Juvenile Idiopathic Arthritis (The Medical Bit)

What is juvenile idiopathic arthritis?

Junior idiopathic arthritis (JIA) is literally inflammation, involving swelling, pain, stiffness and restricted movement, of one or more joints which started before a person is 16-years-old and for which the cause is unknown.

There are several types of JIA:

• Oligoarticular JIA - the most common kind of JIA affecting two thirds of cases, which often starts at the age of two or three. The problem is limited to only a few joints, most commonly the knees. It is often mild and transient, leaving no damage. However, there is an associated risk of inflammation of the eye (' chronic anterior uveitis') which can affect vision but doesn't cause redness of the eye, so regular eye checks are important if you have this type of JIA.
• Polyarticular JIA - this type of JIA affects more joints, usually the small joints of the hands and feet as well as the hips, knees and neck. It can then spread over months to other joints and the child may feel generally unwell. It may continue into adulthood or may go into remission.
• Extended oligoarthritis - starts as oligoarthritis but then spreads to other joints, possibly causing damage and requiring stronger drug therapies such as methotrexate.
• Ehthesitis-related JIA - this form of JIA affects the areas of the bone where the tendons attach, particularly in the leg and spine. It can cause stiffness and there may be a family history of HLA-B27related bowel disease or ankylosing spondylitis (another inflammatory joint condition). This form can cause a different type of uveitis where this is redness of the eye.
• Psoriatic Arthritis - this form of JIA is associated with the skin disease 'psoriasis' but the inflamed joints may occur before the skin rash or nail changes of psoriasis. If typically affects the finger and toe joints, but can affect any joint and is also associated with a non-red uveitis.
• Systemic onset JIA - the rarest type of JIA, affects the whole body, and can cause general malaise, fever and rashes, enlarged glands and even pericarditis as well as, often late in the disease, inflamed and painful joints. It usually starts in children under five but can affect children of any age.
• Undifferentiated arthritis - some children don't fit any of the above patterns but still have inflamed joints.

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

JIA is not directly inherited but is believed to be due to a combination of genetic factors, possibly with some form of environmental trigger factor such as an infection that hasn't yet been demonstrated. However, there is no evidence that infection actually causes JIA, just that it may affect the body's response afterwards.

Diagnosis

There is no specific test for JIA. The diagnosis is made by the clinical picture, and then by confirming inflammation with blood tests and X-rays of any painful or swollen joints. MRI or ultrasound may be done and aspiration of fluid from any swollen joints to look for possible infection or other signs of inflammation.

Occasionally inflammation of the lining of the heart (pericarditis) occurs with the systemic-onset type JIA so chest X-ray and echocardiogram may be useful.

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, sometimes associated with anaemia and inflammation of other organs, including the heart or eye. Joints may develop deformities over time.

Treatments for juvenile idiopathic arthritis

Treatments include drugs to control pain and inflammation, steroids (in more severe cases, which may include injections into the joint) and, if the inflammation does not settle, the second line drugs, called disease modifying anti-rheumatic drugs (DMARDs), that alter the immune system may be considered necessary (such as methotrexate, salazopyrin cyclosporine) A new range of medications have been developed called 'Biological therapies' (such as infliximab and etanercept) also suppress the immune system's role in JIA and can be very effective in severe cases.

Physiotherapy to keep the joints mobile and build muscle strength is also important. Splinting or, later on if there has been deformity of growth, surgery is sometimes needed.

If the disease has affected other areas such as the eye or pericardium, specialist opinion and management may be necessary.

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.