CT scans are very commonly used in the emergency department. In fact, approximately 12% of all emergency department patient visits involve using a CAT scan in a 2012 study. Over 80 million CAT scans are performed annually in the United States. It’s felt that a lot of these are unnecessary. In the past several years we’ve realized that CT scans are associated with the risk of cancer later in life, particularly when they’re performed on children. There’s also some evidence to support that CT scans can decrease patient intelligence and decrease IQ.

CT scans are also expensive and the government is looking at ways to decrease the use of unnecessary CT scans. There are several articles in the December 22, 2015 issue JAMA that look at solutions to decrease the use of unnecessary CAT scans. An article by Easter et al looked at various rules and found that certain findings included signs of a skull fracture, a Glasgow Coma Scale of less than 13, two or more bombing episodes, a decrease in the GCS score and pedestrian struck by motor vehicles. They identify those patients had increased risk of severe inter cranial injuries. They also looked at various clinical decision rules including the New Orleans Criteria, the Canadian [00:02:00] Head Injury Rule.

Easter notes that each year approximately 2.5 million people in the United States present for medical attention after having a head injury. Minor head injury composed approximately 89% of all head injury and is far more common than moderate or severe head trauma.

Clinical Decision Rules to Rule Out Intracranial Injuries

New Orleans Criteria

  • Older than 60 years
  • Intoxication
  • Headache
  • Any vomiting
  • Seizure
  • Amnesia
  • Visible trauma above the clavicle

Canadian CT Head RuleJAMA

  • 65 years or older
  • Dangerous mechanism (pedestrian struck by vehicle, occupant ejected from vehicle, fall >1 m or 5 stairs)
  • Vomiting more than 1 episode
  • Amnesia longer than 30 minutes
  • GCS score less than 15 at 2 hours
  • Suspected open, depressed, or basilar skull fracture

Interpretation of the Rules

  • Patients without any features of the rule are at low risk of severe intracranial injury.

The decision to discharge, observe, or CT the patient with 1 or more features of a rule depends on the setting, clinician’s judgment about the likelihood of injury, patient preference, number of features present, and the particular features present.