Ankylosing Spondylitis Lecture Notes

What is Ankylosing Spondylitis?

• Definition: A chronic seronegative inflammatory spondyloarthropathy.
  • Ankylosing: Stiffening or fusion.
  • Spondylitis: Inflammation of the spine.
• Characteristics:
  • Chronic and long-lasting.
  • Seronegative: Negative rheumatoid factor.
  • Inflammatory condition involving joints.

Epidemiology

• More common in men (3:1 ratio).
• Typically onset in early adulthood (15-45 years).
• Strongly associated with HLA-B27 antigen (~80-90% of cases).
• Rule of Two’s:
  • 0.2% of the general population affected.
  • 2% of HLA-B27 positive individuals develop AS.
  • 20% of HLA-B27 positive individuals with a family history develop AS.

Pathogenesis

• Combination of genetic (HLA-B27) and non-genetic factors.
• Alterations in gut microbiome.
• Activation of innate lymphoid cells producing IL-17 and IL-22.
• Inflammatory response involving TNF alpha and COX enzyme.
• Mechanical stress exacerbates inflammation.

Clinical Features

• Axial Skeleton:

  • Mid-lower back pain.
  • Prolonged morning stiffness (>1 hour).
  • Pain improves with activity.
  • Night pain.
  • Decreased spinal mobility.
  • Sacroiliac joint pain (sacroiliitis).

• Peripheral Features:

  • Arthritis in ankles, hips, knees.
  • Enthesitis: Heel pain (Achilles tendon).
  • Dactylitis: Inflammation of toes.

• Complications:

  • Kyphosis: Increased thoracic curve.
  • Spinal stenosis.
  • Secondary osteoporosis.
  • Acute anterior uveitis.
  • Scleritis.
  • Aortic regurgitation.
  • Apical interstitial lung disease.
  • IgA nephropathy.
  • Inflammatory bowel disease.
  • Psoriasis.

Radiological Features

• X-ray Findings:
  • Pseudo-widening of SI joints.
  • Squaring of vertebra edges, shiny corners.
  • Bamboo spine: Fused vertebrae.

Diagnosis

• Clinical Tests:
  • FABER (Patrick's) test.
  • Modified Schober test.
• Criteria:
  • Lower back pain >3 months, onset <45 years.
  • HLA-B27 positive.
  • Radiological findings or clinical symptoms.
• Differentiation:
  • Classic AS with radiological findings.
  • Non-radiographic axial spondyloarthritis without radiological findings.

Treatment

• Conservative Measures:
  • Physiotherapy.
  • Exercise (e.g., swimming).
  • Breathing exercises.
  • Quit smoking.
• Pharmacological Treatments:
  • NSAIDs (e.g., Naproxen, Celecoxib).
  • Proton pump inhibitors for GI protection.
  • Demards for peripheral arthritis (e.g., Methotrexate).
  • Biologics for non-responders (e.g., Adalimumab, Tofacitinib).

Conclusion

• Ankylosing spondylitis is a systemic inflammatory condition with diverse manifestations and complications.
• Early diagnosis and treatment are crucial to managing symptoms and preventing progression.

For more information on rheumatological conditions, refer to additional resources on Rheumatology.