Juvenile Rheumatoid Arthritis (JRA)
Posted: Friday, March 12, 2010
by Jonathan Blood Smyth
In childhood the most frequent rheumatological disease is juvenile rheumatoid arthritis which is also one of the most frequent chronic diseases in this age group. There are a number of different but related disorders which are expressed in chronic inflammation of the joints. It is not clear what causes these conditions and the complexity of the underlying genetic bases for them makes it difficult to clearly distinguish the different types. The naming of the diseases is also under review, with juvenile idiopathic arthritis perhaps gaining ground.
The triggering factors for juvenile rheumatoid arthritis have not been clearly identified, with a possible trigger of trauma or infection developing an autoimmune attack against joint tissues. The synovial lining of the joint increases in bulk and develops chronic inflammation, with perhaps some genetic vulnerability contributing to this process. A group of genes are understood to be involved in the pattern of disease presentation and the nature of its onset. There are many factors which influence the incidence of these types of arthritic diseases, such as how susceptible individuals are and the population types involved.
Approximately fifty percent of all sufferers from juvenile chronic arthritis fall into the oligoarticular type with few joints affected, making it the most common type. With a greater number of joints affected by arthritis, the polyarticular type occurs in about a third of patients, with the remaining patients having the systemic form. Juvenile arthritis patients may be susceptible to acquiring a second autoimmune disorder. The significant disability and pain causes psychological distress, problems with behaviour, depression and anxiety. Girls are more likely to suffer from the many joint affected and poor joint affected forms, with equal incidence in the systemic form.
There are two peaks of age occurrence in the many joint affected or polyarticular type of juvenile arthritis, at between 6 and 12 years and between 1 and 4 years. The fewer joint or oligoarticular form peaks between 2 and 4 years, with no particular pattern in age incidence for the systemic form. How the disease behaves over the first six months indicates which form of the disease the patient will be classed as. With a fewer affected joints form there will be four or less involved over this time period. The polyarticular type has five or more affected joints during the six months since onset. The systemic form does not have this pattern but its symptoms are rashes, arthritis and a fever.
An arthritis must occur for six weeks in a joint to be able to make the diagnosis of juvenile arthritis of the various types. Morning stiffness is a common phenomenon and relates to the fact that the joints stiffen and become more painful after being still for any length of time. The onset of the disease can be slow and gradual or very sudden, with stiffness after resting, joint pain during the day, absences from school and a limp in walking. Inflammatory bowel disease may be associated with these conditions in some cases. Children may not complain particularly about joint pain but rather they may allow a joint to become unused or limp, leading to disuse of the joint or joint contractures.
The onset of juvenile arthritis which comes on systemically is indicated by the child spiking a fever either once or twice daily with the temperature going back to normal each time. This pattern allows some diagnostic usefulness as if does not occur in the event of infections. A short lasting skin rash may also be present over the limbs and the trunk, the child may seem unwell and have joint pains in the larger body joints.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and Local London Physiotherapists. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
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