Background

Neck pain after blunt trauma is common but significant cervical spine injuries are not. An unrecognized cervical spine injury can be catastrophic as it can lead to serious neurologic disability or even death. As a result, we as clinicians are fairly liberal about performing imaging of the cervical spine after trauma. Prior to the creation of the NEXUS C-spine criteria and the Canadian C-spine criteria, clinicians had little to guide their use of imaging. However, the advent of these decision instruments can help to eliminate some unnecessary testing while concomitantly ensuring that significant injuries aren’t missed.

Any decision instrument that would be usable by providers would have to have a near 100% sensitivity for picking up clinically significant injuries. To this end, clinicians will accept a low specificity and we understand that we will end up ordering hundreds if not thousands of C-spine imaging tests for every fracture we find.

Clinical Question

Can the NEXUS C-spine decision instrument identify patients at an extremely low risk for c-spine injury after blunt trauma and reduce the need for imaging?

Population

All patients with blunt trauma who underwent radiography of the cervical spine

Intervention

The NEXUS Decision Instrument (no midline c-spine tenderness, no focal neuro deficit, normal alertness, no intoxication, and no painful, distracting injury)

Control

Standard C-spine imaging for all trauma patients

Outcomes

Performance characteristics (sensitivity, specificity, NPV, PPV) of the NEXUS decision instrument

Design

Prospective, multicenter, observational study

Excluded

Penetrating trauma, c-spine imaging for any other reason unrelated to trauma

Primary Results

  • 34,069 patients included in this analysis
  • 818 of 34,069 patients had C-spine injuries

Critical Findings

  • NEXUS instrument identified 810 of 818 injuries (99%)
  • Sensitivity 99% (CI 98-99.6) NPV 99.8% (99.6-100)
  • Specificity 12.9% PPV 2.7%
  • Only 2 of the 8 patients missed by NEXUS had clinically significant injuries
  • Sensitivity for clinically important injuries: 99.6% (98.6-100) NPV 99.9%
  • Overall, use of the instrument would have reduced imaging by 12.6% (4309 cases)

Strengths

  • Large, multicenter trial
  • Study asked a clear clinical question that was patient centered
  • Distinguished between clinically significant and clinically insignificant injuries
  • Showed a robust reduction in imaging with implementation of this instrument
  • Minimal exclusion criteria makes the results generalizable to most patient populations

Limitations

  • The majority of patients had C-spine x-rays performed and not CT scans. X-rays are uncommonly performed in adult patients with a concern for c-spine today
  • The decision instrument was not perfect with a lower limit of sensitivity of 98%. Missing up to 2% of injuries may be too risky for some providers
  • “Distracting injuries” was not explicitly defined in this study or in the derivation study. What a distracting injury is continues to be debated today.

Author's Conclusions

“A simple decision instrument based on clinical criteria can help physicians to identify reliably the patients who need radiography of the cervical spine after blunt trauma. Application of this instrument could reduce the use of imaging in such patients.”

Our Conclusions

We agree with the author’s conclusions. The NEXUS C-spine decision instrument is extremely sensitive for determining which patients should have imaging performed after neck trauma. It’s important to note that this decision tool is a 1-way instrument - it tells you who should not be imaged but positive criteria doesn’t mean you HAVE to image the patient since specificity is very low. Appropriate application of this instrument would significantly reduce c-spine imaging in the ED but improper application could paradoxically increase imaging.
The authors additionally note that no decision instrument is perfect and that NEXUS would have missed cervical injuries in 1 in 4000 patients to whom it was applied. Based on the number of blunt traumatic neck pain patients seen per year, they estimate that there would be 1 missed fracture for every 125 physician years in practice.

Potential Impact To Current Practice

The NEXUS C-spine decision instrument has been widely adopted and is widely taught to both medical students and residents particularly in Emergency Medicine and trauma surgery. Additionally, many EMS systems have adopted these criteria for clearing cervical spines in the field prior to transport. The derivation article for NEXUS was named one of ALiEM’s Landmark Articles.

Bottom Line

The NEXUS C-spine decision instrument his highly sensitive for picking up cervical spine injuries in patients with trauma. Application of this instrument will reduce imaging without missing a significant number of c-spine injuries.