# 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 **Cervical Spine Involvement in Rheumatoid Arthritis:** RA affects the cervical spine in up to 80% of patients with longstanding disease. Three distinct patterns occur, often in combination. **1. Atlantoaxial Instability (AAI) - Most Common (65%)** | Feature | Details | |---------|---------| | **Pathology** | Pannus formation, transverse ligament laxity/rupture | | **Direction** | Anterior subluxation (most common), posterior, rotatory, lateral | | **Presentation** | Suboccipital headache, C2 neuralgia, neck pain | | **Measurement** | ADI (atlantodental interval) | **ADI Interpretation:** | ADI | Significance | |-----|--------------| | <3mm | Normal | | 3-6mm | Mild instability | | 6-9mm | Moderate instability - transverse ligament incompetent | | >9mm | Severe instability - alar ligaments also affected | **PADI (Posterior Atlantodental Interval):** | PADI | Significance | |------|--------------| | >14mm | Adequate space for cord | | <14mm | **Risk of cord compression** | | <10mm | High risk of paralysis | **This Patient:** ADI 6mm (neutral), 10mm (flexion), PADI 12mm = significant instability with cord at risk. **2. Basilar Invagination (Cranial Settling) - 20-25%** | Feature | Details | |---------|---------| | **Pathology** | Lateral mass erosion, cranial migration of odontoid | | **Result** | Odontoid protrudes into foramen magnum | | **Presentation** | Brainstem symptoms, vertebrobasilar symptoms | | **Measurement** | Various lines (McGregor, Chamberlain, Ranawat) | **Ranawat Criteria (Most Commonly Used):** - Measure distance from C1 arch to C2 pedicle axis - Class I: >15mm (normal) - Class II: 10-15mm (settling) - Class III: <10mm (severe settling) **Alternative - McRae's Line:** - Odontoid tip should not project above foramen magnum line **3. Subaxial Subluxation - 20-25%** | Feature | Details | |---------|---------| | **Pathology** | Facet erosion, disc/ligament destruction | | **Pattern** | "Stepladder" deformity - multiple levels | | **Level** | C3-4, C4-5 most common | | **Presentation** | Myelopathy, radiculopathy | | **Measurement** | >3.5mm subluxation or >11° angulation = unstable | **This Patient:** Has both AAI (ADI 10mm in flexion) AND subaxial subluxation (C3-4, C4-5). > **Consultant Tip:** Always assess for all three patterns in RA patients. Combined AAI + subaxial subluxation is common and requires longer fusion construct. **Clinical Features of Cervical Myelopathy in RA:** Diagnosis is challenging - RA patients have baseline disability from peripheral joint disease. **Upper Motor Neuron Signs:** | Sign | This Patient | |------|--------------| | Hyperreflexia | Yes (3+) | | Hoffman's sign | Positive bilateral | | Ankle clonus | Present (3 beats) | | Babinski (upgoing plantar) | Positive bilateral | | Gait abnormality | Wide-based, unsteady | **Sensory Changes:** | Finding | This Patient | |---------|--------------| | Proprioception loss | Reduced in lower limbs | | Romberg test | Positive | | Vibration sense | Often reduced | **Other Myelopathic Features:** | Feature | Description | |---------|-------------| | Lhermitte's sign | Electric shock with neck flexion | | Hand clumsiness | Difficulty with buttons (hard to assess in RA hands) | | Bladder symptoms | Late feature - urgency, retention | **Ranawat Classification of Myelopathy in RA:** | Class | Description | This Patient | |-------|-------------|--------------| | **I** | No neurological deficit | | | **II** | Subjective weakness, hyperreflexia, dysesthesia | | | **IIIA** | Objective weakness, ambulatory | **Yes - IIIA** | | **IIIB** | Non-ambulatory, quadriplegic | | **This Patient:** Ranawat Class IIIA - objective weakness (4/5), ambulatory but unsteady, UMN signs present. **Sharp-Purser Test:** | Aspect | Description | |--------|-------------| | **Technique** | Patient flexes neck, examiner applies posterior pressure on forehead | | **Positive** | Palpable "clunk" as C1 reduces on C2 | | **Meaning** | AAI present | | **Caution** | Do NOT perform if severe myelopathy or instability known | **Indications That Myelopathy is from Cervical Spine (not RA alone):** | Feature | Suggests Myelopathy | |---------|---------------------| | UMN signs | Not explained by peripheral RA | | Asymmetric presentation | May indicate specific level | | Bladder involvement | Suggests cord compression | | Rapid progression | Cervical pathology | | Suboccipital headache | C1-C2 involvement | > **Consultant Tip:** Ranawat class IIIA is the optimal time for surgery - still ambulatory but clear objective deficit. Class IIIB has poor outcome even with surgery. **Imaging Protocol for RA Cervical Spine:** **1. Plain Radiographs - Essential** | View | Purpose | |------|---------| | AP | Assess alignment, lateral mass integrity | | Lateral (neutral) | ADI, PADI, basilar invagination | | Flexion | Dynamic AAI | | Extension | Dynamic reduction | **Critical Measurements:** **Atlantodental Interval (ADI):** | Measurement | How | |-------------|-----| | **Position** | Measure anterior cortex of dens to posterior cortex of C1 anterior arch | | **Normal** | <3mm in adults, <5mm in children | | **Flexion** | Should not increase significantly | **Posterior Atlantodental Interval (PADI):** | Measurement | Significance | |-------------|--------------| | **Position** | Posterior cortex of dens to anterior cortex of C1 posterior arch | | **Critical value** | <14mm = cord at risk | | **<10mm** | High paralysis risk | **PADI is more predictive of neurological outcome than ADI.** **Basilar Invagination Lines:** | Line | Description | Normal | |------|-------------|--------| | **McGregor** | Hard palate to occiput | Dens tip <4.5mm above | | **Chamberlain** | Hard palate to opisthion | Dens tip at or below | | **McRae** | Foramen magnum | Dens should not project above | | **Ranawat** | C1 arch to C2 pedicle axis | >15mm normal | **Subaxial Subluxation:** - >3.5mm translation = unstable - >11° angulation = unstable **2. MRI - Essential for Myelopathy** | Finding | Significance | |---------|--------------| | **Pannus** | Soft tissue posterior to dens (enhances with Gd) | | **Cord compression** | From pannus, subluxation | | **Cord signal change** | T2 hyperintensity = myelomalacia (poor prognosis) | | **Subaxial stenosis** | May need decompression | **This Patient's MRI:** Pannus at C1-C2, cord compression, T2 signal change = established myelopathy. **3. CT Scan** | Purpose | Details | |---------|---------| | Bone anatomy | Lateral mass morphology for screw placement | | Fracture | Dens erosion vs fracture | | Fusion planning | Occipital bone thickness, vertebral artery position | **4. CT Angiography (if occipitocervical fusion planned)** | Concern | Details | |---------|---------| | Vertebral artery | Anomalous course, dominance | | Planning | Screw trajectory to avoid VA | > **Consultant Tip:** PADI <14mm is the most reliable predictor of neurological risk. Always get flexion-extension views and MRI in symptomatic RA patients. **Indications for Surgery:** **Absolute Indications:** | Indication | Criteria | |------------|----------| | **Myelopathy** | Any neurological deficit from cervical spine | | **PADI <14mm** | Even if asymptomatic - cord at risk | | **ADI >9mm** | Significant instability | | **Cord signal change on MRI** | Established myelopathy | | **Basilar invagination with brainstem symptoms** | Cranial nerve, vertebrobasilar | **Relative Indications:** | Indication | Criteria | |------------|----------| | **ADI >6mm** | Moderate instability | | **Progressive subluxation** | On serial imaging | | **Intractable neck pain** | With instability | | **Planned arthroplasty** | Pre-operative stabilisation if unstable | **This Patient's Surgical Indications:** - Myelopathy (Ranawat IIIA) - ADI 10mm in flexion - PADI 12mm (<14mm) - Cord signal change on MRI **Surgery is clearly indicated.** **Surgical Options:** **Option 1: C1-C2 Fusion (If No Basilar Invagination)** | Technique | Details | |-----------|---------| | **Magerl (Transarticular screws)** | Strongest, but risk to VA | | **Harms-Goel (C1 lateral mass + C2 pedicle screws)** | Most common, adjustable | | **Brooks/Gallie (Wiring)** | Older, less rigid, not recommended alone | **Harms-Goel Technique (Preferred):** | Step | Details | |------|---------| | 1 | Prone, Mayfield clamp | | 2 | Expose C1-C2 (avoid venous plexus at C1-2 junction) | | 3 | C1 lateral mass screws (entry: posterior arch/lateral mass junction) | | 4 | C2 pedicle or pars screws | | 5 | Rod placement | | 6 | Reduction by compression if needed | | 7 | Decorticate, bone graft | **Option 2: Occipitocervical Fusion (If Basilar Invagination)** | Indication | Rationale | |------------|-----------| | Basilar invagination present | C1-C2 alone won't address cranial settling | | C1 lateral mass eroded | Can't place C1 screws | | Severe AAI requiring distraction | Occipital fixation gives better leverage | **Technique:** - Occipital plate with screws in midline keel (thickest bone) - Subaxial lateral mass or pedicle screws - Consider extending to subaxial levels if subluxation present **This Patient's Procedure:** Given: - AAI without significant basilar invagination - Subaxial subluxation at C3-4, C4-5 - Cord compression at both C1-2 and C4-5 **Recommended:** Occipitocervical fusion to upper thoracic spine (O-C to T2) - Reason: Combine AAI stabilisation + address subaxial disease - Prevents adjacent segment failure - Single operation > **Consultant Tip:** If there is combined AAI + subaxial subluxation, extend the fusion to include all involved levels. Stopping short risks adjacent level failure. **Perioperative Considerations in RA:** RA patients have unique surgical challenges requiring multidisciplinary planning. **1. Anaesthetic Considerations:** **Airway Management:** | Issue | Management | |-------|------------| | **Cervical instability** | Awake fibreoptic intubation preferred | | **TMJ involvement** | Limited mouth opening | | **Cricoarytenoid arthritis** | Stridor risk, may need smaller tube | | **Atlantoaxial instability** | Avoid excessive neck manipulation | **Recommended Approach:** - Awake fibreoptic intubation with in-line stabilisation - Continue immobilisation until positioned **2. Positioning:** | Concern | Precaution | |---------|------------| | **Joint deformities** | Careful padding, avoid excessive pressure | | **Osteoporosis** | Gentle positioning, risk of fracture | | **Cervical manipulation** | Mayfield with minimal adjustment | | **Prone positioning** | Consider turning with patient awake to check neurology | **3. Bone Quality:** | Issue | Management | |-------|------------| | **Osteoporosis (steroids)** | May need cement augmentation | | **Erosive disease** | Lateral mass may be eroded | | **Screw fixation** | Consider bicortical purchase | | **Fusion** | Use BMP or iliac crest, may need augmentation | **4. Medications:** | Medication | Perioperative Management | |------------|-------------------------| | **Methotrexate** | Continue (stopping increases flare risk without reducing infection) | | **Biologics (anti-TNF)** | Hold 2 half-lives before surgery | | **Steroids** | Stress-dose hydrocortisone if on chronic steroids | | **NSAIDs** | Stop 5-7 days before (bleeding) | **Biologic Drug Half-lives:** | Drug | Half-life | Stop Before Surgery | |------|-----------|-------------------| | Etanercept | 4 days | 1 week | | Adalimumab | 14 days | 4 weeks | | Infliximab | 8-10 days | 4 weeks | | Rituximab | 21 days | 4-6 weeks | **5. Wound Healing:** | Risk Factor | This Patient | |-------------|--------------| | Chronic steroids | Yes | | Immunosuppression | Methotrexate | | Poor nutrition | Anaemia, low albumin likely | | Diabetes | Check | **Strategies:** - Optimise nutrition pre-op - Minimise soft tissue trauma - Consider drains - Delayed skin closure if concern **6. DVT Prophylaxis:** | Factor | Consideration | |--------|---------------| | Immobilisation | Increased risk | | Obesity | Often low BMI in RA | | Recommendation | Mechanical + chemical (LMWH) once safe | > **Consultant Tip:** Awake fibreoptic intubation is safest for AAI. Continue methotrexate but stop biologics. Always give stress-dose steroids if on chronic steroids. **Expected Outcomes:** **Neurological Outcomes by Ranawat Class:** | Pre-op Class | Expected Outcome | |--------------|------------------| | **I (no deficit)** | Excellent - prevent deterioration | | **II (subjective)** | Good - often improve | | **IIIA (ambulatory)** | Fair - 60-70% improve or stabilise | | **IIIB (non-ambulatory)** | Poor - rarely regain ambulation | **This Patient (Ranawat IIIA):** - 60-70% chance of neurological improvement - 20-30% stabilise (no further decline) - 10% continue to deteriorate despite surgery **Pain Outcomes:** - 80-90% report improvement in neck/occipital pain - Suboccipital headaches typically resolve **Factors Predicting Better Outcome:** | Factor | Better Prognosis | |--------|------------------| | Shorter symptom duration | <6 months | | Ambulatory pre-op | IIIA > IIIB | | No cord signal change | T2 hyperintensity = worse | | Younger age | Better recovery | | Good reduction | Improved alignment | **Complications:** **Intraoperative:** | Complication | Rate | Prevention/Management | |--------------|------|----------------------| | Vertebral artery injury | 2-4% | Pre-op CTA, careful drilling | | Dural tear | 2-5% | Pannus adherent to dura | | Neurological worsening | 2-5% | Neuromonitoring, careful positioning | | Bleeding | Variable | Meticulous haemostasis | **Early Post-operative:** | Complication | Rate | Management | |--------------|------|------------| | Wound infection | 5-10% | Higher in RA, may need washout | | Haematoma | 2-5% | Drain, evacuation if expanding | | Dysphagia | 5-10% | Usually temporary | | Respiratory | Variable | High cervical can affect C3-5 (phrenic) | **Late Complications:** | Complication | Rate | Prevention | |--------------|------|------------| | **Non-union** | 5-15% | Rigid fixation, autograft, optimise nutrition | | **Adjacent segment disease** | 10-20% | Extend fusion if multiple levels involved | | **Hardware failure** | 5-10% | Good bone quality, adequate construct | | **Subaxial subluxation** | 10-15% | May need extension of fusion | **Follow-up Protocol:** | Time | Assessment | |------|------------| | **2 weeks** | Wound check, remove sutures | | **6 weeks** | Clinical exam, X-rays (check alignment) | | **3 months** | Assess neurology, flexion-extension X-rays | | **6 months** | CT to assess fusion | | **12 months** | Final assessment, discharge if fused | | **Then annually** | Monitor for adjacent segment disease | **Collar Use:** - Rigid collar 8-12 weeks typically - May extend if osteoporotic or concern about fixation **Return to Activity:** - Avoid lifting, straining for 3 months - Light activity from 6 weeks - Full activity when fused (6 months) **Counselling Points for This Patient:** 1. Surgery should stabilise/improve your symptoms 2. May not fully recover to normal (cord already damaged) 3. Long recovery - collar for 2-3 months 4. Will lose some neck motion (acceptable trade-off) 5. Risk of complications is higher due to RA and medications 6. Will need lifelong monitoring for adjacent segment problems > **Consultant Tip:** Counsel that surgery is to prevent further deterioration. Complete recovery is unlikely if myelopathy is established (cord signal change). IIIA is the optimal time - don't wait until IIIB. --- ## 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 1. **PADI <14mm = surgery indicated** - even if asymptomatic 2. **Flexion-extension views essential** - demonstrate dynamic instability 3. **MRI shows pannus and cord** - T2 signal change is poor prognostic sign 4. **Awake fibreoptic intubation** - safest for AAI 5. **Continue methotrexate, stop biologics** - medication management 6. **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. --- ## Related Topics - Rheumatoid Arthritis - General - Atlantoaxial Instability - Cervical Myelopathy - Occipitocervical Fusion - Basilar Invagination - Upper Cervical Spine Trauma