"Juvenile" or "childhood" arthritis is a disease occurring in children below the age of sixteen. The affected children experience pain, stiffness and swelling in one or more joints. This trio is called inflammation. This inflammation is present for more than six weeks. The prevalent form of juvenile arthritis is "juvenile rheumatoid arthritis" (JRA). Almost, 50,000 children in the United States are suffering from this disease.
There are three major types:
polyarticular arthritis
pauciarticular JRA
systemic JRA
The first type affects more girls than boys. The small joints of the hand and the weight-bearing joints are affected. There is swelling or pain in minimum 5 joints.
In the second type, the knee and wrist joints are generally affected. Inflammation of maximum four joints is observed. Additionally, the iris may be inflamed with or without active joint symptoms.
In the third type, there is initial fever that increases in the evening and abruptly comes back to normal. During fever, the child may develop a rash. This rash may all of a sudden disappear and reappear. The spleen and lymph nodes increase in size. Finally, many joints of the body are inflamed.
The most common signs and symptoms of juvenile rheumatoid arthritis are:
Pain. While your child might not complain of joint pain, you may notice that he or she limps — especially first thing in the morning or after a nap.
Swelling. Joint swelling is common but is often first noticed in larger joints like the knee.
Stiffness. You might notice that your child appears clumsier than usual, particularly in the morning or after naps.
Juvenile rheumatoid arthritis can affect one joint or many. In some cases, juvenile rheumatoid arthritis affects the entire body — causing swollen lymph nodes, rashes and fever. Like other forms of arthritis, juvenile rheumatoid arthritis is characterized by times when symptoms flare up and times when symptoms disappear.
The cause of juvenile rheumatoid arthritis is unknown. Like adult-type RA and many other related diseases, JRA is an autoimmune disease. This means that the body’s immune system mistakenly attacks the tissues it is supposed to protect.
The chronic inflammation of the synovium (the lining of the joints) is linked to greater-than-normal activity of the immune system.
Normally, the immune system fights “assaults” by “invaders” such as infections or blood or tissue from another person.
The immune system produces specialized cells and proteins, which are released into the bloodstream to fight off the “invaders.” One important type of immune protein is called an antibody.
In autoimmune diseases, the cells and antibodies of the immune system attack the body’s own tissues. In the case of arthritis, the attack is directed against the synovium, which becomes inflamed.
The inflammation causes the synovium to thicken and grow abnormally. As the synovium expands outside of the joint, it presses on and eventually damages the bone and cartilage of the joint and the surrounding tissues such as ligaments and tendons.
We do not know what causes the inappropriate autoimmune response.