Unstable subaxial cervical spine injury with normal computed tomography and magnetic resonance initial imaging studies: a report of four cases and review of the literature.

STUDY DESIGN: Case series.

OBJECTIVE: To describe 4 cases of unstable subaxial cervical spine injury not demonstrated with initial radiograph, computed tomography (CT), and magnetic resonance (MR) imaging.

SUMMARY OF BACKGROUND DATA: When evaluating the cervical spine for ligamentous or osseous injuries in the blunt trauma patient population, negative predictive value measurements of 100% for CT and MR imaging have been published. Unstable subaxial cervical spine injury has rarely been reported in the spine literature in conjunction with initial radiograph, CT, and MR imaging demonstrating no osseous or ligamentous injury. Historically, reports of subacute cervical spine instability following trauma exist and were presented before the availability of MR and multidetector CT imaging.

METHODS AND RESULTS: We report 4 examples of unstable subaxial cervical spine injury each with initial imaging interpreted as negative. All 4 cases presented at a level-one tertiary care facility. Follow-up radiographs demonstrated unstable cervical spine injuries requiring surgical stabilization.

CONCLUSION: Notwithstanding high sensitivities, specificities, and negative predictive values for cervical spine imaging and "clearance" mechanisms, 4 cases that illustrate the potential for undetected unstable cervical spine injuries are presented. Tremendous advancements in medical imaging have been made. However, radiograph, CT, and MR imaging may still fail to accurately translate the anatomic and dynamic complexity of the cervical spine into digital images that accurately guide clinical practice. A full understanding of and keen appreciation for the fact that no imaging technique, classification method, or clearance protocol can produce 100% sensitivity at all times is essential. These case reports cumulatively demonstrate a 0.04% to 0.2% incidence of undetected cervical injury requiring surgical stabilization. Removing cervical collar immobilization as quickly as possible based on negative interpretation of imaging data may prove harmful in a measurable percentage of patients and must be undertaken with caution only after clinical correlation and strict follow-up is established.