EBQ:Canadian Head CT Rule

Complete Journal Club Article
Stiell IG, et al. "The Canadian CT Head Rule for patients with minor head trauma". The Lancet. 2001. 357(9266):1391-96.
PubMed Full text PDF

Clinical Question

Can a decision rule be used to determine which patients require CT imaging after head trauma?


The Canadian CT head rule is a effective method for determining the need for a patient to receive a non contrast brain CT after head trauma.

Major Points

The trial found that the following criteria had 100% sensitivity for identifying patient at risk for neurologic intervention with minor head injury

  1. GCS score <15 at 2h post injury
  2. Suspected open or depressed skull fracture
  3. Any sign of basal skull fracture (hemotympanum, ‘racoon’ eyes, cerebrospinal fluid otorrhoea/rhinorrhoea, Battle’s sign)
  4. Vomiting ≥ 2episodes
  5. Age ≥ 65 years
  • Minor head injury is defined as witnessed loss of consciousness, definite amnesia, or witnessed disorientation in a patients with a GCS score of 13–15

The moderate risk group (for brain injury on CT) was identified with 95% sensitivity if any of the following were present:

  1. Amnesia before impact >30 min
  2. Dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height >3 feet or five stairs)


  • Prospective cohort study in 10 Canadian community and teaching institutions
  • N=3121


Inclusion Criteria

  • Blunt Trauma to the head causing witnessed loss of consciousness, definite amnesia, or witnessed disorientation)
  • GCS ≥ 13 on ED arrival
  • Head injury within the last 24 hours

Exclusion Criteria

  • Less than 16 years old
  • Minimal head injury (no loss of consciousness, amnesia, or disorientation)
  • No clear history of trauma as the primary event (eg, primary seizure or syncope)
  • Obvious penetrating skull injury or obvious depressed fracture
  • Acute focal neurological deficit
  • Unstable vital signs associated with major trauma
  • Seizure before assessment in the ED
  • Bleeding disorder
  • Using oral anticoagulants
  • Returned for reassessment of the same head injury
  • Pregnant

Baseline Characteristics

  • Mean age: 38 years
  • Age range 16-99
  • Men: 69%
  • Mean time between injury and physician assessment: 3.1 hours
  • Arrival by ambulance: 73%
  • Transfer from outside hospital: 13%
  • Witnessed loss of consciousness: 46%
  • Amnesia: 87%
  • Initial GCS score:
    • 15: 80%
    • 14: 17%
    • 13: 4%
  • Mechanism of injury:
    • Fall: 31%
    • MVA: 26%
    • Assault: 11%
    • Sports: 10%
    • Bicycle: 7%


  • Patients underwent standard CT of the head according to the judgment of the treating physician.
  • The reliability of the radiography interpretations was assessed by having abnormal CT scans, and 5% (randomly selected) of normal scans reviewed by a second radiologist who was unaware of the first interpretation.
  • Patients were classified as having no clinically important brain injury if af 14 days they had:
    • no complaints of memory or concentration problems
    • no seizures
    • NO focal motor findings
    • Score ≤ 10 on the Katzman Short Orientation-Memory-COncentration Test
    • Returned to normal daily activities


High risk by decision rule, requiring neurological intervention: Sensitivity 100% (95% CI 92-1000) Specificity 68.7% (95% CI 67-70%)

With 2 moderate risk criteria added in (consisting of 7 criteria): Sensitivity 98.4% (95% CI 96%-99%) Specificity 49.6% (95% CI 48-51%)



Funded by peer-reviewed grants from the Medical Research Council of Canada (MT-13699) and the Ontario Ministry of Health Emergency Health Services Committee (11896N)

See Also


1 Besides the Canadian Head CT Rule, which other clinical decision rules in adults are available to emergency physicians? (more than one answer possible)

New Orleans Criteria (NOC)
Ottawa Head CT Rule
San Francisco CT Head Rule

2 All are criteria for the Canadian Head CT Rule EXCEPT? (more than one answer possible)

Age <15
Basilar skull fx signs
Auto vs. Peds