What is juvenile idiopathic arthritis?

Juvenile idiopathic arthritis (JIA) is the most common type of arthritis that affects children. It used to be known as juvenile rheumatoid arthritis, but the name was recently changed to reflect the differences between childhood arthritis and adult forms of rheumatoid arthritis.

JIA is a chronic (long-lasting) disease that can affect joints in any part of the body. In this disease, the immune system mistakenly targets the synovium, the tissue that lines the inside of the joint. The synovium responds by making excess fluid (synovial fluid), which leads to swelling, pain and stiffness. The synovium and inflammation process can spread to the surrounding tissues, eventually damaging cartilage and bone. Other areas of the body, especially the eyes, also may be affected by the inflammation. Without treatment, JIA can interfere with a child's normal growth and development.

There are several main subtypes of JIA, which are based on symptoms and the number of joints involved.

• Systemic arthritis - Also called Still's disease, this type occurs in about 10 to 20 percent of children with JIA. A systemic illness is one that can affect the entire person or many body systems. Systemic JIA usually causes a high fever and a rash, which most often appears on the trunk, arms and legs. It also can affect internal organs, such as the heart, liver, spleen and lymph nodes. This type of JIA affects boys and girls equally and rarely affects the eyes.

• Oligoarthritis - This type of JIA affects fewer than 5 joints in the first 6 months of disease, most often the knee, ankle and wrist joints. It also can cause inflammation of the eye (often the iris, the colored area of the eye), called uveitis, iridocyclitis or iritis. About half of all children with JIA have this type, and it is more common in girls than in boys. Many children will outgrow this type of arthritis by adulthood. In some children it may spread to eventually involve more joints.

• Polyarthritis - This type of JIA affects 5 or more joints in the first 6 months, often the same joints on each side of the body. Polyarthritis can also affect the neck and jaw joints as well as small joints, such as those in the hands and feet. It is more common in girls than in boys.

• Psoriatic arthritis - This type of arthritis affects children who have arthritis with the rash of psoriasis. Children frequently have nail changes that look like pitting. The arthritis can precede the rash by many years or vice versa.

• Enthesitis-related arthritis - This type of arthritis often affects the spine, hips and enthesis (attachment point of tendons to bones) and occurs mainly in boys older than 8 years. The eyes are often affected in this type of arthritis. There is often a family history of arthritis of the back (spondylitis) in male relatives.

What are the symptoms of JIA?

Symptoms vary depending on the type of JIA and may include:

• Morning stiffness

• Pain, swelling and tenderness in the joints

• Limping (younger children may not be able to perform motor activities that they recently learned.)

• Fever

• Rash

• Weight loss

• Fatigue or irritability

• Eye redness, eye pain, and blurred vision

What causes JIA?

The exact cause of JIA is not known. However, researchers are studying several factors that may be involved, alone or in combination, in triggering the inflammatory reaction seen in JIA. These factors include genetics, infection, and environmental factors that influence the immune system. JIA, however, is not a hereditary disease like cystic fibrosis, for example.

How common is JIA?

JIA is the most common type of arthritis in children. It affects about 1 in 1,000 children, or about 300,000 children in the United States.

How is JIA diagnosed?

There are no tests that specifically diagnose JIA. Rather, JIA is a diagnosis of exclusion, which means the doctor works to rule out other causes of arthritis and other diseases as the cause of the symptoms.

In making a diagnosis of JIA, the doctor usually begins with a complete medical history that includes a description of symptoms, and a complete physical examination. Imaging techniques such as X-rays or magnetic resonance imaging (MRI) can sometimes show the condition of the joints. Laboratory tests on blood, urine, and/or joint fluid may be helpful in determining the type of arthritis. These include tests to determine the degree of inflammation, antinuclear antibody (ANA), and rheumatoid factor. These tests also can help rule out other diseases - such as an infection, bone disorder, or cancer - or an injury as the cause of your child's symptoms.

How is JIA treated?

The goals of treatment are to relieve pain, reduce swelling, increase joint mobility and strength, and prevent joint damage and complications. Treatment generally includes medications and exercise.

Medications used to treat JIA include:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) - These medicines provide pain relief and reduce swelling, but do not affect the course or prognosis of JIA. Some are available over the counter and others require a prescription. Examples include ibuprofen and naproxen. These medicines can cause nausea and stomach upset in some people and need to be taken with food.

• Corticosteroids (steroids) - In patients with oligo arthritis or in patients with very painful/ swollen joints with other types of JIA, these medications are very effective when given as an injection (shot) into the affected joint. If a child is younger or if several joints are injected, sedation is often used. In patients with more severe widespread disease, these medications occasionally need to be given by mouth as a pill. These medicines, when given by mouth, are effective, but can have serious side effects-including weakened bones -especially when used for long periods. Doctors generally try to avoid using steroids in children because they can interfere with a child's normal growth.

• Disease-modifying anti-rheumatic drugs (DMARDs) - These medications work by changing, or modifying, the actual disease process in arthritis. The aim of DMARD therapy is to prevent bone and joint destruction by suppressing the immune system's attack on the joints. Methotrexate (Rheumatrex®, Trexall®) is the DMARD most often used to treat JIA. Other medications used include sulfasalazine (Azulfidine®) and leflunomide (Arava®).

• Biological modifying agents - Biological agents are medications that directly target molecules or proteins in the immune system that are responsible for causing the inflammation. They are given by injection or by infusion and are used to treat children with more severe arthritis that is not responsive to other medications. Etanercept (Enbrel®), infliximab (Remicade®), adalimumab (Humira®), abatacept (Orencia®) and anakinra (Kineret®) are examples of this type of medication.

Exercise and physical and occupational therapy can help reduce pain, maintain muscle tone, improve mobility (ability to move) and prevent permanent handicaps. In some cases, splints or braces also may be used to help protect the joints as the child grows. Special accommodations with schools may be needed to adjust for children with limitations from their arthritis. The Americans with Disabilities Act ("504" plan) can help facilitate these issues.

What is the outlook for people with JIA?

JIA affects each child differently. For some, the disease is mild and easy to control, with only one or two joints affected. For others, JIA may involve many joints and the symptoms may be more severe and may last longer. With the help of modern medical, physical, and occupational therapy, it is possible to achieve good control of the arthritis, prevent joint damage, and enable normal or near-normal function for most patients. Early detection and treatment may help to control inflammation, prevent joint damage, and maintain your child's ability to function.

What complications are associated with JIA?

If it is untreated, JIA can lead to:

• Loss of vision or decreased vision due to iridocyclitis/uveitis

• Permanent damage to joints

• Chronic arthritis and disability (loss of function)

• Interference with a child's bones and growth

• Inflammation of the membranes surrounding the heart (pericarditis) or lungs (pleuritis)

Can JIA be prevented?

At this time, there is no known way to prevent JIA.

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