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ESSENTIALS OF DIAGNOSIS

  • Chronic low backache and stiffness in young adults, worst in the morning.

  • Progressive limitation of back motion and chest expansion.

  • Transient (50%) or persistent (25%) peripheral arthritis.

  • Anterior uveitis in 20–25%.

  • Diagnostic radiographic changes in sacroiliac joints.

  • Negative serologic tests for rheumatoid factor and anti-CCP antibodies.

  • HLA-B27 testing is most helpful when there is an intermediate probability of disease.

GENERAL CONSIDERATIONS

Ankylosing spondylitis is a chronic inflammatory disease of the joints of the axial skeleton, manifested clinically by pain and progressive stiffening of the spine. The age at onset is usually in the late teens or early 20s. The incidence is greater in males than in females, and symptoms are more prominent in men, with ascending involvement of the spine more likely to occur.

CLINICAL FINDINGS

A. Symptoms and Signs

The onset is usually gradual, with intermittent bouts of back pain that may radiate into the buttocks. The back pain is worse in the morning and associated with stiffness that lasts hours. The pain and stiffness improve with activity, in contrast to back pain due to mechanical causes, which improves with rest and worsens with activity. As the disease advances, symptoms progress in a cephalad direction, and back motion becomes limited, with the normal lumbar curve flattened and the thoracic curvature exaggerated. Chest expansion is often limited as a consequence of costovertebral joint involvement. In advanced cases, the entire spine becomes fused, allowing no motion in any direction. Transient acute arthritis of the peripheral joints occurs in about 50% of cases, and permanent changes in the peripheral joints—most commonly the hips, shoulders, and knees—are seen in about 25%. Enthesopathy, a hallmark of the spondyloarthropathies, can manifest as swelling of the Achilles tendon at its insertion, plantar fasciitis (producing heel pain), or dactylitis, which is “sausage” swelling of a finger or toe.

Anterior uveitis is associated in as many as 25% of cases and may be a presenting feature. Spondylitic heart disease, characterized chiefly by atrioventricular conduction defects and aortic regurgitation, occurs in 3–5% of patients with longstanding severe disease. (eFigure 20–20). Pulmonary fibrosis of the upper lobes, with progression to cavitation and bronchiectasis mimicking tuberculosis, may rarely occur, characteristically long after the onset of skeletal symptoms. Radicular symptoms due to cauda equina fibrosis may develop years after onset of the disease.

eFigure 20–20.

Acute iridocyclitis in a patient with ankylosing spondylitis. Note fibrin clot in anterior chamber. (Reproduced, with permission, from Vaughan DG, Asbury T, Riordan-Eva P [editors]. General Ophthalmology, 15th ed. Originally published by Appleton & Lange. Copyright © 1999 by The McGraw-Hill Companies, Inc.)

B. Laboratory Findings

The ESR is elevated in 85% of cases, but serologic tests for rheumatoid factor and anti-CCP antibodies are negative. Anemia ...

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