Head CT (Canadian Rule)

Canadian CT Head Rule

Not applicable for non-trauma, GCS<13, Age <16, Bleeding disorder or on anti-coagulation (e.g. Coumaidn, Debigatran), Obvious open skull fracture.

If ANY High Risk factor present – then get a CT Head

1. Age >65 years
2. Suspected Open or Depressed skull fracture
3. Signs suggesting Basal skull fracture
   1. Hemotympanum
   2. Racoon eyes
   3. CSF otorrhea or rhinorrhea
   4. Battle sign
4. Vomiting > 2 times
5. GCS <15 at 2 hours post injury

If ANY Medium Risk factor present – then get a CT Head

1. Amnesia before impact >30min
2. Dangerous mechanism
   1. Pedestrian struck by vehicle
   2. Ejection from motor vehicle
   3. Fall from elevation >3 feet or 5 stairs

Canadian rule vs. New Orleans vs. Nexus II rules

Comparison done to evaluate Sensitivity and Specificity for clinically important intracranial injuries

Sensitivity

Canadian 99% vs New Orleans 99% vs. Nexus II 97%

Specificity

Canadian 47% vs. New Orleans 33% vs. Nexus II 47%

Source

1. Ann of Emerg Med 2009; 53, 2:180-188.
2. http://www.ohri.ca/emerg/cdr/cthead.html