Ankylosing Spondylitis

– A systemic inflammatory disorder affecting primarily the spinal column and the large peripheral joints and eventually resulting in hardening and deformity of the affected skeleton.

Causes and Incidence

Studies support a genetic basis with environmental links, but the exact cause is unknown. A higher than expected level of HLA-B27 tissue antigen is seen in 90% of individuals with the disease. It is three to four times more common in men than in women, and onset typically occurs between 20 and 40 years of age.

Disease Process

The disease most commonly begins in the sacroiliac area of the spine. The intervertebral discs become inflamed and cartilage and bone deteriorate, leading to the formation of fibrous tissue, which infiltrates the disc space and then ossifies. This inflammation and ossification process gradually progresses up the lumbar, thoracic, and cervical spine, leaving behind bamboolike vertebral calcifications.

Symptoms

Early
Recurrent pain in the lower back or large peripheral joints; morning stiffness that is relieved by activity; stooped posture; limited motion of lumbar spine or limited range of motion in affected joints; fatigue; fever; anorexia; weight loss; diminished chest expansion; red, painful eyes.

Late
Kyphosis, fixed flexion of hips, vertebral fractures, impotence, incontinence, diminished bladder and rectal sensation, angina, pericarditis, pulmonary fibrosis (rare).

Potential Complications

Occasionally the disease is severe and rapidly progressive, resulting in severe, pronounced skeletal deformities that greatly inhibit performance of activities of daily living. In rare cases atlantoaxial subluxation occurs, resulting in compression of the spinal cord. Development of secondary amyloidosis, a rare event, can cause death.

Diagnostic Tests

Clinical evaluation
Spine/joint pain or limitation; any manifestations described above; family history.

Radiology
Narrowing in sacroiliac joints, vertebral squaring, calcification, demineralization.

HLA-B27 antigen
Positive in 90% of cases.

Erythrocyte sedimentation rate
Mildly elevated.

IgM rheumatoid factor
Negative.

Treatments

Surgery
Rare; done to correct kyphosis or hip flexion, or for cervical fusion to keep neck upright.

Drugs
Analgesics, nonsteroidal antiinflammatory drugs to reduce pain, spasm, and swelling and to facilitate exercise.

General
Physical therapy, exercise, postural training; traction/back brace in special cases.

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