Juvenile Rheumatoid Arthritis

Published on 21/03/2015 by admin

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Last modified 21/03/2015

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Chapter 46 Juvenile Rheumatoid Arthritis

PATHOPHYSIOLOGY

Juvenile rheumatoid arthritis (JRA) is a chronic autoimmune disease that begins before 16 years of age. It is the most common rheumatic disease in children and is a leading cause of short- and long-term disability. It is also a major cause of eye disease leading to blindness. Although its exact etiology is unknown, it is immune-mediated, with abnormal cytokine production in the inflammatory pathway (increased tumor necrosis factor, interleukin-1 and interleukin-6). There are also genetic predispositions, as well as environmental triggers such as infection, trauma, or stress. JRA causes chronic inflammation of the synovium with joint effusion, which can result in eventual erosion and destruction of the articular cartilage. If the process persists long enough, adhesions between the joint surfaces and ankylosis of the joints develop.

The diagnosis is based on the following criteria defined by the American College of Rheumatology:

Common characteristics of JRA include morning stiffness, joint pain, limping gait, fatigue, anorexia, anemia, and weight loss.

CLINICAL MANIFESTATIONS

COMPLICATIONS

1. Uveitis is intraocular inflammation of the iris and the ciliary body, found in 15% to 20% of children with pauciarticular-onset JRA, in 5% of those with polyarticular-onset JRA, and rarely in children with systemic-onset JRA. At increased risk for development of uveitis are girls with pauciarticular-onset disease. Those with a positive antinuclear antibody are at even higher risk. The onset is usually insidious and asymptomatic; however, approximately half of children have some symptoms (pain, redness, headache, photophobia, change in vision) later in the disease course. If not diagnosed early, the disease can result in cataracts, glaucoma, visual loss, and blindness. If the disease is detected early, the prognosis is improved. In about half of all patients with uveitis, it occurs before the arthritis is diagnosed, at the time of diagnosis or soon after. In 70% to 80% of children, the uveitis is bilateral.

2. Flexion contractures

3. Growth disturbances, including leg length discrepancy and micrognathia

4. Valgus deformity, cervical spine ankylosis

5. Wrist fusion

6. Cardiopulmonary complications and other systemic complications

7. Severe anemia and malnutrition

8. Renal, bone marrow, gastrointestinal, and liver toxicity to drugs

9. Macrophage activation syndrome is a rare but severe complication of systemic JRA leading to severe morbidity and sometimes death. The syndrome is characterized by rapid development of fever, hepatosplenomegaly, lymphadenopathy, and liver failure with encephalopathy, purpura, bruising, and mucosal bleeding. A bone marrow aspiration showing active phagocytosis of red cells and white cells by macrophages and histiocytes confirms the diagnosis.

10. Osteopenia and osteoporosis

LABORATORY AND DIAGNOSTIC TESTS

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