161 ANKYLOSING SPONDYLITIS
Harrison’s Manual of Medicine
Chronic and progressive inflammatory disease of the axial skeleton with sacroiliitis (usually bilateral) as its hallmark. Involvement of limb joints other than hips and shoulders is uncommon. Most frequently presents in young men in second or third decade; strong association with histocompatibility antigen HLA- B27. In Europe, also known as Marie-Strumpell or Bechterew’s disease.
Back pain and stiffness—not relieved by lying down, often present at night forcing pt to leave bed, worse in the morning, improves with activity, insidious onset, duration >3 months (often called symptoms of “inflammatory” back pain).
Peripheral joint pain (especially hip).
Chest pain from involvement of thoracic skeleton and muscular insertions.
Extra/juxtaarticular pain—due to “enthesitis”: inflammation at insertion of tendons and ligaments into bone; frequently affects greater trochanter, iliac crests, ischial tuberosities, tibial tubercles, heels.
Extraarticular findings include acute anterior uveitis in about 20% of pts, aortitis, aortic insufficiency, GI inflammation, cardiac conduction defects, amyloidosis, bilateral upper lobe pulmonary fibrosis.
Constitutional symptoms may occur: fever, fatigue, weight loss.
Neurologic complications related to spinal fracture/dislocation (can occur with even minor trauma), atlantoaxial subluxation, cauda equina syndrome.
Tenderness over involved joints
Diminished chest expansion
Diminished anterior flexion of lumbar spine (Schober test)
ESR and C-reactive protein elevated in majority.
Rheumatoid factor and ANA negative.
HLA-B27 may be helpful in pts with inflammatory back Sx but negative x- rays.
Radiographs: early may be normal. Sacroiliac joints: usually symmetric; bony erosions with “pseudowidening” followed by fibrosis and ankylosis. CT can detect changes earlier than plain x-ray. Spine: squaring of vertebrae; syndesmophytes; ossification of annulus fibrosis and anterior longitudinal ligament causing “bamboo spine.” Sites of enthesitis may ossify and be visible on x-ray.
Modified New York criteria widely used: radiographic evidence of sacroiliitis plus one of: (1) Hx of inflammatory back pain symptoms, (2) lumbar motion limitation, (3) limited chest expansion.
DIFFERENTIAL DIAGNOSIS Spondyloarthropathy associated with reactive arthritis, psoriatic arthritis, enteropathic arthritis (Fig. 161-1). Diffuse idiopathic skeletal hyperostosis.
FIGURE 161-1. Algorithm for diagnosis of the spondyloarthropathies.
Exercise program to maintain posture and mobility is key to management.
NSAIDs (e.g., indomethacin 75 mg slow-release qd or bid) useful in most pts.
Sulfasalazine 2–3 g/d may be useful.
No therapeutic role for systemic glucocorticoids or other immunosuppressive has been documented in ankylosing spondylitis.
Adjunctive therapy includes intraarticular glucocorticoids for persistent enthesitis or peripheral synovitis; ocular glucocorticoids for uveitis; surgery for severely affected or deformed joints.
For a more detailed discussion, see Taurog JD, Lipsky PE: Ankylosing Spondylitis, Reactive Arthritis, and Undifferentiated Spondyloarthropathy, Chap. 315, p. 1949, in HPIM-15.