CIM Case: Rheumatoid Arthritis - Cervical Spine

Clinical Scenario

Patient: 58-year-old female Presentation: 20-year history of seropositive rheumatoid arthritis, 6 months of progressive unsteadiness, occasional suboccipital headaches worse with neck movement, episodes of dizziness, one fainting spell Relevant history: On methotrexate and prednisolone, multiple joint replacements (bilateral THR, right TKR), poorly controlled inflammation recently (elevated CRP) Examination findings:

Obvious RA deformities - MCP subluxation, swan neck deformities, ulnar drift bilateral hands
Bilateral foot deformities (hallux valgus, claw toes)
Wide-based gait
Romberg positive
Upper limbs: Generalised weakness (4/5), difficult to assess due to joint disease
Lower limbs: Hyperreflexia bilateral (3+)
Hoffman's sign positive bilateral
Ankle clonus (3 beats bilateral)
Babinski upgoing bilateral
Sensation: Reduced proprioception lower limbs
Bladder: No incontinence, no urgency

Investigations Provided

Laboratory Results

Test	Result	Normal Range	Interpretation
Haemoglobin	108 g/L	120-160	Anaemia of chronic disease
WCC	7.2 × 10⁹/L	4-11	Normal
Platelets	385 × 10⁹/L	150-400	Normal
ESR	65 mm/hr	0-20	Elevated - active RA
CRP	42 mg/L	<5	Elevated - active inflammation
Rheumatoid factor	Positive (256 IU/mL)	<14	Seropositive RA
Anti-CCP	Positive (>300 U/mL)	<20	High titre - erosive disease
Creatinine	85 μmol/L	60-110	Normal (important for methotrexate)
ALT	35 U/L	<40	Normal (methotrexate monitoring)

Imaging

Image 1: Cervical Spine Radiographs - AP, Lateral, Flexion-Extension

Radiological features:

Neutral lateral:
- Atlantodental interval (ADI) = 6mm (normal <3mm)
- Posterior atlantodental interval (PADI) = 12mm (concerning <14mm)
- No obvious basilar invagination on lateral
Flexion view:
- ADI increases to 10mm
- Significant C1-C2 instability demonstrated
Extension view:
- ADI reduces to 4mm
- Dynamic instability confirmed
Subaxial spine:
- C3-4 and C4-5 subluxation ("stepladder" appearance)
- Disc space narrowing C4-5, C5-6
- No obvious basilar invagination

Image 2: MRI Cervical Spine with Brainstem

MRI findings:

Pannus formation around odontoid (soft tissue mass posterior to dens)
Moderate cord compression at C1-C2 level from pannus
Cord signal change (T2 hyperintensity) at C1-C2 level - myelomalacia
Subaxial stenosis C4-5 with mild cord compression
No cord signal change at subaxial level
Odontoid intact, no erosion through tip

Image 3: CT Cervical Spine

CT findings:

Erosion of odontoid peg laterally
C1-C2 facet erosions
No fracture
Lateral mass anatomy preserved (important for fixation planning)

Questions & Model Answers

What are the three patterns of cervical spine involvement in rheumatoid arthritis and how do they present?

What are the clinical features of cervical myelopathy in RA, and how do you grade severity?

What imaging would you order and what measurements are critical?

What are the indications for surgery in RA cervical spine? What procedure would you recommend for this patient?

What are the specific perioperative considerations in RA patients undergoing cervical spine surgery?

What are the expected outcomes and complications of surgery? How do you follow up these patients?

Key Teaching Points

Pattern Recognition

This pattern suggests RA Cervical Spine Involvement:

Longstanding seropositive RA with peripheral joint destruction
Suboccipital headache and neck pain
Myelopathic features (UMN signs) out of proportion to peripheral disease
Unsteadiness, gait abnormality
Vertebrobasilar symptoms (dizziness, fainting)

Three Patterns of Involvement:

Pattern	Frequency	Key Measurement	Surgical Concern
Atlantoaxial instability	65%	ADI, PADI	C1-C2 fusion
Basilar invagination	20-25%	Ranawat, McRae	Occipitocervical fusion
Subaxial subluxation	20-25%	>3.5mm translation	Extended fusion

Critical Management Points

PADI <14mm = surgery indicated - even if asymptomatic
Flexion-extension views essential - demonstrate dynamic instability
MRI shows pannus and cord - T2 signal change is poor prognostic sign
Awake fibreoptic intubation - safest for AAI
Continue methotrexate, stop biologics - medication management
Ranawat IIIA is optimal timing - don't wait until non-ambulatory

Common Examiner Follow-ups

Q: "What is pannus and why is it important?"

Aspect	Description
Definition	Inflammatory synovial tissue proliferation
Location	Forms behind the dens, around the odontoid
Effect	Compresses cord, erodes bone, causes instability
Treatment response	May reduce with DMARDs/biologics
Surgical relevance	May need to excise if causing compression even after fusion

Pannus can persist even after successful fusion and may need anterior resection if compression continues.

Q: "Why is pre-operative assessment important before other joint surgery in RA patients?"

Concern	Action
AAI may be asymptomatic	Cervical X-rays before any GA
Intubation risk	Avoid neck manipulation
Positioning risk	Lateral for hip surgery stresses neck
Recommendation	Flexion-extension views pre-op if longstanding RA

Patients with ADI >5mm or PADI <14mm need awake fibreoptic intubation and may need cervical stabilisation before elective surgery.

Q: "What is the difference between Harms-Goel and Magerl techniques?"

Aspect	Harms-Goel	Magerl
Screws	Separate C1 lateral mass + C2 pedicle	Transarticular C1-C2
Trajectory	C2 → C1 (two screws per side)	C2 → C1 single screw per side
Reducibility	Can reduce then fix	Must reduce before placing
VA risk	Lower	Higher (screw crosses VA territory)
Current preference	Most common	Less used now

Harms-Goel is preferred because it allows reduction after screw placement and has lower VA injury risk.

Rheumatoid Arthritis - General
Atlantoaxial Instability
Cervical Myelopathy
Occipitocervical Fusion
Basilar Invagination
Upper Cervical Spine Trauma

Rheumatoid Arthritis - Cervical Spine