What is the appropriate workup for a C1-C2 (cervical spine) subluxation without dislocation and no pain?

Workup for C1-C2 Subluxation Without Dislocation and No Pain

The appropriate workup for a C1-C2 subluxation without dislocation and no pain should include plain radiographs supplemented by thin-cut CT with sagittal reconstruction, which provides a false negative rate of less than 0.1% for detecting cervical spine injuries. 1

Initial Imaging

Plain Radiographs

• Begin with a three-view cervical spine series (AP, lateral, and odontoid views) as the first step in evaluation 1
• Plain films alone have a sensitivity of only 54.3% for cervical injuries and may miss up to 15% of injuries on lateral view alone 1
• A lateral radiograph can detect most ligamentous injuries (96.8%) at the C1-C2 level 1

CT Imaging

• Follow plain films with thin-cut CT imaging (1.5-2mm collimation) with sagittal reconstruction through suspicious or inadequately visualized areas 1
• CT is superior for detecting bony abnormalities and should be performed for any abnormal or ambiguous findings on radiographs 1
• Consider entire cervical spine CT scanning rather than directed CT, as up to 31% of injuries may have non-contiguous cervical spine injuries 1
• Dynamic CT scanning may be particularly valuable for diagnosing rotatory subluxation 2

Advanced Imaging

MRI Evaluation

• MRI should be considered when:
  • There are neurological deficits 1
  • There is suspicion of spinal cord compression 3
  • Ligamentous injury needs further evaluation 1
• MRI is the modality of choice for evaluating the posterior ligamentous complex, though its sensitivity and specificity are lower than previously thought 1

Vascular Imaging

• Consider CT angiography (CTA) if there is concern for vertebral artery involvement 1
• Risk factors for vascular injury include fractures involving the transverse foramen, traumatic facet dislocations, and fractures of C1-C3 1

Special Considerations

Dynamic Studies

• For patients with no pain but persistent subluxation, dynamic studies may be necessary to evaluate stability 1, 2
• Dynamic CT scanning and 3D CT reconstruction are recommended for evaluating rotatory subluxation, especially in cases without clear trauma history 2

Neurological Assessment

• Thorough neurological examination is essential, with special attention to:
  • Superficial abdominal reflexes (absence correlates with cord compression) 3
  • Bladder dysfunction (highly correlates with cord compression) 3
  • Upper extremity dysesthesia or weakness 4

Pitfalls and Caveats

• A single lateral plain film alone is insufficient for clearing the cervical spine in cases of subluxation 1
• Normal variants in children under 8 years can mimic pathology (pseudosubluxation of C2-C3, widening of the atlantodental interval) 1
• Isolated ligamentous injury without fracture occurs in approximately 0.1-0.7% of blunt trauma patients but can lead to significant instability if missed 1
• Even in asymptomatic patients, unstable injuries may be present; the combination of plain films and CT has been shown to detect all ligamentous injuries in some studies 1
• For chronic C1-C2 subluxation, more extensive imaging workup may be required before considering surgical intervention 5