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Juvenile Idiopathic Arthritis (JIA). By Hatem Galal Abd_Allah Ass. Lecturer Al Azhar University 2014. Juvenile Idiopathic Arthritis (JIA) is a heterogeneous group of diseases characterized by arthritis of unknown origin with onset before age of 16 years.
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Juvenile Idiopathic Arthritis(JIA) By HatemGalalAbd_Allah Ass. Lecturer Al Azhar University 2014
Juvenile Idiopathic Arthritis (JIA) is a heterogeneous group of diseases characterized by arthritis of unknown origin with onset before age of 16 years. • - So, it is not a single disease, but a term that includes all forms of arthritis that begin before a patient is aged 16 years that persist for more than 6 weeks and are of unknown origin. • It is the most common form of childhood arthritis and one of the more common chronic childhood illnesses that causes much disability.
Diagnosis requires a combination of : • Data from history • Physical examination • Laboratory testing • Sound knowledge of differential diagnoses which may present with arthritis in a child
The incidence of JIA is estimated to be 2 to 20 cases per 100,000 children. • The prevalence of JIA is estimated to be 16 to 150 cases per 100,000 children worldwide. • Incidence is a measure of the risk of developing some new conditions within a specified period of time (rate of occurrence of new cases). • Prevalence is the proportion of the total number of cases to the total population (how widespread the disease is).
JIA Classification Criteria • JRA Juvenile rheumatoid arthritis : ( American College of Rheumatology, 1977) • JCA Juvenile Chronic Arthritis : (European League Against Rheumatism, 1978) • JIA Juvenile Idiopathic Arthritis : (The International League of Associations for Rheumatology ILAR ,1997)
ACR (1977) Juvenile Rheumatoid Arthritis (JRA): • - Systemic • - Polyarticular • - Pauciarticular • EULAR (1978) Juvenile Chronic Arthritis (JCA): • - Systemic • - Polyarticular • - Juvenile rheumatoid arthritis • - Pauciarticular • - Juvenile psoriatic arthritis • - Juvenile ankylosing spondylitis
ILAR (1997) Juvenile Idiopathic Arthritis (JIA): • - Systemic • - Polyarticular RF-negative • - Polyarticular RF-positive • - Pauciarticular: Persistent • Extended • - Psoriatic arthritis • - Enthesitis-related arthritis • - Undifferntiatedarthritis
ACREULARILAR No. of onset types367 Age at onset of arthritis16 years16 years16 years Duration of arthritis6 weeks3 months6 weeks Includes JAS & JPsANoYesYes Must exclude other causesYesYesYes
International League of Associations for Rheumatology (ILAR) Classification of JIA 1-Systemic onset JIA
ILAR classification of JIA (cont.) 3- Polyarthritis (RF negative) 4-Polyarthritis (RF positive)
ILAR classification of JIA (cont.) 5-Psoriatic arthritis
ILAR classification of JIA (cont.) 6-Enthesitis-related arthritis
ILAR classification of JIA (cont.) 7- Undifferentiated arthritis Arthritis that fulfills criteria in no category or in ≥2 of the above categories.
OligoarticularJIA • OJIA is the most frequent of the JIA categories (24%–58% of all JIA patients). • To be characterized as having oligoarticularjuvenile idiopathic arthritis (oJIA), a child must have arthritis in four or less joints during the first 6 months of the disease. • OJIA patients are divided into two subcategories: • 1- Persistent oJIA • 2-ExtendedoJIA
PersistentoJIApatients never have acumulative total of more than four joints with arthritis during the course of the disease. • It mainly affects pre-school white caucasian girls with a sex ratio 5:1 . • The knees are the most frequently affected joints followed by the ankle and the wrest, the hip is almost never affected. • ExtendedoJIApatients demonstrate a cumulative total of five or more joints with arthritis during the course of the disease in after the first 6 months of the disease.
Persistent oJIA has the best overall articular outcome of all JIA categories. • Up to half of the persistent oJIA patients will demonstrate monoarticular involvement in a knee joint. • 75% of them achieved remission by adulthood compared to only 12% of those with extended oligoarticular JIA. • The severity of joint symptoms in these patients is usually very mild. It is not uncommon for these children to present with normal or near normal overall physical function, joint swelling, and loss of motion in the knee.
Up to 50% of oJIA cases will evolve to the extended subcategory and 30% will do so in the 2 years after disease onset. • Risk factors for developing more extensive and severe articular involvement : • 1-Arthritis in the wrist, hand or ankle. • 2-Symmetric arthritis. • 3-Arthritis in more than one joint. • 4-Elevated erythrocyte sedimentation rate (ESR). • 5-Positive antinuclear antibodies (ANA) .
Eye involvement occurs in 30% to 50% of oJIA patients. The inflammatory process primarily involves the anterior chamber of the eye and is associated with minimal symptoms in more than 80% of affected children. • Because severe, irreversible eye changes can occur, including corneal clouding, cataract, glaucoma, and partial or total visual loss, patients should be screened at regular intervals and treated by experienced eye specialists.
AMERICAN ACADEMY OF PEDIATRICS GUIDELINES FOR SCREENING EYE EXAMINATIONS ADAPTED FOR JUVENILE IDIOPATHIC ARTHRITIS.
Complications: • 1-Limb Length Discrepancy: • Limb length discrepancy is the result of persistent inflammation in one knee. • The inflamed knee develops an increased blood flow as a result of mediators produced by the inflamed synovium, bringing more nutrients to the bones around the knee. • With additional nutrients the bones will grow more rapidly, causing increased growth on that side , so the arthritic leg will actually grow longer.
This is best accomplished by : 1- Clinical examination. . 2- CT scan and using the computer to measure the exact length of each bone in the leg. 3- Scanogram, an X-ray including a visible ruler so that the bones can be directly measured.
2- Flexion contracture: Bending the knee decreases the pressure in the inflamed joint, and it hurts less. Unfortunately, at the same time, the pain causes the muscles around the knee to spasm. With prolonged muscle spasm, a flexion contracture develops, and it becomes impossible to completely straighten the leg. Children with a leg length discrepancy often continue to hold the longer leg bent in order to keep both legs functionally the same length when walking.
3- Uveitis: Uveitis is a significant complication of pauciarticular JIA. Although the reason for its occurrence has not yet been fully determined, the presence of a positive ANA is strongly correlated with the risk of eye disease. Children with pauciarticular-onset disease who are ANA-positive are much more likely to have eye disease than those who are ANA-negative. It takes the form of inflammatory cells in the anterior chamber of the eye called uveitis or iridocyclitis. The inflammation can lead to damage to the iris with adhesions and irregularity of the pupil. These adhesions are called synechiae. However, it’s usually painless and may go unnoticed for a long period.
4- Jaw Pain: Temporomandibular joint pain (jaw pain) and a decreased ability to open the mouth wide also occur years later in some children with pauciarticular-onset arthritis. It can present as difficulty opening the mouth wide, difficulty chewing, or chronic headaches on one side of the head.