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    Canadian CT Head Injury/Trauma Rule

    Clears head injury without imaging.
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    INSTRUCTIONS

    Only apply to patients with Glasgow Coma Scale (GCS) 13-15 and at least one of the following:

    • Loss of consciousness.
    • Amnesia to the head injury event.
    • Witnessed disorientation.

    Exclusion criteria:

    • Age <16 years.
    • Blood thinners.
    • Seizure after injury.
    When to Use
    Pearls/Pitfalls
    Why Use
    • The Canadian CT Head Rule is a well-validated clinical decision aid that allows physicians to safely rule out the presence of intracranial injuries that would require neurosurgical intervention without the need for CT imaging.
    • The CCHR has been found to be 70% sensitive for “clinically important” brain injury in EtOH intox patients (Easter 2013).

    The Canadian CT Head Rule (CCHR) was developed to help physicians determine which minor head injury patients need head CT imaging.

    • The original validation trial and multiple subsequent studies (Stiell 2001, Stiell 2005, Stiell 2010) each found the CCHR’s High Risk Criteria to be 100% sensitive for injuries requiring neurosurgical intervention. It has an 87-100% sensitivity for detecting “clinically important” brain injuries that don’t require neurosurgery.
    • The rule excluded patients on oral anticoagulants and anti-platelet agents, so no data is available for these patients.
    • Patients with minimal head injury (i.e no history of loss of consciousness, amnesia, and confusion) generally do not need a CT scan). For example, patients over 65 years may not need a CT scan just based on their age if they do not have the history mentioned above. When a patient fails the CCHR, use clinical judgment on whether a CT scan is necessary.
    • One study found the CCHR the most consistent, validated, and effective clinical decision rule for minor head injury patients.

    Points to keep in mind:

    • While there is only one US validation study for the CCHR, it was 100% sensitive for clinically important injuries and injuries requiring neurosurgery.
    • A retrospective study in the United Kingdom found that applying the CCHR would have actually resulted in an increase in the number of patients undergoing CT scan in that particular practice setting.
    • There is debate about whether the goal should be to find all intracranial injuries or to find patient-important ones that would require neurosurgical intervention.

    There are more than 8 million patients who present annually to US Emergency Departments for evaluation of head trauma. The vast majority of these patients have minor head trauma that will not require specialized or neurosurgical treatment. At the same time, rates of CT imaging of the head have more than doubled from the early 1990s through the 2000s.

    Exclusion Criteria: If any of the following are true, the CCHR does not apply
    No
    Yes
    No
    Yes
    No
    Yes
    High Risk Criteria: Rules out need for neurosurgical intervention
    No
    0
    Yes
    +1
    No
    0
    Yes
    +1
    No
    0
    Yes
    +1
    No
    0
    Yes
    +1
    No
    0
    Yes
    +1
    Medium Risk Criteria: In addition to above, rules out “clinically important” brain injury (positive CT's that normally require admission)
    No
    0
    Yes
    +1
    No
    0
    Yes
    +1

    Result:

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    Next Steps
    Evidence
    Creator Insights

    Advice

    • Consider obtaining a CT scan if any questions in the rule are answered affirmatively.
    • This rule can only be applied to patients with LOC/Amnesia or changes in mental status.
    • The original study did not include subjects <16 years of age.

    Management

    • Remember to always discuss post-concussive symptoms and management with the patient, especially if discharging them without a head CT. Otherwise when they feel post-concussive symptoms they may worry a CT was necessary.
    • By educating them on the symptoms of injuries that require neurosurgical intervention vs. post-concussive symptoms, the patient can feel empowered and reassured.

    Critical Actions

    The Canadian CT Head Rules have been validated in multiple settings and have consistently demonstrated that they are 100% sensitive for detecting injuries that will require neurosurgery.

    • Depending on practice environment, it may not be considered acceptable to miss any intracranial injuries, regardless of whether they would have required intervention.
    • Providers may want to consider applying the New Orleans Criteria (NOC) for head trauma, as there has been at least one trial finding it to be more sensitive for detecting clinically significant intracranial injuries (99.4% vs 87.3%). Though this comes at the price of markedly decreased specificity (5.6% vs. 39.7%).
      • Furthermore, there are other trials in which the CCHR was found to be more sensitive than the NOC for detecting clinically important brain injuries.
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    Dr. Ian Stiell
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