The NEXUS rule provides a binary outcome: the cervical spine can be cleared clinically, or imaging is required. If all five criteria are absent (no posterior midline cervical tenderness, no focal neurological deficit, normal alertness, no intoxication, and no painful distracting injury), the c-spine can be cleared without imaging. The probability of a clinically significant cervical spine injury in this scenario is extremely low (negative predictive value of 99.8% in the original study of over 34,000 patients).

If any single criterion is present, the c-spine cannot be cleared clinically and imaging is recommended. The choice of imaging modality (plain radiographs vs. CT) depends on clinical context and institutional protocols, though CT has largely replaced plain films in most trauma centers due to superior sensitivity for fractures. The presence of multiple positive criteria increases the pre-test probability of injury but does not change the binary recommendation.

Use the NEXUS criteria for any trauma patient in the emergency department when you need to determine whether cervical spine imaging is necessary. The rule is applicable across all ages and mechanisms of injury, making it more broadly applicable than the Canadian C-Spine Rule (which has specific age and mechanism restrictions). It is particularly useful in busy emergency departments where rapid clinical clearance of the c-spine can expedite patient flow.

The NEXUS criteria should be applied during the secondary survey after life-threatening injuries have been addressed. The rule is most valuable when the clinician is considering whether imaging can be safely avoided. In patients with obvious high-energy mechanisms or clinical instability, imaging is typically obtained regardless of the rule. The rule's simplicity (five yes/no criteria) makes it easy to remember and apply without a calculator.

The NEXUS criteria have several recognized limitations. The definition of 'distracting injury' is subjective and not precisely defined in the original study, leading to inconsistent application among clinicians. What constitutes a distracting injury remains a matter of clinical judgment. The 'altered alertness' criterion is also somewhat vague and may be interpreted differently by different providers.

The NEXUS study had a 99.6% sensitivity, meaning it missed 8 of 818 injuries in the original cohort. While none of the missed injuries required surgical intervention, any missed cervical spine injury is a significant medicolegal concern. The Canadian C-Spine Rule has demonstrated slightly better sensitivity and specificity in comparative studies. Additionally, NEXUS was validated primarily in the era of plain radiographs, and its performance characteristics may differ in the current era of CT as the primary imaging modality. The rule does not perform as well in elderly patients (age over 65), where the Canadian C-Spine Rule may be preferred.