A child with head trauma who briefly lost consciousness but has no other signs or symptoms related to the head trauma is unlikely to have sustained a serious brain injury. In these cases, CT scans of the head are not routinely required, according to a study published online July 7 in JAMA Pediatrics.

Since the radiation involved in a CT scan has a small but non-negligible long-term risk of cancer, of particular concern among children, pediatric patients presenting to the emergency department with isolated loss of consciousness should avoid undergoing a likely unnecessary CT scan.

“Given that a history of [loss of consciousness] has a very strong influence on imaging decisions these findings highlight the need for clinicians to determine whether [loss of consciousness] occurred with or without other [clinically important traumatic brain injury] risk factors when deciding on CT use,” wrote Nathan Kuppermann, MD, MPH, of the University of California, Davis School of Medicine, and colleagues from the Pediatric Emergency Care Applied Research Network (PECARN).

Kuppermann and colleagues had previously explored justification for CT scans in children with suspected brain injury, and published a paper in The Lancet in 2009 detailing the PECARN traumatic brain injury prediction rules. These rules included factors such as loss of consciousness, scalp hematoma, abnormal mental state and palpable skull fracture, among others, as a way of determining risk for clinically significant brain injuries.

The current study aimed to determine whether loss of consciousness alone was enough to warrant a CT scan. In a planned secondary analysis of the original multicenter cohort study used to establish the PECARN rules, Kuppermann and colleagues looked at more than 40,000 children 18 years or younger with blunt head trauma from 2004-2006.

Results showed 15.4 percent of the children lost consciousness, and the prevalence of a clinically important TBI with any history of loss of consciousness was 2.5 percent. However, the rate of clinically important TBI in those with a loss of consciousness and no other PECARN predictors was 0.5 percent. If the child had isolated loss of consciousness and had no other signs of head trauma whatsoever, including factors outside of the PECARN prediction rules, the incidence of important brain injury fell to 0.2 percent.

“Because [clinically important TBI] is very uncommon in children with isolated [loss of consciousness], routine CT scanning is unlikely to be beneficial, and a period of observation prior to CT decision making may safely decrease CT use,” wrote the authors.