What is juvenile rheumatoid arthritis?
Juvenile rheumatoid arthritis (JRA), also sometimes called Juvenile idiopathic arthritis (JIA), is a type of arthritis that occurs in children. JRA is a chronic condition characterized by joint inflammation, pain, swelling, redness, and stiffness. It can also damage joints, affect growth, and cause eye problems such as uveitis as well as inflammation of internal organs.
JRA, like adult rheumatoid arthritis, is believed to be an autoimmune disorder. However, unlike adults with RA, children with JRA may outgrow it. The tendency to develop JRA may be inherited, but it is believed that a triggering event is required for it to emerge. Little is known about what triggers JRA.
JRA is classified into three major types based on the number of joints affected and whether or not the internal organs are involved. These types are:
- Pauciarticular (Oligoarthritis) – about 50% of the cases of JRA are of this type; it affects four or fewer joints, usually large joints such as the knees.
- Polyarticular – affects five or more joints, especially those in the fingers and hands, and is seen more frequently in girls than boys.
- Systemic – least common form of JRA; it affects both joints and internal organs. Children with this type may have frequent fevers and rashes that can come and go rapidly.
Symptoms may vary from child to child and will frequently change over time, with flare-ups and remissions. In a few children, the symptoms may persist; in a few others they may permanently disappear. Doctors consider the diagnosis of JRA in children who have had symptoms for at least 6 weeks. These symptoms may include morning stiffness, limping, reluctance to move an affected joint, joint pain and swelling. Children with systemic JRA may have intermittent fever, rash, swollen lymph nodes, and in some cases liver, spleen, and (very rarely) lung involvement. Complications of JRA may include eye inflammation and problems related to joint growth. The disease may cause the affected joints to grow either too quickly or too slowly, causing one arm or leg to be shorter or longer than the other. It may also cause uneven growth in the joint itself. General growth may also be affected by JRA.