Affecting children younger than age 16, juvenile rheumatoid arthritis (JRA) is an inflammatory disorder of the connective tissues, characterized by joint swelling and pain or tenderness. It may also involve organs such as the skin, heart, lungs, liver, spleen, and eyes, producing extra-articular signs and symptoms.
JRA has three major types: systemic (Still’s disease or acute febrile type), polyarticular, and pauciarticular. Depending on the type, this disease can occur as early as age 6 weeks — although rarely before 6 months — with peaks of onset between ages 1 and 3, and 8 and 12.
The prognosis for JRA is generally good, although disabilities can occur. Long periods of spontaneous remission are common. Improvement or remission may occur at puberty.
The cause of JRA remains puzzling. Research continues to test several theories, such as those linking the disease to genetic factors or to an abnormal immune response. Viral or bacterial (particularly streptococcal) infection, trauma, and emotional stress may be precipitating factors, but their relationship to JRA remains unclear.
Considered the major chronic rheumatic disorder of childhood, JRA affects an estimated 150,000 to 250,000 children in the United States; overall incidence is twice as high in females, with variation among the types of JRA.
Signs and symptoms vary with the type of JRA. Affecting males and females almost equally, systemic JRA accounts for approximately 10% to 30% of cases. The affected children may have mild, transient arthritis or frank polyarthritis associated with fever and rash. Joint involvement may not be evident at first, but the child’s behavior may clearly suggest joint pain. Such a child may constantly want to sit in a flexed position, may not walk much, or may refuse to walk at all. Young children with JRA are noticeably irritable and listless.
Fever in systemic JRA occurs suddenly and spikes to 103° F (39.4° C) or higher once or twice daily, usually in the late afternoon, then rapidly returns to normal or subnormal. (This “sawtooth” or intermittent spiking fever pattern helps differentiate JRA from other inflammatory disorders.) When fever spikes, an evanescent rheumatoid rash commonly appears, consisting of small pale or salmon pink macules, usually on the trunk and proximal extremities and occasionally on the face, palms, and soles. Massaging or applying heat intensifies this rash. It’s usually most conspicuous where the skin has been rubbed or subjected to pressure such as the areas of skin covered by underclothing.
Other signs and symptoms of systemic JRA may include hepatosplenomegaly, lymphadenopathy, pleuritis, pericarditis, myocarditis, and nonspecific abdominal pain.
Polyarticular JRA accounts for about 40% of cases and is three times more common in females than in males; affected children may be seronegative or seropositive for rheumatoid factor (RF). It involves five or more joints and usually develops insidiously. Most commonly involved joints are the wrists, elbows, knees, ankles, and small joints of the hands and feet. Polyarticular JRA can also affect larger joints, including the temporomandibular joints, cervical spine, hips, and shoulders. These joints become swollen, tender, and stiff. Usually, the arthritis is symmetrical; it may be remittent or indolent. The patient may run a low-grade fever with daily peaks. Listlessness and weight loss can occur, possibly with lymphadenopathy and hepatosplenomegaly. Other signs of polyarticular JRA include subcutaneous nodules on the elbows or heels and noticeable developmental retardation.
Seropositive polyarticular JRA, the more severe type, usually occurs late in childhood and can cause destructive arthritis that mimics adult rheumatoid arthritis.
Pauciarticular JRA involves few joints (usually no more than four), typically affecting the knees and other large joints. This form accounts for 45% of cases and has major subtypes. The first, pauciarticular JRA with chronic iridocyclitis, most commonly strikes females younger than age 6 and involves the knees, elbows, ankles, or iris. Inflammation of the iris and ciliary body is commonly asymptomatic but may produce pain, redness, blurred vision, and photophobia.
The second subtype, pauciarticular JRA with sacroiliitis, usually strikes males (9:1) older than age 8, who tend to test positive for human leukocyte antigen (HLA)-B27. This subtype is characterized by lower extremity arthritis that produces hip, sacroiliac, heel, and foot pain as well as Achilles' tendinitis. These patients may later develop the sacroiliac and lumbar arthritis characteristic of ankylosing spondylitis. Some also experience acute iritis, but not as many as those with the first subtype.
The third subtype includes patients with joint involvement who are antinuclear antibody (ANA) and HLA-B27 negative and don’t develop iritis. These patients have a better prognosis than those with the first or second subtype.
Common to all types of JRA is joint stiffness in the morning or after periods of inactivity. Back pain and limited range of motion is common. Growth disturbances may also occur, resulting in uneven length of arms or legs due to overgrowth or undergrowth adjacent to inflamed joints.
Persistent joint pain and the rash and fever clearly point to JRA. Laboratory tests are useful for ruling out other inflammatory or even malignant diseases that can mimic JRA. Disease activity and response to therapy can also be monitored through laboratory results.
❑ Complete blood count shows decreased hemoglobin levels, neutrophilia, and thrombocytosis.
❑ Erythrocyte sedimentation rate and C-reactive protein, haptoglobin, immunoglobulin, and C3 complement levels may be elevated.
❑ ANA test may be positive in patients who have pauciarticular JRA with chronic iridocyclitis.
❑ RF is present in 15% of JRA cases, compared with 85% of rheumatoid arthritis cases.
❑ Positive HLA-B27 antigens may forecast later development of ankylosing spondylitis.
❑ X-rays in early stages reveal changes, including soft-tissue swelling, effusion, and periostitis in affected joints. Later, osteoporosis and accelerated bone growth may appear, followed by subchondral erosions, joint space narrowing, bone destruction, and fusion.
Successful management of JRA usually involves administration of anti-inflammatory drugs, physical therapy, carefully planned nutrition and exercise, and regular eye examinations. Both child and parents must be involved in therapy.
Aspirin is the initial drug of choice, with dosage based on the child’s weight. However, other nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used. If these prove ineffective, gold salts, hydroxychloroquine, and penicillamine may be tried. Because of adverse effects, steroids are generally reserved for treatment of systemic complications, such as pericarditis or iritis, that are resistant to NSAIDs. Corticosteroids and mydriatic drugs are commonly used for iridocyclitis. Low-dose cytotoxic drug therapy is currently being investigated. (See Drug therapy for arthritis, pages 367 and 368.)
Physical therapy promotes regular exercise to maintain joint mobility and muscle strength, thereby preventing contractures, deformity, and disability. Good posture, gait training, and joint protection are also beneficial. Splints help reduce pain, prevent contractures, and maintain correct joint alignment.
Surgery is usually limited to soft-tissue releases to improve joint mobility. Joint replacement is delayed until the child has matured physically and can handle vigorous rehabilitation. (See When arthritis requires surgery, page 369.)
❑ Parents and health care professionals should encourage the child to be as independent as possible and to develop a positive attitude toward school, social development, and vocational planning.
❑ Regular slit-lamp examinations help ensure early diagnosis and treatment of iridocyclitis. Children with pauciarticular JRA with chronic iridocyclitis should be checked every 3 months during periods of active disease and every 6 months during remissions.
Read excerpts from these other book chapters related to Mild arthritis symptoms:
Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
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Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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