JUVENILE ARTHRITIS

DEFINITION

Juvenile arthritis (JA) refers to a number of different conditions with two characteristics in common. First, they all strike children. Second, they all involve inflammation of the joints.

DESCRIPTION

Humans can move their head, arms, legs, fingers, and toes because of joints. A joint is a structure where two or more bones come together. The elbow, for example, is a joint at which bones in the upper and lower arm come together.

The space between the bones in a joint is occupied by a variety of other structures and fluids. These structures and fluids help the bones move more smoothly. One of the structures in a joint is the articular capsule. The articular capsule surrounds the bones that come together at a joint and the space between the joint. The articular capsule contains a thin covering called the synovial (pronounced si-NO-vee-uhl) membrane. The synovial membrane produces a clear liquid called synovial fluid that lubricates the space between the bones. The synovial fluid helps the bones slide across each other more easily.

Juvenile arthritis is joint inflammation that affects children under the age of sixteen and that lasts for at least three to six months. The condition often goes through periods in which joints are very sore and painful and then return to normal. (©

John Moss

. Reproduced by permission of

Photo Researchers, Inc.

)

In juvenile arthritis, the synovial membrane becomes very inflamed. Instead of being thin and flexible, it becomes thick and stiff. This change occurs when white blood cells invade the membrane. The white blood cells release chemicals that cause inflammation and attack other structures in the joint. The bones, ligaments, and other structures in the joint are worn away and the joint can no longer move smoothly and easily. Bending and turning movements cause pain and discomfort.

Juvenile arthritis is a joint inflammation that affects a child under the age of sixteen and that lasts for at least three to six months. The condition often goes through periods in which joints are very sore and painful and then return to normal. After a while the inflammation returns and joints are once again sore and painful.

CAUSES

A number of possible causes for JA have been suggested. Some researchers feel that the disorder may have a genetic basis. It seems to occur more often in some families than in others. Other researchers think the disorder may be caused by an infectious agent, such as a bacterium or a virus, but no such agent has ever been found.

Some evidence suggests that JA may be an autoimmune disorder (see autoimmune disorder entry). An autoimmune disorder is one in which the body's immune system becomes confused. It behaves as if some normal part of a person's body is actually a foreign substance. The immune system then sets out to attack and destroy that part of the body. According to this explanation, a person's immune system mistakenly attacks his or her joints, causing the symptoms of juvenile arthritis.

SYMPTOMS

The most common symptoms of JA include pain, stiffness, redness, swelling, and warmth in a joint. Over time, the bones around an infected joint may grow too quickly or too slowly. As a result, a child's arms and legs may be of different lengths. A common consequence of JA is the condition known as contracture. Contracture is a shortening of muscle that occurs when the muscle is not used. Contracture occurs in JA patients because they find it painful to move, so their muscles are not exercised normally.

Five types of JA have been identified. Each type has its own specific symptoms. These five types are:

• Pauciarticular JA. Pauciarticular (pronounced paw-see-ar-TIK-yoo-luhr) JA is the most common and least severe form of JA and affects about 40 percent to 60 percent of all JA patients. Pauciarticular JA usually occurs in only four joints: the knee, ankle, wrist, and/or elbow. It usually does not interfere with the patient's growth. Less than 15 percent of patients with this form of JA end up with deformed joints. Some children with the disorder have swelling in a joint without pain. Others develop an inflammation of the eye that can lead to blindness if left untreated. Many children with pauciarticular JA recover completely within a few years of diagnosis.
• Polyarticular JA. About 40 percent of all cases of JA are polyarticular (pronounced pol-ee-ar-TIK-yuh-luhr). It occurs more commonly among girls than boys. Polyarticular JA usually develops before the age of three or after the age of ten and affects five or more joints at the same time. It occurs most commonly in the small joints of both hands and both feet, but it can also develop in larger joints, such as the elbow or knee. If the condition occurs in both knees at once, the patient's legs may grow at different rates so that one leg becomes longer than the other.

About half of all patients with polyarticular JA have arthritis of the spine and/or hip. Many patients with the disorder also have more general symptoms, such as anemia (low red blood cell count; see anemias entry), decreased growth rate, poor appetite, low-grade fever, and a slight rash.

This form of JA is most severe when it occurs during early adolescence. In some cases, the disorder may be an early form of an adult disorder known as rheumatoid arthritis (see arthritis entry). The disorder can be very serious because it destroys and deforms the joints.

Systemic onset JA. Systemic onset JA is also called Still's disease after the doctor who first described it. It occurs in 10 percent to 20 percent of patients with JA and is equally common in boys and girls. The disorder is usually first seen between the ages of five and ten. The initial symptoms of systemic onset JA do not occur in the joints. Instead, they are general symptoms, such as high fever, rash, loss of appetite, and weight loss. More serious symptoms may also develop, including pericarditis (inflammation of the sac surrounding the heart; pronounced per-i-kar-DIE-tiss), pleuritis (inflammation of the tissue lining the lungs; pronounced ploor-I-tuhs), and myocarditis (inflammation of the heart muscle; pronounced my-o-kar-DIE-tiss).

Typical symptoms of arthritis affecting the joints usually develop later in systemic onset JA. They generally show up in the wrists and ankles. Many children go through regular cycles when their condition becomes worse and then better. They may also develop polyarticular JA.

Spondyloarthropathy. Spondyloarthropathy (pronounced SPON-duhlo-ar-THROP-uh-thee) is relatively rare. It occurs most commonly in boys older than eight. Arthritis develops first in the knees and ankles and then moves upward to include the hips and lower spine.

Psoriatic JA. Psoriatic (pronounced sore-ee-AT-ik) JA usually starts in fewer than four joints. However, it gradually spreads to include many joints, as in polyarticular JA. The hips, back, fingers, and toes are often affected. A skin condition known as psoriasis (pronounced suh-RIE-uh-sis) accompanies this form of JA. Psoriatic JA often becomes a serious, disabling problem.

DIAGNOSIS

Diagnosis is usually made on the basis of a patient's symptoms. Laboratory tests are often not very helpful because they do not show any indication of disease.

TREATMENT

The goal of treating JA is to decrease the inflammation in a joint. In this way, the patient retains better movement. Common medications used to reduce inflammation are the nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (pronounced i-byoo-PRO-fuhn, trade name Advil) and naproxen (pronounced nuh-PROKS-suhn, trade name Aleve). Steroid drugs can also be given by mouth or injection. Oral injections are helpful but have dangerous long-term side effects. Injections of steroids directly into a joint are often the best treatment.

Other drugs used to treat JA include methotrexate (pronounced methuh-TREK-sate), sulfasalazine (pronounced SULL-fuh-SAL-uh-zeen), penicillamine (pronounced pen-i-SIL-uh-meen), and hydroxychloroquine (pronounced hi-droks-ee-KLOR-uh-kween). Steroid eyedrops can be used to treat eye inflammations.

Physical therapy and exercise are often recommended to improve joint mobility and muscle strength. Occasionally, splints are used to rest painful joints and to prevent or improve deformed joints.

Alternative Treatment

Some practitioners recommend juice therapy for treating JA. Patients are encouraged to drink a mixture of fruit and vegetable juices, including carrots, celery, cabbage, cherries, lemons, beets, cucumbers, radishes, and garlic. Another alternative therapy is aromatherapy, in which the patient inhales vapors that include cypress, fennel, and lemon. Massage with oils such as rosemary, chamomile, camphor, juniper, and lavender can sometimes be helpful. Other types of therapy include acupuncture (a Chinese therapy that involves the use of fine needles) and acupressure (a Chinese therapy treatment during which pressure is applied to certain points in the body).

Some authorities believe that nutritional supplements can relieve the symptoms of JA. These supplements include large amounts of antioxidants (vitamins A, C, and E; zinc; and selenium) as well as B vitamins and minerals such as boron, copper, and manganese.

There is some evidence that JA can be caused by food allergies. Patients should identify any foods that increase their symptoms and exclude those foods from their diet.

PROGNOSIS

The prognosis for pauciarticular JA and spondyloarthropathy is quite good. It is not as good for polyarticular JA, which can sometimes lead to more serious forms of arthritis when the patient gets older, as well as to joint deformities. The prognosis for systemic onset JA depends on the organs affected. About 1 percent to 5 percent of all JA patients die of complications of the disorder, such as infection, inflammation of the heart, or kidney disease.

PREVENTION

Because so little is known about the causes of JA, there are no recommendations for avoiding the disorder.

FOR MORE INFORMATION

Books

Aldape, Virginia Tortorica. Nicole's Story: A Book About a Girl With Juvenile Rheumatoid Arthritis. Minneapolis, MN: Lerner Publications, 1996.

Organizations

American College of Rheumatology. 60 Executive Park South, Suite 150, Atlanta, GA 30329. (404) 633–1870. http://www.rheumatology.org.

Arthritis Foundation. 1330 West Peachtree Street, Atlanta, GA 30309. (404) 872–7100. http://www.arthritis.org.

National Institute of Arthritis and Musculoskeletal and Skin Diseases. http://www.nih.gov/niams.

Web sites

"Arthritis." [Online] http://arthritis.miningco.com (accessed on June 20, 1999).