What are the key considerations and treatment options for a patient with chronic C1-C2 (cervical spine) subluxation?

Chronic C1-C2 Subluxation: Key Clinical Considerations

For chronic C1-C2 subluxation, immediately assess for spinal cord compression using CT cervical spine followed by MRI, maintain rigid cervical collar immobilization, and refer urgently for neurosurgical evaluation if neurological signs are present or if the atlanto-dental interval exceeds 5mm. 1, 2

Immediate Assessment Priorities

Neurological Examination

• Check for absent superficial abdominal reflexes and bladder dysfunction history, as these correlate highly with spinal cord compression 2
• Assess for progressive myelopathy signs: hyperreflexia, clonus, Babinski sign, gait disturbance, and upper motor neuron findings 1, 2
• Document any radicular symptoms, though these are less common than myelopathic findings in C1-C2 pathology 3

Imaging Protocol

• Order CT cervical spine without contrast as the initial study to measure the atlanto-dental interval (ADI) and assess bony anatomy 1, 4
• Follow with MRI cervical spine with contrast to evaluate spinal cord compression, defined as loss of posterior subarachnoid space 3, 2
• Obtain dynamic flexion-extension radiographs only if no instability is evident on static imaging and neurological exam is normal 5, 3
• CT demonstrates spinal cord compression better than plain radiographs and correlates more accurately with clinical neurological status 2

Critical Measurements and Red Flags

Radiographic Thresholds

• ADI >5mm indicates significant subluxation requiring intervention 2
• Loss of posterior subarachnoid space on CT or MRI indicates cord compression and mandates urgent surgical referral 2
• Assess for associated odontoid erosions, pannus formation, or ligamentous injury 5, 6

High-Risk Features Requiring Immediate Action

• Progressive neurological deficit requires surgical decompression within 24 hours 3
• Fixed subluxation that does not reduce with positioning indicates chronic instability 7, 8
• Presence of myelopathy with cord compression on imaging 2

Stabilization and Protection

Immobilization Strategy

• Apply rigid cervical collar immediately and maintain continuously until definitive treatment 1, 6
• Avoid cervical manipulation or aggressive physical therapy due to instability risk 3, 6
• For patients with inflammatory arthritis (rheumatoid, enthesitis-related), cervical collar protection is essential even during medical management 6

Hemodynamic Management

• Maintain mean arterial pressure ≥70 mmHg if any neurological compromise exists, as hypotension worsens spinal cord ischemia 1
• Place arterial line for continuous monitoring if myelopathy is present 1

Treatment Decision Algorithm

Conservative Management (Limited Role)

• Conservative treatment is only appropriate for patients with ADI <5mm, no cord compression, and no neurological deficits 6, 2
• NSAIDs for pain control in inflammatory causes 6
• Cervical halter traction may be attempted only after severe inflammation is excluded and only in reducible subluxations 6
• Monitor closely for neurological deterioration, as progression can occur despite collar immobilization 6

Surgical Indications (Most Patients)

• ADI ≥5mm with or without symptoms 2
• Any evidence of spinal cord compression on imaging 2
• Progressive or persistent neurological deficits 3, 1
• Fixed subluxation that fails conservative reduction attempts 7, 8
• Chronic subluxation with persistent pain and functional impairment despite 3+ months of conservative care 3, 6

Surgical Options

• C1 lateral mass screws with C2 pedicle screws (Harms construct) is the preferred technique for isolated C1-C2 subluxation 9, 7
• Occipital-cervical fusion is indicated when C1 lateral mass anatomy is inadequate (revision surgery, severe degeneration, or rheumatoid destruction) 9, 8
• C2 translaminar screws are an alternative to pedicle screws in pediatric patients or when pedicle anatomy is unfavorable 7
• Intraoperative CT guidance achieves 98% ideal screw placement accuracy 9

Common Pitfalls to Avoid

• Never delay imaging in patients with neck pain and known inflammatory arthritis (rheumatoid, ankylosing spondylitis, enthesitis-related arthritis), as C1-C2 subluxation is a recognized complication 6, 2
• Do not rely on plain radiographs alone; CT and MRI are essential for assessing cord compression 2
• Avoid prolonged conservative management (>3 months) in patients with significant subluxation, as chronic cases may develop fixed deformity requiring more extensive fusion 6, 7, 8
• Never remove cervical collar protection without neurosurgical clearance, even if symptoms improve 1, 6
• Do not assume absence of symptoms means absence of cord compression; neurological examination and imaging are mandatory 2

Urgent Referral Criteria

Refer immediately to neurosurgery or spine surgery for:

• Any neurological deficit 3, 1
• ADI ≥5mm 2
• Cord compression on imaging 2
• Failed conservative management after 6-8 weeks in low-risk patients 6
• Inflammatory arthritis with C1-C2 involvement 6