Traumatic brain injury (TBI) is a leading cause of childhood death and disability worldwide. In the United States, childhood head trauma results in 3000 deaths, 50 000 hospitalisations, and 650 000 emergency department (ED) visits annually.^1,2 Children with seemingly minor head trauma, defined here by Glasgow Coma Scale (GCS) scores of 14–15, account for 40–59% of those with TBIs,^3–5 and present a perplexing problem to clinicians. Despite the frequency of childhood minor head trauma, there exists no highly accurate and reliable clinical scoring system for separating those children with minor head trauma at negligible risk of TBI from those at greater risk. Children with TBIs who present with signs of seemingly minor head trauma are at risk for delayed diagnosis and treatment, and such unrecognised TBIs are a source of preventable morbidity.^6–8 Nevertheless, although some TBIs in children with minor head trauma are initially unrecognised and therefore neuroimaging is delayed, a great many more children evaluated for minor head trauma receive unnecessary neuroimaging.

More than 50% of children evaluated in EDs for head trauma in the United States undergo cranial computed tomography (CT) scanning,¹ and this percentage doubled between 1996 and 2000.¹ Children with minor head trauma account for 70–85% of children who receive cranial CT scans during their ED evaluation for head trauma in the United States,^4,5 yet only 4–8% of these CT scans show TBI.^1,4,5,9–12 Furthermore, approximately 5% of those with positive CT scans undergo operative intervention.^4,9 Therefore CT scans are used inefficiently.

Although CT scanning is the reference standard for diagnosing TBI and delayed recognition of TBI increases morbidity, overuse of CT scanning has important drawbacks. These include …