Are CT scans being overused in monitoring head injury?

High tech imaging is the gold standard for identifying brain injury. But is it always necessary?

Seems like everywhere you turn, there’s new information about how dangerous head injuries can be. And because they can be so devastating, many doctors are quick to use computed tomography (CT) scans to check for serious injury when they see a young patient who has suffered a blow to the head. (Almost 50 percent of all children taken to U.S. emergency departments for head injury have a CT performed.) But according to a new study co-lead by Lise Nigrovic, MD, MPH, at Children’s Hospital Boston, these CT scans are used far more often than they need to be.

“Only a small percentage of children with blunt head trauma really have something serious going on,” she says. “If a child has suffered a serious injury and is at high risk for head trauma he needs to receive a CT right away. But if the child is at an intermediate risk he can be watched in the ED for a few hours and may not need a CT at all.”

To produce their images, CT scanners use small doses of ionized radiation. The patient’s level of exposure to that radiation is extremely low, but there is data indicating that even small exposure can lead to increased life time risk of cancer. Children may be especially susceptible to this exposure, because their developing tissue is particularly sensitive to the affects of radiation. (Read about the ways Children’s Hospital Boston ensures safety of its patients who receive specialized imaging.)

Based on this information, clinicians are left with a difficult question: How severe must a head trauma be for the benefits of a CT scan to outweigh the risk associated with its use?

Lise Nigrovic, MD, MPH

“Probably less than one percent of the kids who come to emergency departments for head injury have serious enough head trauma to warrant a CT,” Nigrovic says. “But clinicians have the difficult challenge of figuring which patients do fall into that one percent. It’s not quite a needle in the haystack scenario, but it can be difficult.”

Nigrovic’s research, which was just published in the journal Pediatrics, should help make that decision easier for ED doctors. Her findings indicate that if clinicians carefully observe patients at intermediate risk of head trauma for a few hours following injury, they should be able to accurately determine the severity of the injury without the use of a CT. She also found that prolonged observation did not compromise patient safety in any way.

So, if observation is the safer method for judging the extent of intermediate head injuries, why are CT scans used so often? According Nigrovic, many parents—and some doctors—are reluctant to rely on human observation when high-tech equipment is readily available.

“Clearly a significant injury to a person’s head is not something you want to ignore, and CT scanning has always been the gold standard for identifying them,” she says. “Like most technology, if something is readily available, people are going to use it. Often, CT scans fall into that category.”

In addition to monitoring a patient’s symptoms, Nigrovic says the method of injury is usually a good indicator of whether or not a CT is warranted, but that decision should be made on a case-to-case basis.

Doctors should take the method of injury and symptoms into account before ordering CT scans

“The child who is hit by a car or falls from a great height is clearly at more risk for serious head injury than the kid who falls while running on the playground, but that’s not to say every kid in a car accident needs a CT scan and all playground falls don’t,” she says. “What clinicians really need to pay attention to is a combination of how the injury occurred and the symptoms displayed afterward. If it’s deemed that the child is not at high risk for serious injury, then observation is a safer alternative to CT.”

A national effort to reduce CT scanning of patients at intermediate risk of serious head injury requires a little more space and time from ED staff than scanning, but those additional costs may be balanced out by reducing the use of expensive, often unneeded testing. But regardless of the numbers, Nigrovic says the financial gains that could be yielded from her study pale in comparison to the health benefits.

“If you’re extending the time some patients spent in the ED it’s going to have some affect on your workflow in that department,” she says, “On the other hand, CT scans are advanced neuroimaging and have a significant associated cost, so if you do less of them you’re spending less overall on managing head trauma injuries. Either way, the cost aspect is secondary. What’s really important about this study is the data that may be used to reduce unnecessary exposure to ionized radiation in young patients.”

As a quick reference guide, Nigrovic offers the following information if your child suffers 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.