Juvenile Idiopathic Arthritis (JIA)

Hala Etayari
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JIA - Clinical Manifestations
Arthritis is defined as the presence of joint effusion with reduced range of motion, pain on movement, and/or warmth of the joint. Joint pain generally is aching in quality, mild to moderate in severity and occur with movement. Children differ in how they communicate pain according to developmental age. They may use the limb in a different way, refuse to use the limb and put it in the resting position or they may be irritable.
Joint stiffness and gelling noticed mainly at morning or after prolonged period of inactivity. The parents may notice that the child is slow to get moving or moving awkwardly after sleep or day time nap.
Patterns of joint involvement are often quite characteristic. Thus, symmetrical involvement of large and small joints is typical of polyarticular disease. Arthritis predominantly affecting the joints of the lower extremity characterizes ERA. The presence of hip joint disease is not uncommon in ERA, but rarely occurs in oligoarticular JIA. Psoriatic arthritis tends to be somewhat asymmetrical and involves both large and small joints, sometimes including the distal interphalangeal joints.
Bone pain is not a characteristic of arthritis and should alert the examiner to the possibility of malignancy or infection involving bone.
Other than arthritis, clinical manifestations varies between subtypes. Constitutional symptoms like fatigue, anorexia, weight loss and growth failure found more in systemic and polyarticular JIA.
Extra-articular manifestations:
Generalized growth abnormalities:
Linear growth is retarded during periods of active systemic disease. Mean weight for age and weight per height are significantly diminished in those with polyarticular disease. This occurs secondary to prolonged disease activity and cannot be explained by prolonged use of corticosteroids alone.
Localized growth abnormalities:
During early active disease, development of the ossification centers is accelerated, apparently related to the hyperemia of inflammation and local production of growth factors. The result may be either overgrowth of the affected limb or, ultimately (though much less commonly), premature fusion of the involved physes, resulting in diminished length.
If arthritis occurs in one knee, this may result in leg length discrepancy.
Leg-length inequality may also result from pelvic rotation and scoliosis.
Micrognathia and/or retrognathia may result from growth disturbances of the mandible as a consequence of arthritis in the temporomandibular joint.

Skin and subcutaneous tissue:
One of the characteristic skin manifestations in sJIA is the evanescent rash that appears with fever. Some of the other skin manifestations include dark discoloration of skin over the proximal interphalangeal joints which may indicate chronicity and the subcutaneous rheumatoid nodules. They most commonly occur over the proximal ulna and the Achilles tendon.
Asymmetrical lymphedema of the subcutaneous tissues of one or more extremities has been documented in several children with arthritis.

Occular disease:
Uveitis is the most common extra-articular manifestation of JIA. It is presented most commonly as a chronic asymptomatic anterior uveitis.
Uveitis complications include posterior synichae, band keratopathy, glaucoma, cataract and macular edema. The reported frequency of occurane of uveitis varied considerably from 2-20% and it varies also between JIA subtypes. It occurs in 15-20% of oligoarthritis patients and 5-10% of polyarthritis patients. It is rarely seen in sJIA.(2–4)
Because of the asymptomatic nature of the disease and its vision threatening complications, regular screening by ophthalmology is required. The frequency of screening acording to the American Academy of Pediatric guidelines is determined by the degree of risk and demonstrated in the following tables:

Table 2: Stratification of uveitis risk in JIA
Factor Low risk High risk
Gender Male Female
Age of onset of JIA >6 years <6 years
Type of JIA sJIA Oligoarticular JIA
Duration of JIA >4 years <4 years
ANA Negative Positive
Rheumatoid factor Present Absent


Table 3: American Academy of pediatrics recommendations screening
Level of risk Definition Screening frequency
High Oligoarticular or polyarticular JIA <6 years at onset ANA positive 3-4 monthly
Medium Oligo or polyarticular JIA >6 years at onset ANA negative 6 monthly
Low sJIA 12 monthly



References
Juvenile Idiopathic Arthritis (JIA) Juvenile Idiopathic Arthritis (JIA) 5/11/2016
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