From the Guidelines
The Canadian CT Head Rule (CCHR) has the highest sensitivity and specificity for detecting minor head injury requiring neurosurgical intervention or at risk of intracranial injury in adult patients. This rule has a sensitivity of approximately 99-100% and specificity of 48-77% for detecting injuries requiring neurosurgical intervention 1. The CCHR identifies high-risk patients who need immediate CT scanning based on five criteria: GCS score less than 15 at two hours after injury, suspected open or depressed skull fracture, signs of basal skull fracture, vomiting more than twice, or age over 65 years. Medium-risk factors include amnesia before impact for more than 30 minutes and dangerous mechanism of injury.
Some key points to consider when using the CCHR include:
- The rule is highly sensitive and specific for detecting clinically important brain injuries, making it a valuable tool in emergency departments where rapid assessment of head injuries is crucial.
- The CCHR has been extensively validated in multiple settings, including a study published in 2023 that demonstrated its effectiveness in reducing unnecessary CT scans while maintaining high sensitivity for detecting significant intracranial injury 1.
- Other decision rules, such as the New Orleans Criteria and NEXUS-II, have lower specificity and may lead to more unnecessary testing, making the CCHR the preferred tool for determining the need for head CT in minor head injury 1.
- The CCHR is only valid when applied to patients who have had loss of consciousness or amnesia, or disorientation, and who are not on anticoagulants, highlighting the importance of careful patient selection when using this rule.
Overall, the CCHR is a reliable and effective tool for identifying adult patients with minor head injury who require neurosurgical intervention or are at risk of intracranial injury, and its use can help reduce unnecessary CT scans while maintaining high sensitivity for detecting significant injuries.
From the Research
Clinical Decision Rules for Minor Head Injury
The Canadian Computed Tomography Head Rule (CCHR) is a widely researched and validated decision rule for detecting minor head injury requiring neurosurgical intervention or at risk of intracranial injury in adult patients.
- The CCHR has a high sensitivity of 99% to 100% and specificity of 48% to 77% for injury requiring neurosurgical intervention 2.
- A study published in the Lancet found that the CCHR high-risk factors were 100% sensitive for predicting need for neurological intervention, and would require only 32% of patients to undergo CT 3.
- The CCHR has been externally validated in several studies, including a prospective multicenter study in the Netherlands, which found that the CCHR had a sensitivity of 100% for neurosurgical intervention and a specificity of 37.2% to 39.7% for neurocranial traumatic findings 4.
- Another study published in the BMJ found that the CCHR had a sensitivity of 96% and specificity of 55% for any intracranial traumatic finding on CT, and a sensitivity of 100% and specificity of 55% for a potential neurosurgical lesion on CT 5.
Comparison with Other Decision Rules
Other decision rules, such as the New Orleans Criteria (NOC) and the National Emergency X-Radiography Utilization Study II (NEXUS II), have also been studied and validated for detecting minor head injury.
- The NOC has a higher sensitivity for neurocranial traumatic findings and for clinically important findings, but lower specificity compared to the CCHR 4.
- The NEXUS II criteria have a sensitivity of 99% and specificity of 25% for clinically important brain injury, but have not been as widely validated as the CCHR 2.
- A study published in the BMJ found that the CHIP rule, NOC, CCHR, and NICE guideline for head injury all had varying degrees of sensitivity and specificity for detecting intracranial traumatic findings and potential neurosurgical lesions, and that the choice of decision rule depended on the threshold for performing CT scanning 5.