Clinical decision rules for head CT in trauma


Clinical decision rules to guide providers when determining which patients require urgent CT neuroimaging.

Decision Rule Performance

Canadian Head CT Rule[1] New Orleans NEXUS II ACEP Clinical Policy
Sensitivity 99% 99% 97% Unknown
Specificity 47% 33% 47% Unknown

Canadian CT Head Rule[2]

Inclusion Criteria

  • Blunt head trauma causing loss of consciousness, amnesia, or disorientation
  • GCS 13-15
  • Age ≥ 16yr
  • No coagulopathy nor on anti-coagulation
  • No seizure


Head CT not required if NONE of the following are present

  • Age ≥ 65 years
  • Vomiting > 2 episodes
  • Suspected open or depressed Skull Fracture
  • Signs suggesting basal skull fracture:
    • Hemotympanum
    • Racoon eyes
    • CSF otorrhea or rhinorrhea
    • Battle's sign (bruising around mastoid process)
  • GCS < 15 at 2 hours post injury
  • Retrograde Amnesia > 30min
  • Dangerous mechanism
    • Pedestrian struck by vehicle
    • Ejection from motor vehicle
    • Fall from elevation >3 feet or 5 stairs

New Orleans Rule

Inclusion Criteria

  • Age >18
  • GCS 15
  • Blunt head trauma occurring within previous 24hr causing LOC, amnesia, or disorientation


Head CT not required if NONE of the following are present

Nexus II Rule


Head CT not required if NONE of the following are present

ACEP Clinical Policy (2008)

  • Inclusion:
    • Non-penetrating trauma to the head
    • Presentation to ED within 24 hours of injury
    • GCS 14 or 15 on initial evaluation in ED
    • Age ≥ 16
  • Exclusion:
    • Penetrating trauma
    • Patients with multi-system trauma
    • GCS < 14 on initial evaluation in the ED
    • Age < 16
  • Level A:
    • A noncontrast head CT indicate in head trauma patients with LOC or post-traumatic amnesia only if ≥ 1 of following is present:
      • Headache
      • Vomiting
      • Age> 60
      • Drug or alcohol intoxication
      • Deficits in short-term memory
      • Physical evidence of trauma above the clavicle
      • Post-traumatic seizure
      • GCS < 15
      • Focal neurological deficit
      • Coagulopathy
  • Level B:
    • A noncontrast head CT should be considered in head trauma patients with no LOC or post-traumatic amnesia if there is:
      • Focal neurological deficit
      • Vomiting
      • Severe headache
      • Age ≥ 65
      • Physical signs of basilar skull fracture
      • GCS < 15
      • Coagulopathy
      • Dangerous mechanism of injury
    • Patients with an isolated TBI who have a negative head CT scan result are at a minimal risk for developing an intracranial lesion and therefore may be safely discharged from the ED.
  • Level C:
    • In mild TBI patient with significant extracranial injuries and a serum S-100B level ≤ 0.5ℳg/L measured w/in 4 hours if injury, consideration can be given to not performing a CT.
    • Mild TBI patients discharged from the E should be informed abut post-concussive symptoms.
  • No specific recommendation for use of head MRI in patient with mild TBI


See Also


  • Clinical policy: neuroimaging and decisionmaking in adult mild traumatic brain injury in the acute setting; Ann Emerg Med, 2008
  • Annals of Emerg Med 2009; 53, 2:180-188.
  • Haydel MJ, Preston CA, Mills TJ, Luber S, Blaudeau E, DeBlieux PM. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000;343:100–5.
  • Papa L et al. Performance of the Canadian CT Head Rule and the New Orleans Criteria for predicting any traumatic intracranial injury on computed tomography in a United States level I trauma center. Acad Emerg Med 2012 Jan; 19:2


Ross Donaldson