Juvenile idiopathic arthritis (JIA) is an umbrella term which describes a number of conditions involving joint inflammation in children below the age of 16 years. There are seven types described :

1. Systemic JIA, with high fever often accompanied by a rash over the affected joints, lymph node enlargement, and hepatosplenomegaly.
2. Oligoarticular JIA, in which four or less joints are affected in the first six months.
3. Rheumatoid factor-positive polyarticular JIA where five or more joints are affected and the rheumatoid factor is positive. The condition resembles adult rheumatoid arthritis.
4. Rheumatoid factor-negative polyarticular JIA where five or more joints are inflamed but the rheumatoid factor is negative. The eyes are often affected in this variant.
5. Psoriatic-associated JIA in which both psoriasis and JIA are present.
6. Enthesitis-related JIA where joint inflammation is accompanied by tenderness over the points of attachment of tendons and ligaments to the bones, and inflammation elsewhere in the body.
7. Undifferentiated JIA with features non-typical of any category, or with overlapping features.

Signs and symptoms vary from type to type, and even between individuals. Some children do not complain of pain in the beginning. Others may manifest systemic symptoms and signs. Thus the diagnosis of JIA is essentially based on:

1. The clinical features
2. The laboratory findings
3. The family history

Clinical features of JIA

JIA may show up as:

1. Limping in the morning
2. Stiffness of one or more joints especially after a period of rest or sleep
3. Restriction of movement of affected joints
4. Reluctance to use affected joints
5. Fever which persists for days and weeks, sometimes accompanied by a rash over the joints which comes and goes with the fever; loss of weight
6. Joint swelling, redness, and pain
7. Problems with fine motor movements
8. Eye involvement with or without symptoms, consisting mostly of uveitis or iridocyclitis. This may be shown as redness of the eyes, eye pain which worsens on looking at the light, and changes in visual acuity.

The significance of the symptoms and signs in terms of the child’s social and academic activity should also be assessed. A careful family history should be taken to identify autoimmune disorders in the family.

Physical Examination

All joints need to be examined to look for:

1. Inflammation of the synovial membranes
2. Deformity
3. Range of movement

General signs should be looked for, such as fever, lymph node enlargement, hepatosplenomegaly, or skin/nail/hair changes.

Growth should be assessed in terms of height and weight.

If JIA is suspected, ophthalmic examinations should be performed to pick up eye involvement

Laboratory Findings

Blood tests may be required to rule out other conditions that mimic JIA, including:

1. Systemic lupus erythematosus
2. Infections
3. Cancers of childhood
4. Lyme disease
5. Bone diseases

The tests that are ordered may include tests to classify JIA:

1. Rheumatoid factor
2. Anti-nuclear antibodies (ANA)
3. HLA B27

Other tests are useful to detect the presence of autoimmune disease:

1. Complete blood count (CBC)
2. Erythrocyte sedimentation rate (ESR)
3. C-reactive protein (CRP)
4. Other tests such as dsDNA, C3, C4 and immunoglobulin assay
5. X-rays of the joints and of the chest
6. Bone scans
7. Electrocardiogram

Treatment

Treatment of JIA is based on stopping inflammatory activity in the joints, in order to:

1. Relieve the symptoms of pain and restriction of movement
2. Prevent joint damage
3. Promote as normal joint function as possible

Treatment of JIA is multidisciplinary.

Non-steroidal anti-inflammatory drugs

First-line therapy is usually with non-steroidal anti-inflammatory drugs (NSAIDs) . Care must be taken to tailor the dose to the child’s weight. In addition, precautions against gastritis should be observed, such as giving the medication with food. These drugs are most effective when the condition is oligo articular.

Systemic corticosteroids

Systemic corticosteroids are not usually preferred in children due to the toxic effects of prolonged treatment, including growth disturbances, Cushing’s syndrome, cataracts, and osteoporosis. When absolutely required they should be used in as low doses as are necessary to provide remedial effects, and for as limited a time as possible.

Disease-Modifying Anti-Rheumatic Drugs

In case the child does not respond to these agents, a second line of treatment is added. These are called the Disease-Modifying Anti-Rheumatic Drugs (DMARDs), and include various types such as:

1. Immune suppressive agents
2. Biologics such as monoclonal anti-tumor necrotic factor (TNF)-alpha inhibitors , are especially useful in the more active forms of disease, which show rapid progression, and in cases of eye involvement, to prevent blinding complications.
3. Interleukin antagonists, especially IL-1 and IL-6, have been found to induce striking reductions in inflammation and damage in systemic JIA. Monoclonal antibody drugs are available that block IL-1 and IL-6.
4. T-cell costimulation inhibitors prevent antigen-presenting cells from activating T cells.
5. CD20 B cells antagonists
6. Intra-articular corticosteroid injections may be helpful in controlling single joint inflammation, and may obviate the need for other drugs. They are also used when systemic treatment has not brought about remission of inflammation in a few joints, or be used over the period when more advanced treatments have been initiated but their effect has not become evident.

Trials are still underway to determine the safety of long-term use of the biologics. The main concerns appear to be that they may potentially induce infections, autoimmune phenomena, and malignancies.

Auxiliary Measures

Exercising the joints is essential to optimize mobility and to reduce pain. This may be done through physical exercises under the supervision of a physiotherapist, or by activities such as swimming or walking. Children should always be reminded to warm up before they commence exercises as the joints are often stiff.

Psychological support may be required for children who are suffering from depression or anxiety, as well as those who have significant pain.

Permanent disability or pain may indicate the need for corrective surgery such as joint replacement.

Genetic testing is currently being evaluated for its usefulness in predicting disease course as well as in selecting the optimal therapy for various forms of JIA.

References

• https://medlineplus.gov/ency/article/000451.htm
• http://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Juvenile-Arthritis
• https://ghr.nlm.nih.gov/condition/juvenile-idiopathic-arthritis#diagnosis
• https://www.ncbi.nlm.nih.gov/pubmed/22753788
• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3383518/