Interpretation
| Result | Meaning |
|---|---|
| Any high-risk factor | CT: 100% sensitive for need for neurosurgical intervention (derivation) |
| Any medium-risk factor | CT: 98.4% sensitive for clinically important brain injury (derivation) |
| None | CT not required by the rule |
Formula
High risk: GCS <15 at 2 h · suspected open/depressed skull fracture · sign of basal skull fracture · vomiting ≥2 · age ≥65. Medium risk: amnesia before impact ≥30 min · dangerous mechanism. Any factor → CT.
Clinical pearls
- Inclusion: patients ≥16 y with blunt head trauma causing witnessed LOC, definite amnesia or witnessed disorientation, GCS 13–15, seen within 24 h of injury.
- Not applicable (excluded from derivation): age <16, anticoagulant use or bleeding disorder, seizure after injury, obvious open skull injury, focal neurological deficit, unstable vital signs, pregnancy, no clear history of trauma, or returning for reassessment.
- Derivation sensitivity: 100% for neurosurgical intervention and 98.4% for clinically important brain injury (Stiell 2001).
Examples
canadian ct head 45 yo fell down 6 stairs, brief loc, gcs 15, no vomitingdoes a 70 year old with minor head injury, GCS 15, LOC, need a CT head
FAQ
Does the Canadian CT Head Rule apply to patients on anticoagulants?
No. Anticoagulated patients and those with bleeding disorders were excluded; most guidelines advise a low threshold for CT in them.
Does the rule apply without loss of consciousness?
It was derived only in patients with witnessed LOC, definite amnesia or witnessed disorientation.