Mayo Clinic revises pediatric CT practice management guidelines

The number of CT scans performed on children younger than 14 tripled between 1996 and 2005, then slowly began to decline amid growing concerns about the long-term effects of ionizing radiation on the increasing population of young patients.

Children are more radiosensitive than adults are, and their longer life expectancy provides more opportunity for radiation-associated problems to develop. They are also more likely to experience cumulative radiation damage because the dose of additional radiation from each future X-ray study adds up.

A 2012 British study published in The Lancet found that the amount of radiation absorbed from two or three head CTs might triple the risk of brain tumors and the same dose applied to bone marrow could triple the risk of leukemia, the most common cancer in children and teens.

The challenge in emergency medicine is to balance the lifetime risk of cancer in scanned children — an estimated 5,000 cancers a year — against the detection of significant brain injury. In 2011, the Mayo Clinic Trauma Center in Rochester, Minn., a Level I adult and pediatric trauma center that is verified by the American College of Surgeons and designated by the commissioner of the Minnesota Department of Health, implemented practice management guidelines (PMGs) to help guide such decisions.

The guidelines advise against scanning children who have no signs or symptoms of brain injury and recommend either observation or imaging for those who have only one of several risk factors, such as severe headache or a history of vomiting or loss of consciousness.

In moderate-risk cases, the choice between observation and imaging depends on a number of clinical and social factors, including physician comfort level, worsening symptoms since presentation and parental preference.

PMG outcomes

After implementation of the guidelines, researchers studied head imaging rates at Mayo Clinic, using 2010 statistics as a control. Although all the data aren't yet available, James L. Homme, M.D., assistant professor of emergency medicine and pediatrics at Mayo Clinic in Minnesota, says the results to date are surprising.

"We saw no decrease in pediatric imaging between 2010 and 2011," he says. "We were pleased to see that imaging rates at Mayo Clinic in Rochester are much lower than the national average, but they aren't as low as we'd like them to be. There is definitely more that can be done."

To that end, Dr. Homme and colleagues are revising the 2011 PMGs to reflect another study finding: No intermediate-risk children had a clinically significant brain injury on CT. He explains, "The original guidelines recommend observation or scanning in kids with a single factor. The revised version will recommend against CT imaging for those children."

For patients with two risk factors, a period of observation in the ED or at home will be recommended, depending on symptoms and time of injury. "If the injury took place eight hours ago, accompanied by vomiting and headache which have now improved, the child may just need active observation at home, not in the ED," Dr. Homme says. "That will all be spelled out in the new guidelines."

Only 4 percent of children at highest risk were found to have a clinically significant injury, and Dr. Homme says that category will likely be modified, too, although high-risk variables, such as a low Glasgow Coma Scale (GCS) score and signs of basilar skull fracture, are not equally weighted.

Clinical decision aid

Studying the care of injured children and modifying treatment based on data and outcomes is one of the hallmarks of the Mayo Clinic Trauma Centers.  To help providers and parents make educated choices about scanning versus observation in intermediate-risk children, Mayo has  developed a clinical decision aid that is currently being studied in a multicenter clinical trial.

"We want to help parents and providers to understand a child's true risk," Dr. Homme notes. "A child's overall risk for a clinically important traumatic brain injury is very low. But if the child is getting on a plane the next day to fly to a remote area where there is little access to medical care, imaging might make sense. That's an unlikely scenario, but it's one of the variables that make decision-making tricky. The right choice for most kids in the intermediate category is observation, but there is always potentially some other variable that comes into play."

For more information

Pearce M, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: A retrospective cohort study. The Lancet. 2012;380:499.