Juvenile Rheumatoid Arthritis (JRA)

JRA is the most common form of arthritis in children. It may be a mild condition that causes few problems over time, but it can be much more persistent and cause joint and tissue damage in other children. JRA can produce serious complications in more severe cases.

Affecting children under age 16, juvenile rheumatoid arthritis (JRA), also known as juvenile chronic arthritis, is an immune-mediated 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. Considered the major chronic rheumatic disorder of childhood, JRA affects an estimated 150,000 to 250,000 children in the United States: the overall incidence is twice as high in girls, with variation among the types.

Causes

Signs and symptoms

Signs and symptoms vary with the type of JRA

Systemic JRA

Affecting boys and girls almost equally, systemic JRA accounts for approximately 20% to 30% of cases. The affected children may have mild, transient arthritis or frank polyarthritis associated with fever and rash.

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Joint involvement may not be evident at first, but the child's behavior may clearly suggest joint pain. Such a child may want to constantly 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 often appears, consisting of small, pale or salmon pink macules, most commonly on the trunk and proximal extremities and occasionally on the face, palms, and soles.

Massaging or applying heat intensifies this rash, which is usually most conspicuous where the skin has been rubbed or subjected to pressure, such as that from underclothing.

Other signs and symptoms of systemic JRA may include hepatosplenomegaly, lymphadenopathy, pleuritis, pericarditis, myocarditis, and nonspecific abdominal pain.

Polyarticular JRA

This form of the disorder affects girls four to nine times more often than boys and 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 and those of the 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 RA

Pauciarticular JRA

Involving few joints (usually no more than four), pauciarticular JRA most often affects the knees and other large joints. It accounts for 45% of cases. Three major subtypes exist:

• Pauciarticular JRA with chronic iridocyclitis most commonly strikes girls under age 6 and involves the knees, elbows, ankles, or iris. Inflammation of the iris and ciliary body is often asymptomatic but may produce pain, redness, blurred vision, and photophobia. Young girls who test positive for antinuclear antibody (ANA) are at highest risk for eye complications.
• Pauciarticular JRA with sacroiliitis usually strikes boys (9: 1) over age 8, who tend to be HLA-B27-positive. This subtype is characterized by lower extremity arthritis that produces hip, sacroiliac, heel, and foot pain and Achilles tendinitis. These patients may later develop the sacroiliac and lumbar arthritis characteristic of ankylosing spondylitis. Some also experience acute iritis, but not as frequently as those with the first subtype.
• The third subtype includes patients with joint involvement who test negative for ANA and HLA-B27 and who don't develop iritis. Characterized by asymmetrical involvement of large or small joints, this subtype can strike at any age during childhood. These patients have a better prognosis than those with the first or second subtype, although some may progress to polyarticular disease.
• Common to all types of JRA is joint stiffness in the morning or after periods of inactivity. Growth disturbances may also occur, resulting in overgrowth or undergrowth adjacent to inflamed joints.

Diagnosis

If your child's pediatrician or family doctor suspects that your child has juvenile rheumatoid arthritis, he or she will refer you to a doctor who specializes in arthritis (rheumatologist) to confirm the diagnosis and for treatment.

The diagnosis of juvenile rheumatoid arthritis usually begins with a medical history and a physical examination. Diagnostic tests may include:

• Blood tests. These may include an erythrocyte sedimentation (sed) rate test. Sedimentation rate is the speed at which your red blood cells settle to the bottom of a tube. An elevated rate can indicate inflammation. Measuring the sed rate may be used to rule out other conditions, to help classify the type of juvenile rheumatoid arthritis and to determine the degree of inflammation. Another blood test looks for antibodies in your child's blood. Whether your child has anti-nuclear antibody and rheumatoid factor in his or her blood can help the doctor to determine the type of arthritis. Anti-nuclear antibodies are proteins commonly produced by the immune systems of people with certain autoimmune diseases, including arthritis. Rheumatoid factor is an antibody commonly found in the blood of people with rheumatoid arthritis. In many children with JRA, no significant abnormality will be found in these blood tests.
• Imaging. X-rays may be taken to exclude other conditions, such as fractures, tumors, infection and congenital defects. X-rays may also be used from time to time after the diagnosis to monitor bone development and to detect joint damage.
• Joint fluid removal. The doctor may remove some fluid from your child's swollen joint. This can relieve pain and can help the doctor to identify the cause of the arthritis.

Treatment

Successful management of JRA usually involves administration of anti-inflammatory drugs, physical therapy, carefully planned nutrition and exercise, and regular eye examinations. Both the child and his parents must be involved in therapy.

Aspirin is the initial drug of choice, with the dosage based on the child's weight. However, other nonsteroidal anti-inflammatory drugs (NSAIDs) may also be used. If these prove ineffective, methotrexate has been shown to be a useful second-line agent. In addition, gold salts, hydroxychloroquine, penicillamine, and sulfasalazine may be considered. Responses to the agents may differ among the various subtypes of JRA. Because of adverse effects, systemic steroids are generally reserved for treatment of systemic complications that are resistant to NSAIDs, such as pericarditis and iritis. However, intra-articular steroids can be very effective in managing pauci- and polyarticular JRA.

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Joint rest (by splinting) used for up to three days after joint injections with corticosteroids may improve anti-inflammatory response.

Corticosteroids and mydriatic drugs are commonly used for iridocyclitis. Low-dose cytotoxic drug therapy is currently being investigated.

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.

Generally, the prognosis for JRA is good, although disabilities can occur. 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.

Prevention

Researchers have not yet determined children with JA may also have a marker called C-reactive protein in their blood.  Follow your doctor's recommended treatment plan to reduce the pain of flare-ups and prevent joint deformity.

At home and at school, your child should maintain regular exercise and physical fitness programs. Safe activities include walking, swimming, and bicycling (especially on indoor stationary bikes). Always be certain your child warms up the muscles through stretching before exercising. Making exercise a family activity can increase the level of fun and enthusiasm.