Juvenile idiopathic arthritis | Causes,Symptoms and Treatment of (JIA)

What is juvenile idiopathic arthritis (JIA)?

Juvenile Idiopathic Arthritis (JIA) is a chronic disease characterized by persistent joint inflammation; Joint inflammation typically presents as pain, swelling, and reduced mobility. The word “idiopathic” means that the disease is of unknown origin and the word “juvenile” in this case means that symptoms usually appear before the age of 16.

What are the causes of (JIA) juvenile idiopathic arthritis ?

It is not known why 1 to 2 in 1,000 children have juvenile idiopathic arthritis (JIA). JIA is one of the autoimmune diseases, the causes of which remain largely unexplained.

JIA can happen a few weeks after a viral infection, which is usually trivial. However, no trigger event can normally be identified. Genetic factors could also play a role, although JIA (juvenile idiopathic arthritis) is not an inherited disease passed directly from parents to child. It usually affects only one family member.

What are the symptoms of (JIA) juvenile idiopathic arthritis ?

The symptoms of juvenile idiopathic arthritis (JIA) differ depending on the form involved (see below) and their severity varies greatly from one individual to another. They can manifest as swollen and painful joints, fever flares, rashes, and eye inflammation.

In young children, two particular difficulties are added to this. On the one hand, it is difficult to distinguish between swollen joints and plump limbs, common at this age. On the other hand, children usually do not complain of persistent pain. Parents must be extremely attentive to detect, in a slight limp, a particularly sharp gripping movement or a pressure on the first rather than the palm of the hand, any measure aimed at reducing or avoiding pain.

In this group we find pathologies which are differentiated by the number of joints concerned, and by the symptoms associated with them (skin rashes, fever …).

Trace-articular JIA

Trace-articular JIA (juvenile idiopathic arthritis) is characterized by involvement of up to four joints during the first six months of the disease. Subsequently the number of affected joints may increase in this case the oligo-articular JIA will be qualified as extensive. Joint damage to large joints is not symmetrical. This form is frequently associated with uveitis. The female predisposition for this AJI is great.

 

Polyarticular JIA (juvenile idiopathic arthritis) with and without rheumatoid factor is a form of JIA that affects five or more joints from the first six months of disease progression. Arthritis is most often systemic, meaning that all the joints are affected. The rheumatoid factor (RF) form is rare with less than 5% of JIA but it is considered serious. The attacks start in the small joints of the bones of the hand or the foot before spreading to the larger ones. The polyarticular form without FR directly affects all types of joints.

 

In addition to joint symptoms, systemic JIA (juvenile idiopathic arthritis) causes systemic symptoms such as fever or rash. This presence of systemic symptoms is a sign of organ damage in which there are significant signs of inflammation (pericarditis, etc.). It affects at least 5 joints. Psoriatic arthritis (RP) is the association of joint damage with psoriasis. It can also affect adults.

 

Arthritis with enthesitis is arthritis in which there is additionally an inflammation of the area where tendons are inserted into the bone called enthuses. Most often, the large joints of the lower limbs are affected. Boys are more affected than girls. Note that the HLA B27 Ag is found in most of these patients. Undifferentiated arthritis is arthritis that does not fall into the categories listed above.

 

Who is affected by (JIA) juvenile idiopathic arthritis ?

JIA (juvenile idiopathic arthritis) in its systemic form, the oligorticular form and the polyarticular form without rheumatoid factor represent 2/3 of cases. The prevalence of JIA in Europe and North America ranges from 16 to 150 / 100,000. In France, it is estimated that 2,000 to 4,000 people have JIA (juvenile idiopathic arthritis). The diagnostic criteria were specified at the last congress in Edmonton in 2001.

There are now 6 pathologies that fall into this class:

  1. Systemic arthritis or Still’s disease (10-11%)
  2. Juvenile oligoarthritis (50%)
  3.  Polyarthritis with rheumatoid factor
  4.  Polyarthritis without rheumatoid factor
  5. Arthritis with enthesitis or spondyloarthropathies – Psoriatic Arthritis
  6. Unclassified arthritis

1.Systemic (JIA) juvenile idiopathic arthritis

It occurs preferentially between the age of 1 and 5 years, and concerns less than 10% of all cases of JIA (juvenile idiopathic arthritis). It is characterized by the presence, in addition to arthritis, of systemic signs, the main of which is a daily fever for at least 15 days, with two daily peaks above 39 ° C, often accompanied by a rash occurring during feverish peaks.

2.Oligoarticular (JIA) juvenile idiopathic arthritis

The oligoarticular form of JIA (juvenile idiopathic arthritis) is characterized by involvement of up to 4 joints during the first 6 months. Beyond 6 months, the evolution can be persistent oligoarticular or extended (at least five affected joints). Oligoarthritis usually occurs between 2 and 4 years old, but this form can be diagnosed at any age, and often affects girls.

 

Joint involvement is often asymmetric and affects large joints (knees and ankles). The association with uveitis is particularly common. Oligoarthritis is the most common form of JIA (juvenile idiopathic arthritis) (50% of cases).

3.Polyarticular (JIA) juvenile idiopathic arthritis with rheumatoid factor

The presence of an autoantibody called Rheumatoid Factor makes it possible to distinguish the polyarticular form with rheumatoid factor from the polyarticular form without rheumatoid factor. These two forms of JIA (juvenile idiopathic arthritis) are predominantly female. The polyarticular form with rheumatoid factor is quite rare in children. It is often characterized by symmetrical arthritis that initially affects the small joints of the hands and feet, and then spreads to other joints. It is often a severe form of arthritis.

4.Enthesopathies (JIA) juvenile idiopathic arthritis

Arthritis associated with enthesopathies mainly affects boys after the age of 7-8 years. The most common manifestation is oligoarthritis which mainly affects the large joints of the lower limbs associated with enthesitis. Enthesitis is an inflammation of the enthesis, where tendons are inserted into the bones. The evolution of this form is variable.

 

5.Polyarticular (JIA) juvenile idiopathic arthritis  without rheumatoid factor

It concerns between 15 and 20% of cases of JIA (juvenile idiopathic arthritis). It is a complex form of JIA, which can occur at any age, and manifests itself by involvement of 5 or more joints within the first six months of development. Often, the joint involvement is symmetrical and the fever is absent or most often moderate. Association with uveitis is common.

6.(JIA) juvenile idiopathic arthritis associated with Psoriasis

JIA (juvenile idiopathic arthritis) associated with psoriasis is characterized by the presence of arthritis associated with psoriasis. This form is complex in its clinical manifestations and prognosis.

 

Undifferentiated arthritis

Undifferentiated arthritis concerns arthritis that has been progressing for at least 6 months, but which does not fall into any of the other 6 categories, or which falls into several categories. The study of these patients is at least as important, because it can make it possible to redefine the categories proposed.

Arthritis may be present early in the disease, or may not appear until several months or years later. Other symptoms may sometimes appear, such as muscle pain (myalgia) and inflammation of the heart (pericarditis).

The genetic studies carried out on these pathologies show that they are indeed distinct diseases and not different clinical forms of the same disease. These pathologies must be taken care of by a rheumatologist but also by a physiotherapist, psychologist, and child orthopedist to manage the consequences of the disease on the daily life of the child.

Treatments of (JIA)

Since 2000, the arrival of biotherapies has revolutionized the management and prognosis of the most severe forms of these diseases. It should be noted that methotrexate remains the second-line drug of reference. In the systemic form, however, the effect of methotrexate and anti-TNF-alpha agents is often disappointing. In these patients, other treatments are currently used and / or under study: thalidomide, the IL1 receptor antagonist and the anti IL6 receptor monoclonal antibody (ARD).

Medical treatment for (JIA)

The main goal of drug therapy is the lasting regression (remission) of disease activity by inhibiting inflammatory mechanisms. The objective is to protect the young patient from sequelae in the joints or organs.

 

To this end, the rheumatologist establishes a personalized treatment for his patient. It takes into account the specific form of the disease, inflammatory activity and concomitant symptoms. Nonsteroidal anti-inflammatory drugs (NSAIDs), cortisone-based preparations, basic treatments and biotherapies are used in this context. Dosage is prescribed based on weight.

 

You will find further information on drug treatment (drugs, action, side effects) and recommendations for vaccination in the brochure “Childhood Arthritis” published by the Swiss League against Rheumatism.

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