May 9, 2011 -- A period of observation in the emergency department after a minor childhood head injury can reduce the use of a CT scan by as much as half without affecting good care, according to a new study.
As a result, the child may be exposed to less radiation. That reduces the long-term risks, such as the link with accumulated radiation exposure and cancers.
"We document that observation after minor blunt head trauma reduces CT scan use without missing important injuries," says researcher Lise Nigrovic, MD, MPH, attending physician in emergency medicine at Children's Hospital Boston and assistant professor of pediatrics at Harvard Medical School.
With other researchers from the federally funded Pediatric Emergency Care Applied Research Network, Nigrovic evaluated more than 40,000 children. All were under age 18 and had minor blunt head trauma. They had been brought to one of 25 emergency departments between June 2004 and September 2006.
The study is published in Pediatrics.
Observation vs. CT Scan
Of the 42,412 children enrolled in the study, the researchers analyzed 40,113.
The minor head trauma occurred in a variety of ways, Nigrovic tells WebMD. "In the youngest, the most common is a fall, such as rolling off the bed, or running at high speed into another object."
For older children, the head injuries were often the result of sports activity or car accidents.
Of the 40,113 children, 5433 (14%) of the children were observed before making a decision on CT.
The CT use was lower in those who were observed than in those not -- 31.1% compared to 35%.
However, the rate of clinically important traumatic brain injury found in both groups was similar.
The researchers did not determine the actual observation time. However, guidelines from the American Academy of Pediatrics recommend a child be observed carefully for four to six hours after such injuries.
The researchers matched the observed and non-observed for severity of injury and the practice patterns of various hospitals. They found the likelihood of a CT scan in the observed group was about half that of the similar non-observed patients.
Of the 5433 children in the observation group, 3,744 (69%) were sent home without a scan. Of those, 26, (0.7%) returned later to have one. And of those, four children had traumatic findings on the scan, but only one had a clinically important injury. That child was hospitalized for two nights.
Of the 34,680 children in the non-observed group, 22,532 (65%), were sent home without a CT scan. Of those, 81 (0.4%) returned for a CT scan. And of these, three had traumatic findings but none had a clinical important injury.
Of a head CT scan, Nigrovic says: "It's an incredibly valuable tool when used on the appropriate patient."
However, experts must weigh the long-term risks of the radiation.
The estimates of how great this risk is differ. However, experts know children are at greater risk than adults. Their tissues are more radiosensitive. And they have a longer life expectancy and so a longer time during which radiation-induced cancer could develop.
When a head injury is clearly severe, a child will get a CT scan without the observation period, of course, says Donald Frush, MD, chair of the American College of Radiology Pediatric Imaging Commission. He reviewed the findings for WebMD but was not involved in the study.
But for minor head trauma, he says, "observation is a reasonable strategy." Frush is also chair of pediatric radiology at Duke University Medical Center in Durham, N.C.
The study, he says, supports the concept of observation in these cases.
If a CT scan is deemed necessary, he says, parents should know that the dose provided by a single CT scan to the brain of a child is roughly equal to six months to a year of ''background radiation."
He defines that as ''radiation we get from naturally occurring radioactive substances in the soil, and cosmic radiation -- from the heavens."
The radiation from a head CT, he says, ''can be as low as a few dozen chest X-rays to just over 100 chest X-rays. One chest X-ray is worth just a few days of background radiation.''
Deciding whether to do a CT scan in a child -- and when -- is complicated, Frush says.
Some parents are very concerned about waiting during the observation period, he says. Others are concerned about the radiation exposure.
"I would say that a single CT scan of the brain should provide a very low dose that should not be of concern to parents in terms of risk," Frush tells WebMD.
Parents should ask the following questions if a CT scan is needed, he says.
- Is an exam necessary at this time? Why?
- If it is done, will the CT be done with my child's size and age taken into account?
- Will the person doing it have experience in children's scans?