EBQ:Canadian Head CT Rule
PubMed Full text PDF
Contents
Clinical Question
Can a decision rule be used to determine which patients require CT imaging after head trauma?
Conclusion
The Canadian CT head rule is a effective method for determining the need for a patient to receive a non contrast brain CT after head trauma.
Major Points
The trial found that the following criteria had 100% sensitivity for identifying patient at risk for neurologic intervention with minor head injury
- GCS score <15 at 2h post injury
- Suspected open or depressed skull fracture
- Any sign of basal skull fracture (hemotympanum, ‘racoon’ eyes, cerebrospinal fluid otorrhoea/rhinorrhoea, Battle’s sign)
- Vomiting ≥ 2episodes
- Age ≥ 65 years
- Minor head injury is defined as witnessed loss of consciousness, definite amnesia, or witnessed disorientation in a patients with a GCS score of 13–15
The moderate risk group (for brain injury on CT) was identified with 95% sensitivity if any of the following were present:
- Amnesia before impact >30 min
- Dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height >3 feet or five stairs)
Design
- Prospective cohort study in 10 Canadian community and teaching institutions
- N=3121
Population
Inclusion Criteria
- Blunt Trauma to the head causing witnessed loss of consciousness, definite amnesia, or witnessed disorientation)
- GCS ≥ 13 on ED arrival
- Head injury within the last 24 hours
Exclusion Criteria
- Less than 16 years old
- Minimal head injury (no loss of consciousness, amnesia, or disorientation)
- No clear history of trauma as the primary event (eg, primary seizure or syncope)
- Obvious penetrating skull injury or obvious depressed fracture
- Acute focal neurological deficit
- Unstable vital signs associated with major trauma
- Seizure before assessment in the ED
- Bleeding disorder
- Using oral anticoagulants
- Returned for reassessment of the same head injury
- Pregnant
Baseline Characteristics
- Mean age: 38 years
- Age range 16-99
- Men: 69%
- Mean time between injury and physician assessment: 3.1 hours
- Arrival by ambulance: 73%
- Transfer from outside hospital: 13%
- Witnessed loss of consciousness: 46%
- Amnesia: 87%
- Initial GCS score:
- 15: 80%
- 14: 17%
- 13: 4%
- Mechanism of injury:
- Fall: 31%
- MVA: 26%
- Assault: 11%
- Sports: 10%
- Bicycle: 7%
Interventions
- Patients underwent standard CT of the head according to the judgment of the treating physician.
- The reliability of the radiography interpretations was assessed by having abnormal CT scans, and 5% (randomly selected) of normal scans reviewed by a second radiologist who was unaware of the first interpretation.
- Patients were classified as having no clinically important brain injury if af 14 days they had:
- no complaints of memory or concentration problems
- no seizures
- NO focal motor findings
- Score ≤ 10 on the Katzman Short Orientation-Memory-COncentration Test
- Returned to normal daily activities
Outcomes
High risk by decision rule, requiring neurological intervention: Sensitivity 100% (95% CI 92-1000) Specificity 68.7% (95% CI 67-70%)
With 2 moderate risk criteria added in (consisting of 7 criteria): Sensitivity 98.4% (95% CI 96%-99%) Specificity 49.6% (95% CI 48-51%)
Criticisms
Funding
Funded by peer-reviewed grants from the Medical Research Council of Canada (MT-13699) and the Ontario Ministry of Health Emergency Health Services Committee (11896N)
