Overall, roughly half of US children taken to hospital Emergency Departments (EDs) for a head injury receive a head CT scan, often to ease worried parents' concerns. Yet true traumatic brain injury is uncommon. A multi-centre study of more than 40,000 children with minor blunt head trauma, led by Children's Hospital Boston and UC Davis, shows that allowing a period of observation can reduce the use of head CT by as much as half without compromising care – and without exposing children to ionizing radiation. Results appear in the June 2011 issue of Paediatrics.

“Only a small percentage of children with blunt head trauma really have something serious going on,” says Lise Nigrovic, MD, MPH, of Children's Hospital Boston, who co-led the study with Nathan Kuppermann, MD, MPH, chair of the Department of Emergency Medicine at UC Davis. “If you can be watched in the ED for a few hours, you may not need a CT.”

This change in practice would not only be cost-saving, but is better medicine, the researchers say.

Nigrovic, Kuppermann and colleagues analysed the outcomes of children presenting at 25 different emergency departments, as part of a large prospective study conducted by the Paediatric Emergency Care Applied Research Network (PECARN). Of 40,113 children whose records could be analysed, 5,433 (14 percent) were observed before making a decision about CT use. Observation times varied, as did the severity of head trauma.

Overall, the children who were observed had a lower rate of CT than those not observed (31 vs. 35 percent). When the researchers matched the observed and non-observed groups for severity of head injury and the practice style of different hospitals, this difference was more pronounced: The likelihood of a CT scan in the observed group was about half that of similar non-observed patients (odds ratio, 0.53). In particular, children whose symptoms improved during observation were less likely to eventually have a CT.

Allowing for an observation period did not compromise safety, the study found: Clinically important traumatic brain injury -- resulting in death, neurosurgical intervention, intubation for more than 24 hours or hospital admission for two nights or more -- was equally uncommon in the observed and non-observed groups (0.75 vs. 0.87 percent).

Nigrovic and Kuppermann note that cranial CT itself presents additional risks for children. Children's growing brain tissue is more sensitive to ionizing radiation than adults', and because of their longer life expectancy, their lifetime risk of developing a radiation-induced malignancy is greater.

“CT isn't bad if you really need, but you don't want to use it in children who are at low risk for having a significant injury,” says Nigrovic. “For parents, this means spending a couple of extra hours in the ED in exchange for not getting a CT. It's the children in the middle risk groups – those who don't appear totally normal, but whose injury isn't obviously severe -- for whom observation can really help.”

The researchers were unable to determine the actual length of time the children were observed in the ED, a question they would like to investigate in the future. Practice guidelines from the American Academy of Paediatrics recommend a child be carefully observed for 4 to 6 hours after injury.

“There is a clear need to develop appropriate and safe guidelines for decreasing the number of inappropriate head CT scans that we do on children,” says Kuppermann. “The results of this analysis demonstrate that a period of observation before deciding to use head CT scans on many injured children can spare children from inappropriate radiation when it is not called for, while not increasing the risk of missing important brain injuries.”

Nigrovic offers the following general guidelines for parents whose child has a head injury: check with your primary care clinician before taking the child to the ED. If your child has headache, vomiting and/or confusion, or symptoms that worsen over time, an ED visit is appropriate. The ED clinician may reasonably choose to observe your child for several hours once you arrive before deciding about a head CT. The change of symptoms over time is an important factor in deciding whether to obtain a cranial CT.

The study was funded by the Health Resources and Services Administration/Maternal and Child Health Bureau, Division of Research, Training, and Education, and the Emergency Medical Services of Children Programme.

Children's Hospital Boston is home to the world's largest research enterprise based at a paediatric medical centre, where its discoveries have benefited both children and adults since 1869. More than 1,100 scientists, including nine members of the National Academy of Sciences, 12 members of the Institute of Medicine and 13 members of the Howard Hughes Medical Institute comprise Children's research community. Founded as a 20-bed hospital for children, Children's Hospital Boston today is a 395 bed comprehensive centre for paediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Children's also is the primary paediatric teaching affiliate of Harvard Medical School.