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Juvenile arthritis (JA), also called juvenile rheumatoid arthritis (JRA), refers to a number of different conditions, all of which strike children, and all of which have immune-mediated joint inflammation as their major manifestation. JRA is also known as juvenile idiopathic arthritis or JIA. The European League Against Rheumatism, or EULAR, refers to the disorder as juvenile chronic arthritis, or JCA.
The skeletal system of the body is made up of different types of the strong, fibrous tissue known as connective tissue. Bone, cartilage, ligaments, and tendons are all forms of connective tissue which have different compositions, and thus different characteristics.
The joints are structures which hold two or more bones together. Some joints (synovial joints) allow for movement between the bones being joined (called articulating bones). The simplest model of a synovial joint involves two bones, separated by a slight gap called the joint cavity. The ends of each articular bone are covered by a layer of cartilage. Both articular bones and the joint cavity are surrounded by a tough tissue called the articular capsule. The articular capsule has two components: the fibrous membrane on the outside, and the synovial membrane (or synovium) on the inside. The fibrous membrane may include tough bands of fibrous tissue called ligaments, which are responsible for providing support to the joints. The synovial membrane has special cells and many capillaries (tiny blood vessels). This membrane produces a supply of synovial fluid which fills the joint cavity, lubricates it, and helps the articular bones move smoothly about the joint.
In JA, the synovial membrane becomes intensely inflamed. Usually thin and delicate, the synovium becomes thick and stiff, with numerous infoldings on its surface. The membrane becomes invaded by white blood cells, which produce a variety of destructive chemicals. The cartilage along the articular surfaces of the bones may be attacked and destroyed, and the bone, articular capsule, and ligaments may begin to be worn away (eroded). These processes severely interfere with movement in the joint.
JA specifically refers to chronic arthritic conditions which affect a child under the age of 16 years, and which last for a minimum of three to six months. JA is often characterized by a waxing and waning course, with flares separated by periods of time during which no symptoms are noted (remission). Some literature refers to JA as juvenile rheumatoid arthritis, although most types of JA differ significantly from the adult disease called rheumatoid arthritis, in terms of symptoms, progression, and prognosis.
Causes and symptoms
A number of different causes have been sought to explain the onset of JA. There seems to be some genetic link, based on the fact that the tendency to develop JA sometimes runs in a particular family, and based on the fact that certain genetic markers are more frequently found in patients with JA and other related diseases. Many researchers have looked for some infectious cause for JA, but no clear connection to a particular organism has ever been made. JA is considered by some to be an autoimmune disorder. Autoimmune disorders occur when the body's immune system mistakenly identifies the body's own tissue as foreign, and goes about attacking those tissues, as if trying to rid the body of an invader (such as a bacteria, virus, or fungi). While an autoimmune mechanism is strongly suspected, certain markers of such a mechanism (such as rheumatoid factor, often present in adults with such disorders) are rarely present in children with JA.
Joint symptoms of arthritis may include stiffness, pain, redness and warmth of the joint, and swelling. Bone in the area of an affected joint may grow too quickly, or too slowly, resulting in limbs which are of different lengths. When the child tries to avoid moving a painful joint, the muscle may begin to shorten from disuse. This is called a contracture.
Symptoms of JA depend on the particular subtype. According to criteria published by the American College of Rheumatology (ACR) in 1973 and modified in 1977, JRA is classified by the symptoms that appear within the first six months of the disorder:
- Pauciarticular JA: This is the most common and the least severe type of JA, affecting about 40-60% of all JA patients. This type of JA affects fewer than four joints, usually the knee, ankle, wrist, and/or elbow. Other more general (systemic) symptoms are usually absent, and the child's growth usually remains normal. Very few children (less than 15%) with pauciarticular JA end up with deformed joints. Some children with this form of JA experience painless swelling of the joint. Some children with JA have a serious inflammation of structures within the eye, which if left undiagnosed and untreated could even lead to blindness. This condition is known as uveitis, and affects about 20% of children diagnosed with JRA. While many children have cycles of flares and remissions, in some children the disease completely and permanently resolves within a few years of diagnosis.
- Polyarticular JA: About 40% of all cases of JA are of this type. More girls than boys are diagnosed with this form of JA. This type of JA is most common in children up to age three, or after the age of 10. Polyarticular JA affects five or more joints simultaneously. This type of JA usually affects the small joints of both hands and both feet, although other large joints may be affected as well. Some patients with arthritis in their knees will experience a different rate of growth in each leg. Ultimately, one leg will grow longer than the other. About half of all patients with polyarticular JA have arthritis of the spine and/or hip. Some patients with polyarticular JA will have other symptoms of a systemic illness, including anemia (low red blood cell count), decreased growth rate, low appetite, low-grade fever, and a slight rash. The disease is most severe in those children who are diagnosed in early adolescence. Some of these children will test positive for a marker present in other autoimmune disorders, called rheumatoid factor (RF). RF is found in adults who have rheumatoid arthritis. Children who are positive for RF tend to have a more severe course, with a disabling form of arthritis which destroys and deforms the joints. This type of arthritis is thought to be the adult form of rheumatoid arthritis occurring at a very early age.
- Systemic onset JA: Sometimes called Still disease (after a physician who originally described it), this type of JA occurs in about 10-20% of all patients with JA. Boys and girls are equally affected, and diagnosis is usually made between the ages of 5-10 years. The initial symptoms are not usually related to the joints. Instead, these children have high fevers; a rash; decreased appetite and weight loss; severe joint and muscle pain; swollen lymph nodes, spleen, and liver; and serious anemia. Some children experience other complications, including inflammation of the sac containing the heart (pericarditis); inflammation of the tissue lining the chest cavity and lungs (pleuritis); and inflammation of the heart muscle (myocarditis). The eye inflammation often seen in pauciarticular JA is uncommon in systemic onset JA. Symptoms of actual arthritis begin later in the course of systemic onset JA, and they often involve the wrists and ankles. Many of these children continue to have periodic flares of fever and systemic symptoms throughout childhood. Some children will go on to develop a polyarticular type of JA.
- Spondyloarthropathy: This type of JA most commonly affects boys older than eight years of age. The arthritis occurs in the knees and ankles, moving over time to include the hips and lower spine. Inflammation of the eye may occur occasionally, but usually resolves without permanent damage.
- Psoriatic JA: This type of arthritis usually shows up in fewer than four joints, but goes on to include multiple joints (appearing similar to polyarticular JA). Hips, back, fingers, and toes are frequently affected. A skin condition called psoriasis accompanies this type of arthritis. Children with this type of JA often have pits or ridges in their fingernails. The arthritis usually progresses to become a serious, disabling problem.
As of 2003, there is some disagreement among specialists about the classification of JRA. Some prefer the EULAR classification, also introduced in 1977, to the ACR system. In 1997, the World Health Organization (WHO) met in Durban and issued a new classification system for JRA known as the Durban criteria, in an attempt to standardize definitions of the various subtypes of JRA. None of the various classification systems, however, are considered fully satisfactory as of early 2004.
Diagnosis of JA is often made on the basis of the child's collection of symptoms. Laboratory tests often show normal results. Some nonspecific indicators of inflammation may be elevated, including white blood cell count, erythrocyte sedimentation rate, and a marker called C-reactive protein. As with any chronic disease, anemia may be noted. Children with an extraordinarily early onset of the adult type of rheumatoid arthritis will have a positive test for rheumatoid factor.
Treating JA involves efforts to decrease the amount of inflammation, in order to preserve movement. Medications which can be used for this include nonsteroidal anti-inflammatory agents (such as ibuprofen and naproxen). Oral (by mouth) steroid medications are effective, but have many serious side effects with long-term use. Injections of steroids into an affected joint can be helpful. Steroid eye drops are used to treat eye inflammation. Other drugs which have been used to treat JA include methotrexate, sulfasalazine, penicillamine, and hydroxychloroquine. Physical therapy and exercises are often recommended in order to improve joint mobility and to strengthen supporting muscles. Occasionally, splints are used to rest painful joints and to try to prevent or improve deformities.
The Food and Drug Administration (FDA) approved a new drug, etanercept, marketed under the brand name Enbrel, in 1999. It is the most dramatic advancement in treating JRA in recent years. A study by Children's Hospital Medical Center in Cincinnati, Ohio, released in 1999, showed the drug was effective in 75% of children with severe JRA. The drug eases joint pain, reduces swelling, and improves mobility.
In 2003, a group of Japanese researchers noted that the blood serum of patients with JRA contains elevated levels of interleukin-6, a cytokine (nonantibody protein) that is critical to regulation of the immune system and blood cell formation. Because interleukin-6 is also associated with inflammation, the researchers think that compounds inhibiting the formation of interleukin-6 might provide new treatment options for JRA.
Alternative treatments that have been suggested for arthritis include juice therapy, which can work to detoxify the body, helping to reduce JA symptoms. Some recommended fruits and vegetables to include in the juice are carrots, celery, cabbage, potatoes, cherries, lemons, beets, cucumbers, radishes, and garlic. Tomatoes and other vegetables in the nightshade (potatoes, eggplant, red and green peppers) are discouraged. As an adjunct therapy, aromatherapy preparations utilize cypress, fennel, and lemon. Massage oils include rosemary, benzoin, chamomile, camphor, juniper, and lavender. Other types of therapy which have been used include acupuncture, acupressure, and body work. Nutritional supplements that may be beneficial include large amounts of antioxidants (vitamins C, A, E, zinc, selenium, and flavenoids), as well as B vitamins and a full complement of minerals (including boron, copper, manganese). Other nutrients that assist in detoxifying the body, including methionine, cysteine, and other amino acids, may also be helpful. A number of autoimmune disorders, including JA, seem to have a relationship to food allergies. Identification and elimination of reactive foods may result in a decrease in JA symptoms. Constitutional homeopathy can also work to quiet the symptoms of JA and bring about balance to the whole person.
The prognosis for pauciarticular JA is quite good, as is the prognosis for spondyloarthropathy. Polyarticular JA carries a slightly worse prognosis. RF-positive polyarticular JA carries a difficult prognosis, often with progressive, destructive arthritis and joint deformities. Systemic onset JA has a variable prognosis, depending on the organ systems affected, and the progression to polyarticular JA. About 1-5% of all JA patients die of such complications as infection, inflammation of the heart, or kidney disease.
Articular bones — Two or more bones which are connected with each other via a joint.
Cytokine — A general term for nonantibody proteins released by a specific type of cell as part of the body's immune response.
Idiopathic — Of unknown cause or spontaneous origin. JRA is sometimes called juvenile idiopathic arthritis or JIA because its causes are still not fully known.
Joint — A structure that holds two or more bones together.
Rheumatology — The branch of medicine that specializes in the diagnosis and treatment of disorders affecting the muscles and joints.
Synovial joint — A particular type of joint that allows for movement in the articular bones.
Synovial membrane — The membrane that lines the inside of the articular capsule of a joint and produces a lubricating fluid called synovial fluid.
Uveitis — Inflammation of the pigmented vascular covering of the eye, which includes the choroid, iris, and ciliary body. Uveitis is a common complication of JRA.
Because so little is known about what causes JA, there are no recommendations available for how to avoid developing it.
Beers, Mark H., MD, and Robert Berkow, MD., editors. "Juvenile Rheumatoid Arthritis." Section 19, Chapter 270 In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2002.
Behrman, Richard, et al., editors. Nelson Textbook of Pediatrics. 16th ed. Philadelphia: W. B. Saunders Co., 2000.
Kredich, Deborah Welt. "Juvenile Rheumatoid Arthritis." In Rudolph's Pediatrics, edited by Abraham M. Rudolph. Stamford:McGraw-Hill, 2002.
Peacock, Judith. Juvenile Arthritis. Mankato, MN: LifeMatters Books, 2000.
de Boer, J., N. Wulffraat, and A. Rothova. "Visual Loss in Uveitis of Childhood." British Journal of Ophthalmology 87 (July 2003): 879-884.
Henderson, Charles W. "Etancercept a Dramatic Advancement in Treatment, Say Researchers." Immunotherapy Weekly April 2, 2000.
Kotaniemi, K., A. Savolainen, A. Karma, and K. Aho. "Recent Advances in Uveitis of Juvenile Idiopathic Arthritis." Survey of Ophthalmology 48 (September-October 2003): 489-502.
Larkin, Marilynn. "Juvenile Arthritis Helped by Resistance Exercise." Lancet November 20, 1999: 1797.
Manners, P., J. Lesslie, D. Speldewinde, and D. Tunbridge. "Classification of Juvenile Idiopathic Arthritis: Should Family History Be Included in the Criteria?" Journal of Rheumatology 30 (August 2003): 1857-1863.
Moran, M. "Autoimmune Diseases Could Share Common Genetic Etiology." American Medical News 44, no. 38 (October 8, 2001): 38.
Yokota, S. "Interleukin 6 as a Therapeutic Target in Systemic-Onset Juvenile Idiopathic Arthritis." Current Opinion in Rheumatology 15 (September 2003): 581-586.
American College of Rheumatology. 1800 Century Place, Suite 250, Atlanta, GA 30345. (404) 633-3777. http://www.rheumatology.org.
Arthritis Foundation. 1330 West Peachtree St., Atlanta, GA 30309. (404) 872-7100. http://www.arthritis.org.
National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse. National Institutes of Health, 1 AMS Circle, Bethesda, MD 20892. (301) 495-4484. http://www.nih.gov/niams.
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Questions and Answers About Juvenile Rheumatoid Arthritis. NIH Publication No. 01-4942. Bethesda, MD: NIAMS, 2001. http://www.niams.nih.gov/hi/topics/juvenile_arthritis/juvarthr.htm.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
ju·ve·nile ar·thri·tis, juvenile rheumatoid arthritis
chronic arthritis beginning in childhood, most cases of which are pauciarticular, that is, affecting few joints. Several patterns of illness have been identified. In one subset, primarily affecting girls, iritis is common and antinuclear antibody is usually present; another subset, primarily affecting boys, frequently includes spinal arthritis resembling ankylosing spondylitis. Some cases are true rheumatoid arthritis beginning in childhood and characterized by the presence of rheumatoid factor and destructive deforming joint changes, often going into remission at puberty.
See also: Still disease.
See also: Still disease.
Synonym(s): juvenile chronic arthritis
Farlex Partner Medical Dictionary © Farlex 2012
ju·ve·nile ar·thri·tis, juvenile rheumatoid arthritis (jū'vĕ-nil ahr-thrī'tis, rū'mă-toyd)
Chronic arthritis beginning in childhood, most cases of which are pauciarticular, i.e., affecting few joints. Several patterns of illness have been identified: in one subset, primarily affecting girls, iritis is common and antinuclear antibody is usually present; another subset, primarily affecting boys, frequently includes spinal arthritis resembling ankylosing spondylitis; some cases are true rheumatoid arthritis beginning in childhood and characterized by the presence of rheumatoid factor and destructive deforming joint changes, often undergoing remission at puberty.
See also: Still disease
See also: Still disease
Medical Dictionary for the Health Professions and Nursing © Farlex 2012