Other Names

JRA, Still's disease, Juvenile chronic polyarthritis, Juvenile idiopathic arthritis

What is Juvenile Rheumatoid Arthritis (JRA)?

Juvenile Rheumetoid Arthritis (JRA) is an early-onset disease, characterized by inflammatory swelling of one or more joints. JRA is suspected if chronic inflammatory swelling persists for at least 6 weeks and no other underlying cause can be identified.

Juvenile Rheumatoid Arthritis is unlike Adult Rheumatoid Arthritis. The two conditions are caused by different factors and have a different clinical and biological presentation.

Causes, Incidence and Risk Factors

JRA is not a rare disease. The estimated rate of prevalence is one in every thousand children. These children are generally under the age of 16. Girls are more susceptible than boys.

JRA is an auto-immune disease. It occurs in genetically pre-disposed children. Mutations in the genetic code of immune proteins (proteins found in cells of the immune system) are responsible for this condition. The cause of the genetic mutation is still unknown. Several environmental triggers like, rubella infection, tuberculosis, pneumonia, trauma and psychological stress are suspected to induce JRA. The body produces an increased immune response to such triggers and the auto-antibodies produced attack the joints causing inflammation.

Types of JRA:

• Pauciarticular Onset JRA: 60% of children contract this type. Usually, only the joints on one side of the body are affected (asymmetric involvement of the joints). Large joints such as the knees, hips and shoulders are more likely to be affected than the small joints of the hands and wrist. Joint swelling rather than joint pain is the primary symptom.
  
  
• Polyarticular Onset JRA: 30% of children suffer from this type of JRA. Five or more joints are affected, within the first six months of the onset of the disease. Joint pain is more prevalent than joint swelling. There is a symmetrical involvement of the small joints of the hand. In addition, there may be pain in the joints of the neck and jaw. A factor known as "Rheumatoid Factor" may be present in the blood stream as an indicator of these symptoms, but the cause remains unknown.
  
  
• Systemic Onset JRA: 10% of children can be affected by this type of JRA. Although the cause has not been identified, it is preceded by an illness with prolonged fever that peaks twice daily, rashes (commonly on the chest and trunk), abdominal discomfort and heart or lung diseases.

Signs and Symptoms

• Painful, swollen joints
• Stiff joints that cause limited range of motion
• Altered bone growth
• Visual changes caused by eye inflammation
• Fever and rash on the trunk with systemic JRA

Screening and Diagnosis

Diagnostic Procedures:

• Joint fluid aspiration to rule out infectious causes of joint pain
• X-rays to evaluate the status of the joints

Lab Tests:

• C-reactive Protein Counts, which show up when JRA is present
• Complete Blood Counts (CBC) and Erythrocyte Sedimentation Rate (ESR)
• Hemoglobin tests to show anemia, secondary to chronic inflammation
• Additional tests may be performed to detect markers of autoimmune inflammation like Antinuclear Antibodies Test (ANA), Rheumatoid Factor Test (RF), and HLA Antigens Test.

Treatment

There are many steps to treating JRA.

Medical - Non-steroidal anti-inflammatory drugs (NSAIDs) reduce the joint pain but do not stop the progression of the condition. Indomethacin, Naproxen, Rofecoxib and Valdecoxib are common NSAIDs used.

Agents, known as disease-modifying anti-rheumatic drugs (DMARD), slow the disease process. Such agents are methotrexate and corticosteroids. Steroids function as a bridge therapy and relieve the symptoms of JRA. The NSAID and DMARD drugs are the preferred method to control the disease.

Biological and Immune Therapy - These newer ways of treating JRA are gaining popularity. Biological agents like Ethanercept and Infliximab, work by targeting and destroying inflammation producing proteins.

In Immune Therapy, the body's natural, protective proteins that combat inflammation are introduced at the site of joint destruction, to arrest disease progression.

Physiotherapy - Physical therapy relieves joint pain and restores joint mobility and muscle strength. Occupational therapy can help in rehabilitation and in assessing the future prospects of the affected child. Children with JRA can attend school and lead normal lives.

Outlook

Pauciarticular JRA has a good prognosis but the child must be screened periodically for complications. The prognosis for Polyarticular JRA can be far less satisfactory, because the response to therapy is unpredictable. Polyarticular JRA is more likely to produce joint erosion and cause lasting deformities. A more sever prognosis is indicated if there is early-age onset, persistent fever, and abnormal blood count (elevated platelet levels, for example).

Complications:

• Residual joint deformity
• Growth disturbances
• Secondary Amyloidosis
• Ankylosing Spondylitis
• Eye infections - children with JRA must have regular check-ups with an eye specialist.

Prevention

Unfortunately, there are no preventative measures available at this time. The cause of JRA is still largely unknown.