Canadian CT Head Injury/Trauma Rule

Head trauma complaints in the outpatient setting (emergency department, urgent care and primary care) are common. However, the majority of patients have minor head trauma that will not require specialized treatment or neurosurgical intervention. Yet, rates of CT imaging of the head have more than doubled starting in the early 1990s. The Canadian CT Head Rule (CCHR) is a well-validated clinical decision aid that assists clinicians in determining which minor head injury patients need head CT imaging. Thus, safely ruling out the presence of intracranial injuries that would require neurosurgical intervention or admission. In the validation trial (Stiell, 2005), the CCHR was 100% sensitive for both clinically important brain injuries and injuries that require neurosurgical intervention. Specificity was 76.3% for clinically important brain injuries and 50.6% for injuries that required neurosurgical intervention. It is 70% sensitive for clinically important brain injury in patients with alcohol intoxication (Easter, 2013). In most studies 7-10% of patients had positive CT's considered to be clinically important brain injuries, but < 2% required neurosurgical intervention. The rule excludes patients on blood thinners, > 16 years old and with seizure after injury.

Providers often consider applying the Canadian CT Head Rule (CCHR) for head trauma in addition to the New Orleans/Charity Rule (NOC). Both the CCHR and the NOC have demonstrated 100% sensitivity for ruling out intracranial injuries that would require neurosurgical intervention. One trial found the NOC more sensitive for detecting clinically significant intracranial injuries (99.4% versus 87.3%) but a decreased specificity (5.6% versus 39.7%) compared to the CCHR. The NOC is less complex than the CCHR but much less specific than the CCHR in all settings. The decrease in specificity can be attributed to the NOC's broad questions, such as "Any trauma above the clavicles."

The Canadian CT Head Rule (CCHR) is a well-validated clinical decision aid that assists clinicians in determining which minor head injury patients need head CT imaging. The criteria allow clinicians to safely rule out the presence of clinically important traumatic brain injuries among adult head injury patients without the need for CT imaging. Consider the PECARN Pediatric Head Injury/Trauma Algorithm for patients < 19 years old.

Recommendations & Criteria

¹Signs of basilar skull fracture

• Hemotympanum
• Racoon eyes
• Battle's sign
• CSF otorrhea or rhinorrhea

²Dangerous mechanism

• Pedestrian struck by motor vehicle 
• Occupant ejected from motor vehicle
• Fall > 3 feet or > 5 stairs

Management Considerations

If CT is negative and patient is referred for outpatient follow-up, consider the following recommendations:

• Provide reassurance, education and strict return precautions. 
  • CDC patient handout: Mild Traumatic Brain Injury and Concussion 
• Discuss post-concussive symptoms and clinical course. 
  • Headache
  • Balance problems or dizziness
  • Sound and light sensitivity
  • Feeling agitated or irritable
  • Confusion, concentration or memory problems
• Discuss brain bleed symptoms. Go to the ED if you experience any of these symptoms:
  • Drowsiness or inability to wake up
  • Worsening headache
  • Slurred speech, weakness, numbness, or decreased coordination
  • Repeated vomiting or seizures
  • Unusual behavior
• Follow-up with primary care, sports medicine or neurologist as indicated.

Provider Resources

• Concussion awareness, diagnosis and treatment (AAFP)

For patients < 19 years, consider the PECARN Pediatric Head Injury/Trauma Algorithm.