological deficits or seizure, are highly associated with the risk of an intracranial complication [Teasdale et al, 1979].
• Vomiting is consistently identified as a high risk factor for brain injury. However the predictive power in infants and children is controversial, as 16% of infants and children less than 12 years of age vomit after minor head injury, and this is not related to features specific to the head injury [Brown et al, 2000].
• High-energy injury has been identified as a high risk factor for clinically important brain injury [Stiell et al, 2001].
• Altered consciousness after a head injury increases the risk of intracranial complications, although the absolute risk remains low [Teasdale et al, 1990].
• Amnesia after head injury increases the risk of intracranial complications, although the length and type of amnesia are controversial [Teasdale et al, 1990].
• Drug and alcohol intoxication have been identified as independent risk factors following head injury. They can also hinder making a correct diagnosis as they may mask symptoms [Cook et al, 1994].
• Headache is controversial in that there is clear evidence both for and against it being a good indicator for brain injury following head injury. This may in part be due to the difficulties that arise when defining headache, particularly in infants and children.
• There is limited evidence to indicate that bleeding disorders and anticoagulant use contribute to an increased risk of brain injury following head injury.
• Increasing age is associated with an increased risk of intercranial complications and a poorer prognosis, following head injury [National Collaborating Centre for Acute Care, 2007]. The NICE guideline development group adopted a standard age threshold of 65 years and older.
• NICE identified a cohort study which developed a model to predict clinically important brain injury [Stiell et al, 2001]. This model suggested that people who were over 65 years of age had a 4 fold increased risk (odds ratio 4.1, 95% CI 2.8 to 6.1) of developing clinically important brain injury (resulting from a head injury) if loss of consciousness or amnesia were present.