Canadian CT Head Rule
Rule out clinically important brain injury in adults with minor head trauma (GCS 13–15). Reduces unnecessary CT scans.
Inclusion Criteria
Patient must be ≥ 16 years old, have blunt head trauma resulting in witnessed LOC, amnesia, or confusion, and GCS 13–15.
Exclusions: Anticoagulants, bleeding disorder, open skull fracture, age < 16.
High Risk Factors (Require CT)
Medium Risk Factors (Consider CT)
Disclaimer: For educational purposes only. Not a substitute for clinical judgment.
About This Tool
What Is the Canadian CT Head Rule?
The Canadian CT Head Rule (CCHR) is a highly validated clinical decision rule developed to identify patients with minor head injury who do NOT need a CT scan. It aims to reduce unnecessary radiation exposure and resource use while missing zero neurosurgical cases.
Validation
In the original study (Stiell et al., Lancet 2001), the rule was 100% sensitive for predicting need for neurosurgical intervention and clinically important brain injury. It is widely considered superior to the New Orleans Criteria for specificity (reducing scans).
🔑 Clinical Pearls
- "Clinically important brain injury" is defined as any acute finding on CT that would require admission or neurosurgical follow-up.
- Dangerous mechanism includes: pedestrian struck by vehicle, occupant ejected from vehicle, fall from > 3 feet (or > 5 stairs).
- Retrograde amnesia refers to forgetting events BEFORE the injury (anterograde is after).
- Elderly patients (≥ 65) automatically qualify for a scan under this rule due to higher risk of subdural hematoma.
Formula last verified: February 2026