The workup hinges on whether there is concern for ligamentous instability versus a simple soft tissue injury. The approach differs based on the clinical scenario:
1. Initial Clinical Assessment
Clinical decision rules — NEXUS and the Canadian C-Spine Rule (CCR) — determine whether imaging is needed at all. If the patient is alert, non-intoxicated, has no midline tenderness, no focal neurologic deficit, and no distracting injury, imaging can be safely deferred. [1]
Red flags warranting further workup include:
Midline cervical tenderness on palpation
Neurologic symptoms (radiculopathy, myelopathy, weakness)
Mechanism suggesting high-energy injury (e.g., high-speed MVC, axial loading)
2. CT Cervical Spine (Initial Imaging of Choice)
CT without contrast is the reference standard for initial evaluation, with sensitivity approaching 98–100% for clinically significant injuries. [1-2]
It has supplanted plain radiographs, which have a sensitivity of only ~36%. [2]
CT effectively identifies fractures, subluxation, and indirect signs of ligamentous injury (e.g., widened interspinous distance, facet joint widening).
3. MRI Cervical Spine (When Ligamentous Injury Is Suspected)
MRI is the most sensitive modality for detecting ligamentous injury, including disruption of the anterior/posterior longitudinal ligaments, interspinous ligaments, and disc herniation. [3-4]
The ACR Appropriateness Criteria recommend MRI as the next study when clinical or imaging findings suggest ligamentous injury after CT.
However, important caveats exist:
MRI has a false-positive rate of 25–40% and tends to overestimate ligamentous injury severity (specificity 64–77%). [2-3]
In the absence of neurologic symptoms, CT combined with clinical exam is often sufficient to rule out clinically significant injuries. [2]
MRI rarely changes management when CT is negative and the patient is neurologically intact. [1-2]
4. Flexion-Extension Radiographs — Limited Role
The literature has been uniformly negative regarding the utility of flexion-extension radiographs in the acute trauma setting. [3][5]
Key limitations include:
Muscle spasm limits motion acutely, reducing sensitivity
Inadequate image quality in 30–70% of cases [5]
Instability may only manifest at endpoints of motion that patients cannot achieve acutely [2]
Flexion-extension views may have a limited supplementary role when MRI findings are equivocal, or for follow-up assessment of patients with persistent neck pain and negative MRI. [2-3]
The following figure demonstrates dynamic cervical instability on flexion-extension views, illustrating the type of pathologic motion that these studies aim to detect
