This calculator is for general information and education. It is not medical advice and does not replace the judgment of a doctor, nurse or pharmacist who knows the full clinical picture.
Who needs a neck scan after an injury?
After a car crash, a fall or a sports injury, emergency teams must decide whether to image the cervical spine. Missing a fracture can lead to paralysis, but scanning everyone exposes patients to radiation, costs time and money and fills scanners. The NEXUS study, the National Emergency X-Radiography Utilization Study, followed 34,069 patients at 21 US emergency departments and published a simple rule in 2000.
The five low-risk criteria
Imaging is not needed if the patient has none of the following:
- Midline tenderness: pain when pressing on the back of the neck, along the spine.
- Intoxication: alcohol or drugs, judged by history or examination.
- Altered alertness: a Glasgow score below 15, disorientation, delayed or inappropriate answers.
- Focal neurologic deficit: weakness, numbness or tingling in a limb.
- Painful distracting injury: one severe enough to mask neck pain, such as a long-bone fracture, a large laceration, a burn or a crush injury.
If any is present, cervical spine imaging is indicated. In adults, CT is now preferred to plain X-rays.
Accuracy
In the original study, 818 patients had a cervical spine injury, 578 of them clinically significant. The rule flagged 576 of those 578, a sensitivity of 99.6%, and would have avoided imaging in 12.6% of patients. Its specificity is low, about 13%, which is expected for a rule designed never to miss an injury.
Worked example
A 34-year-old cyclist is brought in after a fall. He is fully alert and sober, says his neck feels stiff but has no pain when the midline is pressed, moves all limbs normally and has only abrasions on his arm. None of the five criteria is present, so no imaging is needed. If he had a painful wrist fracture, that would count as a distracting injury, and imaging would be indicated.
NEXUS and the Canadian C-spine rule
The Canadian C-spine rule, published in 2001, adds high-risk factors (age 65 or more, a dangerous mechanism, numbness in the limbs) and a test of active neck rotation. In a 2003 comparison it was more sensitive and more specific than NEXUS, but it only applies to alert, stable adults. Many emergency departments use either rule; both are much safer than imaging on instinct.
Limits
NEXUS applies only to blunt trauma, not penetrating injuries. In older adults, whose fractures can occur with little force, many clinicians have a lower threshold for imaging. Whatever the score, persistent pain or new symptoms should prompt reassessment.