Nexus Criteria Calculator

NEXUS is not a score but a rule-out instrument: all five criteria must be absent before the cervical spine can be cleared without imaging. The five are focal neurological deficit, midline posterior cervical tenderness, altered level of alertness, evidence of intoxication, and a painful distracting injury. The logic is that a fully alert, sober patient with no neurological signs who reports no midline tenderness and has nothing else competing for their attention is a reliable reporter of their own spine, so the physical examination substitutes for radiography. Midline tenderness means palpation over the spinous processes from the nuchal ridge to the first thoracic vertebra; paraspinal muscular tenderness alone does not count. A distracting injury is one painful enough to mask neck pain, typically a long bone fracture, a large laceration or degloving, a crush injury or visceral pain, and clinical judgement decides the borderline cases. Reported sensitivity for clinically significant cervical spine injury is about 99.6 percent, meaning roughly one significant injury in 250 is missed, but specificity is low at around 12.9 percent, so the rule mainly authorises omitting imaging in the clearly well rather than reducing scanning across the board. Elderly patients are the main pitfall: degenerative spondylosis produces baseline midline tenderness that makes the criterion positive without acute injury, while osteoporosis and ankylosing spondylitis raise the consequence of a missed fracture, so a lower imaging threshold and CT rather than plain films are appropriate. The rule assumes blunt trauma and was not designed for penetrating injury.

The National Emergency X-Radiography Utilization Study was led by Jerome Hoffman at UCLA and ran as a prospective observational study across 21 emergency departments in the United States. A pilot study published in 1998 proposed the five criteria; the definitive validation, enrolling 34,069 blunt trauma patients who underwent cervical spine radiography, appeared in the New England Journal of Medicine in July 2000. Of those patients, 818 had radiographically documented cervical spine injury, and the decision instrument identified all but two of the 578 classified as clinically significant. The motivation was volume-driven: cervical spine radiography had become near-reflexive after blunt trauma, generating enormous cost and radiation exposure for an injury prevalence of roughly 2 percent. A competing rule appeared almost simultaneously. Ian Stiell and the Canadian group, who had already produced the Ottawa ankle and knee rules, published the Canadian C-Spine Rule in JAMA in 2001, built around dangerous mechanism, age 65 and over, paraesthesias, and the ability to rotate the neck 45 degrees in each direction. A head-to-head comparison by Stiell and colleagues in the New England Journal of Medicine in 2003 found the Canadian rule more sensitive and considerably more specific in alert, stable patients, though NEXUS remained simpler to apply and covers populations the Canadian rule explicitly excludes. Both rules are now embedded in emergency department protocols, and the practical debate has shifted as multidetector CT displaced plain radiography as the imaging modality of choice.