Types of Juvenile Onset Arthritis

There are three types of Juvenile Rheumatoid Arthritis

The word pauciarticular means "few joints." By definition, children with pauciarticular JRA have arthritis in four or fewer joints during the first 6 months of their disease. In fact, the majority of children with pauciarticular JRA have only one joint involved.
This is the most common form of JRA, accounting for about half of all children with JRA. Most children with this type are quite young at the start of their disease. The average onset is 3 years, but it is not unusual for a child to be as young as 1 yea oldr. Girls are affected more than boys.
This type of arthritis is often asymmetrical, meaning it usually does not affect the same joint on the opposite side of the body. It usually affects the large joints and the most frequently affected joint is the knee, although an ankle, elbow, wrist or a small joint in the hand can also be affected.
Children with this type of JRA often develop arthritis rather acutely and are otherwise healthy. They do not have fever, skin rash or other systemic symptoms that affect all parts of the body. Some children with this type of arthritis have surprisingly little pain despite the presence of a large joint swelling or inability to move the joint properly. Some children may refuse to walk.
Statistically, pauciarticular JRA is likely to be a relatively mild form of arthritis that may resolve completely at some point during childhood. Most children ( 80 to 90 percent) are completely well after a few years.
Children with this type of JRA are susceptible to developing a form of eye inflammation called iritis. This inflammation is most common with children who also have a positive antinuclear antibody blood test. This condition can be silent for a long time and will not cause obvious symptoms such as eye pain, redness, or changes in vision early in its course. Iritis is easily treated with eye drops if it is detected early. If iritis is not detected early, permanent vision loss and even blindness may result. Iritis can only be detected by an ophthalmologist (a physician who specializes in eye disease) who examines the child's eye with an instrument called the slit lamp. Pediatric rheumatologists recommend that all children with pauciarticular JRA have their eyes examined by an ophthalmologist every 3 months.

Polyarticular JRA (2)(13)

About one- third of children with JRA have polyarticular disease. The word polyarticular means "many joints." These children have arthritis in 5 or more joints during the first 6 months of their illness. Except for joint inflammation, these children usually do not appear to be ill. High fevers and skin rashes are not seen in this form of JRA.

Polyarticular JRA usually results in symmetrical arthritis. That is, the same joints are usually affected on both sides of the body (both knees, both wrists, etc.). A wide variety of treatments are used in children with polyarticular arthritis depending on the extent and severity of the disease.

There are two types of polyarticular JRA . They are defined whether or not the child has a positive rheumatoid factor. Children who have a negative Rf factor are called seronegative. Those with a positive test are called seropositive.

Seronegative polyarticular JRA are more common. About 95 percent of children with this type of arthritis are seronegative. Girls are affected about four times as often as boys and children are generally young when the disease starts. The course of seronegative polyarticular JRA is generally one of those flares then remissions. The arthritis tends to be active in the first 3 to 5 years and may quiet down after that.

Seropositive polyarticular JRA is less common. Only about 5 percent of children with this type of arthritis has a positive Rf test. This type often follows a course more like an adult onset disease. This kind of disease tends to be persistent and aggressive . For this reason, pediatric rheumatologists recommend aggressive therapy early in the course of the disease to try to minimize its damage to the affected joints

About 10 percent of children with JRA have a systemic disease. Systemic JRA is equally common among girls and boys. This form is very different from the other types of childhood arthritis in that it causes dramatic symptoms in body systems other than the joints. Children with this type of arthritis have a characteristic high spiking fevers and a rash that may come and go rather quickly. The body temperature becomes elevated once or twice a day and is normal in between . Chills and shaking may occur when the when the child has the fever and he may feel sick. A characteristic pink rash may come and go throughout the day and is more likely to be present when the fever occurs. Serious symptoms include the lymph nodes, liver, and spleen becoming enlarged and inflammation may develop around the heart (pericarditis) or lungs (pleuritis).

When laboratory tests are performed on children with systemic JRA, the results are abnormal. Most children with this type of arthritis develop a severely low red blood cell count (anemia) and a high white blood cell count. These results are consistent with a high level of inflammation in the body.

The diagnosis of systemic JRA requires a careful and difficult workups. Arthritis may not be present early in the course of systemic JRA, which makes diagnosis quite difficult. Children with systemic JRA may have joint and muscle aching without actual joint swelling or decreased range of motion.

The course of systemic JRA is variable. The systemic symptoms of fever and rash eventually disappear, sometimes within months and sometime after a year. Some children have only one episode of disease, followed by complete remission. Some children have flares and remissions repeatedly over time and some develop into severe, persistent arthritis.

Many children with systemic JRA do well when treated with NSAIDs (non-steroidal anti-inflammatory drugs) alone, though some children need to take steroids to control fever or anemia. It is important that the smallest effective dose be used to control the disease, and consults and visits with the pediatric rheumatologist must be maintained during the course of the treatment. Children should be weaned from steroids as soon as the inflammation is controlled to prevent adverse side effects.