Canadian C-Spine Rule
The Canadian C-spine Rule (CCR), described in Figure 2, is more complex than the NEXUS criteria, but there are data to suggest it performs better in head-to-head evaluations.18
Figure 2.
Patients were assessed primarily on the basis of the three-view X-rays used in the NEXUS validation, however, only 71.7% of patients received radiographs and the remainder of patients were assessed using a telephone survey the authors had created during the derivation phase.18 Some lesions were deemed to be clinically unimportant, including isolated osteophyte avulsion, isolated fracture of a transverse process not involving a facet joint, isolated fracture of a spinous process not involving the lamina, or simple compression fracture involving less than 25% of the vertebral body height.18
Unfortunately, the CCR validation study was limited by incomplete evaluation in 10% of cases, though multiple subgroup analyses consistently demonstrated the CCR was 95% sensitive or higher for detecting clinically important cervical spine injury, outperforming NEXUS. Subsequently, a large systematic review of 15 studies shows sensitivity of the CCR to be 90% to 100% and NEXUS to be 83% to 100%.19
Comment: The NEXUS criteria were validated in a larger and more heterogeneous cohort than CCR, and also have the advantage of being easier to remember. Using either rule, clinicians must consider that “clinically unimportant” cervical spine fractures are not excluded. Ultimately, the landscape of cervical spine assessment has shifted to performing CT over plain radiographs, and these rules should be re-evaluated in this context.20
Blunt Chest Trauma
NEXUS Chest Guidelines
The NEXUS chest guidelines are more recent developments to help assess the need for chest imaging in the patient presenting with a blunt trauma. The first rule derived and validated by the investigators examined the utility of seven clinical criteria in predicting the need for chest imaging—either X-ray or CT:
- Patients older than age 60 years;
- Rapid deceleration mechanism defined as fall greater than 20 feet or motor vehicle crash greater than 40 mph;
- Chest pain;
- Intoxication;
- Abnormal alertness/mental status;
- Painful distracting injury; and
- Chest wall tenderness to palpation, with the exception of isolated clavicular tenderness to palpation.21
Of note, pericardial tamponade and cardiac contusion were not studied as they “are not primarily diagnosed by chest X-ray (CXR) or chest CT.”21 The NEXUS chest validation cohort included over 9,000 blunt trauma patients older than age 14 years receiving a variety of imaging modalities, but 43% received only a single CXR. The presence of one or more of the criteria had a sensitivity of 98.8% for detecting any traumatic injury on chest imaging, as well as a sensitivity of 99.7% for any major injury.
CT-All Rule and CT-Major Rule
Subsequently, the investigators of the NEXUS chest rule focused on creating a decision rule to decrease chest CT utilization in blunt trauma, as they found chest CT after a normal CXR to be low-yield.22 After classifying injuries as major or minor based on the necessity of procedural intervention, the authors derived two rules: CT-All, designed to not miss any injuries; and CT-Major, to identify major injuries requiring procedural intervention.
Hemothorax, pneumothorax, pneumomediastinum, or pulmonary contusion that were found on CT but did not require inpatient observation, intervention, or mechanical ventilation were considered clinically insignificant.23
The CT-Major includes six factors:
- Abnormal CXR showing any thoracic injury including clavicle fracture or widened mediastinum;
- Distracting injury;
- Any chest wall tenderness;
- Sternum tenderness;
- Thoracic spine tenderness; or
- Scapular tenderness.
The CT-All includes all of the CT-Major criteria and the additional criteria of rapid deceleration mechanism as defined previously. The validation cohort included over 5,000 patients aged 14 years and older. Having one or more of the major criteria was found to be 99.2% sensitive for major injury, and meeting one or more of the CT-All criteria were found to be 95.4% sensitive for any clinically significant injury. Both CT-Major and CT-All rules identified all 21 aortic/great vessel injuries in their study; the authors assert that vigilance for these types of injuries is often the primary justification for ordering CT imaging.23
Comment: Given the ubiquity and utility of the CXR, it seems unlikely that one would forgo a simple film on the basis of these rules. The presence of an abnormal CXR was by far the best screening criterion for major injury seen on subsequent chest CT, with sensitivity and specificity of 74.7% and 83.9%, respectively.24 Of note, focused assessment with sonography for trauma (FAST) or eFAST (extended FAST) examinations were reported in only 63% or fewer patients in the derivation phase, so the rules did not incorporate point of care ultrasound findings as a criterion despite the growing influence of this modality on trauma decision-making.23