Rheumatoid Arthritis Cervical Spine

Posted bythespinebookadminPosted inInflammatory and Systemic, Topics

For background refer to: Rheumatoid Arthritis 

Background 

  • 3 pattens of instability 
    • Atlantoaxial 
    • Basilar invagination (atlantoaxial impaction, cranial settling,) 
    • Subaxial subluxation 
  • Dx with flex ex and MRI 
  • 90% of people with RA, often missed 
    • Pre-biologic agent data – incidence much lower now 
  • Anti CCP is best marker for RA 

Ranawat Class 

  • 1 – Pain, no neuro 
  • 2 – Subjective weakness 
  • 3A – Weakness, long tract, ambulatory 
  • 3B – weakness, long tract, non ambulatory 

Pathophysiology 

  • AA instability  
    • weaken/ rupture of transverse/ alar/ apical ligaments, pannus between odontoid and C1 arch 
    • Synovial joint (odontoid and TAL) – so higher risk 
    • Collapses the joints and then lateral masses 
  • AA impaction  
    • Follows AA instability 
    • lateral masses collapse as OC1 and C12 joints involved 
  • Subaxial –  
    • destabilize facet joints (capsule and interspinous ligaments) 
    • RF 
      • Steroids 
      • Males 
      • Seropositive RA 
      • Severe RA 
      • Nodules present 
  • No synovitis in disk/ annular tissue 

Cervicomedullary Syndrome 

  • Due to: atlantoaxial impaction (basilar invag) 
  • Presentation 
    • Headache 
    • Ataxia 
    • Lower cranial nerve dysfunction 
    • UMN signs 
    • Nystagmus 
    • Dysphagia 
    • OSA 

Radiographic 

  • Indications for flex ex views 
    • Neuro 
    • Scheduled procedures 
    • Functional deterioration 
  • Basilar Invagination 
    • McRae 
      • Basion opisthion 
      • Tip should be below 
    • McGregor’s 
      • Hard palate and base of occiput 
      • Tip max 5mm above 
    • Ranawat 
      • Line across C1 to center of C2 pedicle 
        • <15mm in male <13mm in females is pathologic 
    • Cervicomedullary Angle 
      • <135 means impending neuro 
    • Clark’s station 
      • Odontoid into 1/3rds 
      • Anterior ring of C1 is at 2 or 3rd sttation 
  • Atlantoaxial instability 
    • ADI >3mm (flex ex or static) 
    • PADI <14 
      • Predictor for success 
        • If PADI <10 preop, paralysis does not resolve 
        • If >14mm, best predictor for resolving motor deficit 
  • Subaxial 
    • 20% listhesis 

Management 

  • Indications for surgery 
    • Intractatble pain 
    • Neuro 
    • Basilar 
      • Cervicomedullar <135 
      • Dens >5 McGregor 
    • AA 
      • ADI >10 
      • PADI <14 
    • Subaxial 
      • Canal <14 

Diagnostic Imaging 

  • Atlantoaxial Subluxation (C1-C2) 
    • PADI 
      • Dorsal aspect of odontoid – Ventral surface of lamina of C1 
      • Normal >14mm (97% sensitive for detecting paralysis) 
      • Instability 
        • <14mm – decompression 
        • <10mm – no recovery of spinal cord expected (Boden et al JBJS) 
        • <13mm with basilar invagination – no recovery 
    • ADI 
      • Posterior edge of anterior ring of C1 – anterior edge of odontoid 
      • Normal <3.5mm 
      • 10mm – clinically significant with transverse ligament disruption 
      • Not useful for predicting neurologic sequelae because of natural history of Atlantoaxial subluxation; superior migration happens next which actually decreases the ADI 
  • Basilar Invagination (O-C1) *cardiac arrest 
    • McGregor Line  
      • Base of hard palate – outter table of occiput 
        • Tip of odontoid perpendicular to this line 
        • If tip >4.5mm above this line; superior migration 
    • Clark Method 
      • What level is the C1 anterior arch at relative to C2 
        • Proximal 1/3 dens 
        • Middle 1/3 
        • Distal 1/3 
    • Redlund Johnell (preferred by Dr. Rampersaud) 
      • Draw line up C2 Dens from base of C2 
      • Draw McGregor Line 
      • Distance must be >34mm men; 29mm in women 
    • CT Myelography/MRI 
      • Cervicomedullary Angle 
        • Line along dorsal surface of the odontoid 
        • Line along ventral and parallel to medulla 
        • Normal 135-170 
        • <135-> atlantoaxial impaction &myelopathy 
  • Subaxial 
    • Staircase 
    • Significant slippage – do flex-ex views 
      • >4mm 
      • 20% listhesis 
      • >13mm SAC 

Management 

  • Cervical Instability diagnosed 
    • Early onset and is correlated with appendicular disease activity 
    • High mortality once myelopathy onset 
  • Atlantoaxial Instability 
    • Up to 80% 
    • Pannus separating dens and C1 ring 
    • Erosive synovitis 
  • Basilar impression aka vertical settling aka atlanto axial imapction 
    • Skull settling onto the atlas and atlas onto axis due to erosive arthritis and bone loss 
      • Vertebral artery thrombosis can occur 
      • 38% 
  • Subaxial 
    •  less common and more subtle (10-20%) 
    • Usually multiple 
    • Synovitis of facets and Luschka joints and erosion of endplates 
    • Can have root compression from foraminal narrowing 
  • Non-operative Management 
    • DMARDs early use to prevent irreversible damage 
    • Goals 
      • Prevent neuro injury, avoid sudden death, minimize pain, maximize funsion 
    • Medial management with Rheumatologist 
    • Cervical Orthosis for pain 
    • Isometric exercises to stabilize neck without excessive motion 
    • Yearly follow-up with 5 view XRs 
  • Operative 
    • Indications 
      • Neuro deficit 
      • Instability 
      • Pain 
      • Rationale: 
        • d 
    • Complication 
      • Mortality 5-10% 
      • Wound issues 25% 
    • Reduction 
      • Traction – Halo pre op 
      • Intraoperative – MEPs allow you to reduce intra-operatively 
      • Anterior approach if irreducible midline pannus/ compression 
    • Fusion 
      • Atlanto-Axial Instability (C1-2) 
        • Reducible 
          • Posterior wiring (Gallie or Brooks) 
          • Magerl 
            • Contraindicated with high-riding vertebral artery 
          • Goel Harms 
            • C2 Lateral Mass (C2 pedicle can also be an issue with HRVA) 
            • C1 Pedicle 
        • Non-reducible 
          • Magerl + C1 Laminectomy 
          • Goel Harms + C1 Laminectomy 
      • Basilar Impaction 
        • Reducible with Traction 
          • O-C2 Fusion 
        • Irreducible with Traction 
          • O-C2 Fusion with C1 Laminectomy