Juvenile idiopathic arthritis

What is juvenile idiopathic arthritis?

Arthritis is an inflammation of the joints, with pain or stiffness. It may be acute or chronic.

Acute arthritis is also called septic arthritis and may affect one or more joints.

Chronic arthritis is also known as juvenile idiopathic arthritis (JIA). There are three types of JIA, which are diagnosed according to symptoms and blood tests.

• Oligoarticular JIA - the most common kind of childhood arthritis, which often starts at the age of two or three. The problem is limited to four joints or fewer, which become swollen and painful. Sometimes the eyes are affected, too. It is also known as pauciarticular arthritis.
• Polyarticular JIA - affects five or more joints. It can start at any age, from a few months onwards, and usually spreads quite quickly from one joint to another. Children often feel generally unwell, sometimes with a fever.
• Systemic onset JIA - affects the whole body, and causes fever and rashes as well as inflamed and painful joints. It usually starts in children under five but can affect children of any age. It used to be called Still's disease.

About one in 1,000 children has arthritis. In many cases, the inflammation stops in late childhood, but about one-third of children affected have problems that last into their adult life.

Causes of juvenile idiopathic arthritis

Infection is an important but treatable cause of JIA, especially in the under-twos. Infections include bacteria and viruses, such as mumps, rubella, herpes and Lyme disease.

Polyarticular JIA may be caused by many different things including inflammatory bowel disease, such as Crohn's disease, inflammatory blood vessel disease or vasculitis, blood disorders such as sickle cell anaemia or haemophilia, malignancy, cystic fibrosis and connective tissue disorders often because of problems linked to the immune system, such as lupus and ankylosing spondylitis.

The cause of systemic juvenile idiopathic arthritis is unknown. Genetic factors may play a part and disease may be triggered by a viral infection (although none has been identified), which causes overactivity of the immune system.

Symptoms of juvenile idiopathic arthritis

Symptoms depend on the type of arthritis and joints affected but include painful, swollen, stiff and tender joints, an acute illness with fever and lethargy, loss of appetite, weight loss and refusal to use the affected joint or limb.

In systemic arthritis there may be high fever, rash, swollen glands and muscle pain lasting for at least two weeks, associated with anaemia and inflammation of other organs, including the heart or eye. Joints may develop deformities over time.

Diagnosing juvenile idiopathic arthritis

Diagnosis is made on the basis of a combination of clinical examination, x-rays, bone scans and blood tests. It may be necessary to take a sample of fluid from the joint to test for infectious organisms.

Treatments for juvenile idiopathic arthritis

Septic arthritis needs urgent treatment with antibiotics to reduce the risk of damage to the joint.

Treatments include drugs to control pain and inflammation, steroids (in more severe cases, which may include injections into the joint) and powerful medicines that alter the immune system (such as methotrexate, salazopyrin, cyclosporine and etanercept).

Physiotherapy to keep the joints mobile and build muscle strength is also important. Splinting or surgery is sometimes needed.

In most cases, children recover from juvenile arthritis with few long-term problems. However, some do experience considerable difficulties from ongoing disease or damaged joints throughout adolescence and into adulthood.

Case study

Oliver was 18 months old when he developed a sore throat, earache and fever. The doctor prescribed antibiotics, but the symptoms didn't go away. Oliver winced whenever he was touched. He wouldn't move or eat and his weight began to drop. "We were getting desperate," says Oliver's mum, Miriam. "But the doctors still said it was a virus."

Finally, when Oliver developed a rash on his stomach, the doctors got worried about meningitis and he was sent to hospital for tests. But Miriam and her partner had to wait another three weeks before the diagnosis of arthritis was confirmed.

"The trouble with systemic onset juvenile chronic arthritis is that no single test can prove what it is. First they had to rule out leukaemia, cancer and other forms of arthritis. It was 12 weeks before we knew what it was.

"Oliver went on medication and we had to keep him mobile every day to stop contractures. Sometimes it was heartbreaking to coax him into moving when there were tears pouring down his face."

However, the treatment and hard work seem to be working. "Now Oliver looks like any other two-year-old."