A team of researchers from pediatric institutions across Canada has developed a set of rules to help doctors decide whether a child with a minor head injury should receive a CT scan.

The seven clinical signs — dubbed the CATCH rules — were derived from a study of almost 3,900 children aged 16 and under, who were examined at 10 Canadian pediatric teaching hospitals after suffering a minor head trauma.

There are currently no widely accepted, evidence-based guidelines on the use of CT scans in children with minor head injuries caused by falls and other accidents, said lead author Dr. Martin Osmond, an emergency room physician at the Children's Hospital of Eastern Ontario.

The CATCH (Canadian assessment of tomography for childhood injury) rules are intended to help standardize the use of CT scans and eliminate those that are unnecessary, he said.

Each year, more than 650,000 children with minor head injuries arrive at hospital emergency departments across North America, reporting a loss of consciousness, amnesia, disorientation and/or vomiting.

CT scans are important for diagnosing serious brain injuries, but they expose children to the potentially harmful effects of ionizing radiation and significantly add to health-care costs, the authors say.

"There is growing concern that early exposure to ionizing radiation may result in a significant rise in lifetime fatal cancer risk," Osmond explained. "CT scans give a lot of radiation [300 to 600 times a typical X-ray], but they also give a lot of important information."

"So when the child needs a scan, it's the best test to look for bleeding inside the head."

In Canada, use of CT scans to investigate minor head injuries in Canadian pediatric emergency departments soared to 53 per cent in 2005 from 15 per cent in 1995.

"So there was a three-fold increase over a decade," Osmond said Monday from Ottawa. But among children who received CT scans, less than one per cent needed neurosurgery because of a serious brain injury and just four per cent were found on CT scan to have any kind of bleeding inside the skull that required intervention.

"So the vast majority of CT scans are negative," Osmond said.

Rule guides doctors

The signs of head trauma requiring a CT scan include an open or depressed skull fracture, a headache that worsens over time and a dangerous cause of injury — for instance, a motor vehicle crash or falling off a bicycle while not wearing a helmet.

Any one of the CATCH signs would tell a doctor that a CT scan should be done, he said.

"But if they're all negative, we think the child can be safely sent home — with observation — and would not urgently or immediately need a CT scan."

Osmond said the team of researchers, whose paper is published in this week's issue of the Canadian Medical Association Journal, is following up with a validation study that involves 5,000 children with minor head trauma.

Once the CATCH rules are validated, "we would want to implement [them] in emergency departments throughout Canada," he said.

"Physicians want to do the best for their patients. In all cases it requires getting the evidence around which patients require tests and which ones can safely not have a test."