Head Injury CT Decision (Canadian CT Head Rule)

Step-by-step decision

Choose step by step as prompted; reaching an endpoint gives the management recommendation. You can go back a step or restart anytime.

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Full pathway

1. [Decision] Applicability
   Does the rule apply? (The Canadian CT Head Rule applies to: GCS 13–15, within 24 h of injury, with loss of consciousness/amnesia/witnessed disorientation. It does not apply (assess directly, CT as needed) to: age <16, anticoagulation/bleeding tendency, post-traumatic seizure, obvious open/depressed fracture, focal neurological deficit, unstable vital signs.)
   • Applies → High-risk/medium-risk factors
   • Does not apply → Excluded group
2. [End] Excluded group
   Excluded groups (e.g. anticoagulation, age <16, focal signs, post-traumatic seizure): do not apply this rule; assess by clinical judgement and the appropriate pathway, most need CT and/or observation and specialist consult.
3. [Decision] High-risk/medium-risk factors
   Any high-risk or medium-risk factor present? (High-risk (suggests need for neurosurgical intervention): GCS <15 at 2 h after injury; suspected open/depressed skull fracture; signs of basilar skull fracture (hemotympanum, raccoon eyes, Battle's sign, CSF oto/rhinorrhea); ≥2 episodes of vomiting; age ≥65. Medium-risk (important brain injury on CT): retrograde amnesia >30 min; dangerous mechanism (pedestrian struck, ejected from vehicle, fall >3 feet or >5 stairs).)
   • Any high/medium-risk present → Head CT needed
   • None → Generally no CT needed
4. [End] Head CT needed
   Any high/medium-risk factor present → obtain a head CT. High-risk suggests possible need for neurosurgical intervention; medium-risk suggests possible CT-positive important brain injury. Individualize with anticoagulation history, etc.
5. [End] Generally no CT needed
   No high/medium-risk factor → generally no head CT needed. Clinical observation, counsel on post-concussion symptoms and return advice (re-attend if worsening).

Source guidelines & references

• Stiell IG, et al. The Canadian CT Head Rule for minor head injury. Lancet 2001

This pathway is our own synthesis of the decision logic in the guidelines above (not the guideline verbatim); thresholds and workflows change as guidelines update — in practice follow the latest guideline, your institution's protocol and the individual patient.

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