Juvenile idiopathic arthritis is persistent or recurring inflammation of the joints similar to rheumatoid arthritis (see Joint Disorders: Rheumatoid Arthritis (RA)) but beginning at or before age 16.

• Juvenile idiopathic arthritis may cause fever, rash, and lymph node swelling and may affect the heart.
• Diagnosis is based on the child's symptoms and a physical examination because there is no single definitive laboratory test to diagnose the disease.
• Children receive drugs to treat pain and inflammation.
• Flexibility exercises help enhance joint movement.

Juvenile idiopathic arthritis is an uncommon disease characterized by inflammation of joints or connective tissue. The cause is unknown. Although juvenile idiopathic arthritis is not considered a hereditary disorder, hereditary factors may increase a child's chance of developing it.

Symptoms

There are several types of juvenile idiopathic arthritis, each with different characteristics. The type is determined by which symptoms develop during the first 6 months of the disease and how many joints are affected.

In pauciarticular juvenile idiopathic arthritis, four or fewer joints, usually those of the leg (and often the jaw), are affected by pain and swelling. The knee is the most common joint affected. The hip and shoulder are usually spared. Occasionally, a single toe, a finger, or a wrist becomes stiff and swollen.

In polyarthritis, five or more (sometimes as many as 20 to 40) joints are affected. The inflammation usually affects the same joint on both sides of the body—for example, both knees or both hips. The jaw, neck joints, and wrists may be affected. Symptoms may develop slowly. Inflammation may develop in the tendons and connective tissues around joints (tenosynovitis), causing pain, swelling, and warmth. Rarely, generally in adolescents, small lumps (rheumatoid nodules) may form over the elbows, fingers, or toes.

In systemic disease (Still's disease), inflammation occurs at sites other than the joints (which also may be affected). Children with systemic disease typically develop a high fever and rash that frequently appear before joint pain and swelling. The fever comes and goes, usually for at least 2 weeks. The temperature is usually highest in the afternoon or evening (often 103° F [39° C] or higher) and then returns rapidly to normal. A child with fever may feel tired and irritable. The rash is made up of flat, pink-colored or salmon-colored patches—mainly on the trunk and the upper part of the legs or arms. It appears for hours at a time (often in the evening with the fever) and does not always appear in the same spot. The liver, spleen, and lymph nodes may enlarge. Sometimes inflammation develops in the membranes surrounding the heart (pericarditis) or the lungs (pleuritis), causing chest pain. This inflammation may cause fluid to accumulate around the heart or lungs.

With any type of juvenile idiopathic arthritis, the joints may be stiff when the child awakens. Joints often become swollen and warm. Later, joints may become painful, but the pain may be milder than expected from the amount of swelling. Pain may become worse when the joint is moved. A child may be reluctant to walk or may limp. Joint pain persists for years if untreated.

Complications: Any type of juvenile idiopathic arthritis can interfere with physical growth. Joint deformities may develop if untreated. When juvenile idiopathic arthritis interferes with growth of the jaw, a small chin (micrognathia) can result. Long-standing (chronic) joint inflammation can eventually cause deformities or permanent damage of the affected joint.

Inflammation of the iris in the eye (iridocyclitis) can develop with any type of juvenile idiopathic arthritis, but most often iridocyclitis develops with pauciarticular juvenile idiopathic arthritis or polyarthritis. Iridocyclitis in juvenile idiopathic arthritis is asymptomatic (there is no pain or redness), but it can lead to permanent loss of vision if untreated.

Diagnosis

A doctor diagnoses juvenile idiopathic arthritis based on the child's symptoms and the results of a physical examination. There is no single, definitive laboratory test for juvenile idiopathic arthritis, but some blood tests are helpful. The erythrocyte sedimentation rate is usually very abnormal in the systemic form, less so in the polyarticular form, and usually normal in the pauciarticular form. Blood is tested for rheumatoid factor and antinuclear antibodies, which are present in some people with rheumatoid arthritis and related diseases (for example, autoimmune diseases, such as lupus, polymyositis, or scleroderma). However, many children with juvenile idiopathic arthritis do not have rheumatoid factor or antinuclear antibodies in their blood. An adolescent with polyarticular juvenile arthritis and a positive test result for rheumatoid factor has a form of arthritis that is very similar to rheumatoid arthritis in adults.

Children with juvenile idiopathic arthritis who have antinuclear antibodies in their blood are at a higher risk of developing iridocyclitis. X-rays eventually may show characteristic changes in the bones or joints. Children must be examined several times a year by an ophthalmologist for iridocyclitis regardless of whether symptoms are present. If children have systemic juvenile idiopathic arthritis, then an annual eye examination suffices.

Prognosis and Treatment

Symptoms of juvenile idiopathic arthritis may disappear over several years. At least half of children with pauciarticular juvenile idiopathic arthritis and slightly less than half of children with polyarthritis or systemic disease have a complete remission. With early treatment, most children function normally.

The types of juvenile idiopathic arthritis are treated similarly, and the drugs used to reduce pain and inflammation are the same as for rheumatoid arthritis (see Joint Disorders: Treatment). Typically, nonsteroidal anti-inflammatory drugs (NSAIDs—see Pain: Nonsteroidal Anti-Inflammatory Drugs) are used, but children with severe systemic disease may require corticosteroids (such as prednisone) given by mouth or by vein. When corticosteroids are necessary, the lowest possible dose is used to decrease the chance of long-term complications such as slowed growth, osteoporosis, and osteonecrosis (death of bone tissue). If just a few joints are inflamed, doctors may inject corticosteroids directly into the joint.

Sometimes, stronger drugs, such as methotrexateSome Trade Names
TREXALL
, are used for pauciarticular juvenile idiopathic arthritis and are usually needed to treat polyarticular and systemic juvenile idiopathic arthritis. Side effects include bone marrow depression and liver toxicity, so children taking these drugs require regular blood tests. EtanerceptSome Trade Names
ENBREL
and infliximabSome Trade Names
REMICADE
, drugs that block tumor necrosis factor (a protein involved in inflammation), are effective and have improved the outcome for children with juvenile idiopathic arthritis significantly. Systemic juvenile arthritis is often treated with anakinraSome Trade Names
KINERET
, a drug that blocks the inflammatory protein interleukin 1.

Iridocyclitis is treated with corticosteroid eye drops or ointments, which suppress inflammation. If this treatment is not enough, methotrexateSome Trade Names
TREXALL
is frequently used. Eye drops that widen (dilate) the pupil also help prevent permanent eye damage. Eye surgery may be needed if the eye has been damaged.

As in rheumatoid arthritis in adults, nondrug therapies are used for children. For example, physical therapy, splinting, and flexibility exercises help maintain strength and joint function.

Last full review/revision May 2007 by Frank Pessler, MD, PhD; David D. Sherry, MD