Suspected Cervical Spine Injury in a Patient with Ankylosing Spondylitis
A 68-year-old male with a 20-year history of ankylosing spondylitis (AS) presents to the emergency department after a ground-level fall at home. He tripped on a rug and fell forward, striking his forehead. He did not lose consciousness but complains of neck pain and stiffness. On examination, he is alert and oriented, vital signs stable, and has midline cervical tenderness. He has limited cervical range of motion at baseline due to AS. The emergency physician orders cervical spine radiographs, which show no obvious fracture but are difficult to interpret due to the fused spine and osteopenia. The patient is anxious about radiation exposure and asks if he really needs a CT scan. The ED has a CT scanner available, but the patient is concerned about cost and radiation. He has Medicare and supplemental insurance. The physician is considering clearing his cervical spine clinically using the Canadian C-Spine Rule.
1. Can the Canadian C-Spine Rule be applied to this patient? Why or why not?
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No, the Canadian C-Spine Rule (CCR) should not be applied to this patient.
Rationale:
- The CCR is validated for alert (GCS 15) and stable trauma patients with neck pain and no high-risk factors. However, it has exclusion criteria, including:
- Age ≥65 years (this patient is 68).
- Paresthesias in extremities.
- Prior cervical spine surgery.
- Known cervical spine disease (e.g., ankylosing spondylitis, rheumatoid arthritis, osteopenia).
- Patients with AS are at high risk for unstable cervical spine fractures even with minor trauma due to the fused, rigid spine and altered biomechanics. The CCR does not have sufficient sensitivity in this population; therefore, it cannot be used to rule out fracture.
- The NEXUS criteria also exclude patients with altered mental status, intoxication, focal neurologic deficit, or distracting injury, but not specifically AS. However, NEXUS has not been validated in AS either.
Conclusion: The CCR is not applicable. The patient requires imaging, likely CT, to rule out fracture.
2. What is the most appropriate imaging strategy for this patient, and how would you address his concerns about radiation and cost?
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Imaging strategy:
- CT scan of the cervical spine is the imaging modality of choice for suspected cervical spine injury in patients with AS. Radiographs have low sensitivity in AS due to osteopenia, fused segments, and difficulty in positioning. CT has higher sensitivity and specificity for fractures and can detect subtle injuries.
- MRI may be indicated if there is neurologic deficit or suspicion of ligamentous injury or epidural hematoma, but CT is first-line.
- Flexion-extension views are contraindicated in the acute setting due to risk of worsening injury.
Addressing concerns:
- Radiation: Explain that the radiation dose from a cervical CT is relatively low (approximately 1-2 mSv) and the risk of missing a fracture in AS is high, with potential for catastrophic neurologic injury. The benefit outweighs the risk.
- Cost: Reassure that Medicare and supplemental insurance likely cover the CT. If cost is a concern, social work or financial counseling can be consulted. Emphasize that the cost of missed injury (e.g., paralysis, surgery) far exceeds the cost of CT.
- Shared decision-making: Discuss the rationale, risks, and benefits with the patient. Document the conversation.
Alternative: If CT is unavailable, MRI or careful clinical observation with immobilization may be considered, but CT is preferred.
3. If the CT is negative for fracture, can the patient be cleared clinically? What further steps are necessary?
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If CT is negative:
- A negative CT alone may not be sufficient to clear the cervical spine in patients with AS, because they are at risk for ligamentous injury and instability that may not be visible on CT. However, CT is highly sensitive for fractures.
- Clinical clearance: The patient should be evaluated for neurologic deficits, and if none, and CT is negative, the cervical spine can be cleared clinically if the patient is alert, not intoxicated, and has no distracting injury. However, given the high risk of instability in AS, some experts recommend MRI to rule out ligamentous injury or epidural hematoma, especially if there is persistent pain or neurologic symptoms.
- Immobilization: Keep the patient in a rigid cervical collar until cleared. If cleared, remove the collar and assess for comfort.
- Follow-up: Advise the patient to return if symptoms worsen. Provide education on safe mobility and fall prevention.
- Documentation: Document the clearance decision and rationale.
Conclusion: Negative CT in a patient with AS with no neurologic deficit and normal mental status may allow clinical clearance, but a low threshold for MRI is prudent. Shared decision-making with the patient is essential.