Juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA abbreviated, older Synonyms: Juvenile rheumatoid arthritis, juvenile chronic arthritis) is a chronic inflammatory disease of the joints in childhood (juvenile). As the systemic juvenile arthritis (also called Still’s disease) and other forms of juvenile rheumatism, the JIA is part of the Department of Paediatric Rheumatology.

People think that it is triggered by external factors such as “infectious agents”. Diagnosis is based on the following complaints of one or more joints in a child (<16 years): (tolerable usually) pain, warmth, redness, swelling, effusion and limitation of movement for more than six weeks continuously, without any other cause (“diagnosis of exclusion”).

Epidemiology

The incidence (annual incidence) is estimated at about 5 – 6 per 100,000 children under 16. It is estimated that 20 – 30 per 100,000 children under 16 have a rheumatic disease (prevalence). Thus, this disease group sees most patients in a paediatric rheumatology clinic.

The majority of these children have a oligo-arthritis. If several members of a family are affected, the risk increases 10-fold. Monozygotic twins of patients have an even higher risk.

Disease progression

The prognosis is mixed. In the long-term course about 40% of patients have only a mild arthritis that is characterized by medical and physical therapy and good control. Systemic signs may relapse occasionally occur with long remissions. One hand, 20 – 30% lasting remissions are described, and there are progressive, relatively refractory gradients with irreversible joint destruction and organ complications.

The long-term course occurs with chronic progressive joint involvement. In addition to all the major joints, the small joints can be affected too. A local or systemic illness caused by osteoporosis can cause immobility. Chronic involvement of the cervical spine can fuse the vertebrae.

A particularly unfavorable prognosis, is the combination of progressive arthritis with persistent systemic symptoms, persistent signs of inflammation in the laboratory and platelet counts over 500/nl.

Complications: In 50 – 10% of cases with persistent high disease activity of forms of amyloidosis, this can lead to irreversible organ damage. A further complication is the so-called macrophage activation syndrome, characterized by the sudden onset of high fever, liver and spleen enlargement, loss of awareness, and skin rashes.

Advances in immunosuppressive therapy have seen the incidence of lethal complications, significantly decreased. There is a total mortality of juvenile idiopathic arthritis affecting less than 1% but more than half of the systemic-onset form.

Juvenile arthritis, rheumatoid factor positive (-ICD 10: M08.0)

This subtype can be classified according to the ILAR and be diagnosed when two criteria are met: Five or more joints inflamed during the first six months and second, at least twice at intervals of at least three months have proof positive of rheumatoid disease.

Others need to be excluded (i) a medically backed psoriasis in the patient or first-degree relatives, (ii) an arthritis in an HLA-B27-positive boy under the age of six, (iii) ankylosing spondylitis, enthesitis-related arthritis, sacroiliitis with inflammatory bowel disease, Reiter’s syndrome, acute anterior Uveiitis in the first-degree and (iiii) signs of systemic arthritis.

Epidemiology

50 – 10% of patients with juvenile idiopathic arthritis are among this subgroup. It affects about 90% of girls, the onset date is mainly between the 7th and 13th year of life.

Symptoms at the start

The disease is similar to rheumatoid arthritis in adults. Early on the joints are affected, typically symmetrically on the wrist, finger and toe joints. Basically, where each joint is affected, there may be considerable functional within months and some irreversible restrictions. As with the adult form on the extensor surfaces of the extremities, subcutaneous rheumatoid nodules were observed. This may also occur on internal organs.

The arthritis may be accompanied by small and medium-sized arteries and the involvement of the internal organs. In patients with active rheumatoid arthritis, in addition they may also have general symptoms such as growth arrest, delay of growth and development, low-grade fever, reduced general condition, buckling performance, weight loss, emotional liability, lymph node swelling and mild pain. The diagnosis requires laboratory findings for the detection of rheumatoid factors in at least two tests every three months.

Juvenile idiopathic arthritis effects

Joint destruction occurs in the course of this form to significantly fewer and later than the (adult) form, where such are visible after only a few months. However, there also develops typical deformities of the wrists and the finger (flexion contractures of the proximal finger joints). The prognosis in late diagnosis is advanced joint contractures and marked axial deformities. Only 10% of these patients will recover. With early diagnosis, the functional prognosis of consistent medication, physical therapy and orthotic devices can improve it significantly.

Juvenile idiopathic arthritis with enthesitis (ICD-10: M08.8)

An enthesitis or enthesopathy is an inflammation or pain of ligaments and tendons. Typically, to the points of attachment of the Achilles tendon (heel), the patella, the tibia, and less frequently to the plug-and flexures of the feet and hands, the iliac crest, the coccyx and the chest. This subtype of juvenile idiopathic arthritis is classified according to the ILAR diagnosis when the following criteria are met: 1) inflammation of multiple joints and 2) inflammation of tendons or ligaments.

If the latter is lacking, there must be met in addition to the two joints of the following five criteria for diagnosis: a) pain at the junction between the pelvis and lumbar spine and inflammatory spinal pain, b) presence of HLA-B27, c) at the beginning of arthritis a boy older than his years d) front (uveitis) of the eye, with pain, redness or photophobia, and e) the presence of a disease following first-degree relatives:

(i) A front (uveitis) of the eye (pain, redness or photophobia), (ii), ankylosing spondylitis, (iii) arthritis with enthesitis, (iiii) inflammation of the pelvic spine transition to chronic inflammatory bowel disease.

Others needed to be excluded (i) a medically backed psoriasis in the patient or a first-degree relative, (ii) rheumatoid factor detection in two tests at an interval of at least three months and (iii) signs of systemic arthritis.

This subgroup was introduced in the classification of the International League of Associations of Rheumatology in order to concentrate on the basis of modified criteria, most children of the previously mentioned late form of juvenile idiopathic oligoarthritis and children with juvenile spondyloarthropathy can be distinguishable in classification. It

Epidemiology

Approximately 50 – 10% of children of juvenile idiopathic arthritis can be classified in this subgroup. The age of onset is 9 – 13 years and about 20% are girls.

Symptoms

Typically, there is pain at the points of attachment of the Achilles tendon in the heel, back of the tendon of the patella, the tibia, the extensor surfaces of the extremities and the pelvis. These are more pronounced at night, in the early morning hours and during exercise and lead to significant functional impairment and poor posture (flat back deformity of the spine with the lumbar spine and rounded shoulders, incorrect loading of the foot).

Arthritis occurs mainly in the first legs with asymmetrical involvement of large and small joints. It is not uncommon for an entire foot to have an inflammatory change. Often, the shoulders and jaw joints affected. An exclusive involvement of the spine is very rare in childhood. Laboratory results show the disease usually is accelerated when ESR and an elevated C-reactive protein is present.

The parameters can, despite persistent inflammation in the course, fall slowly. In about 75% affected children can demonstrate the genetic marker HLA-B27 (found in the general population: about 8%).

Juvenile psoriatic arthritis (ICD-10: L40.5)

This subtype can be classified according to the ILAR and can be diagnosed if the following two criteria are met: arthritis and psoriasis (psoriasis).

Epidemiology

Ca. 50 – 10% of children of juvenile idiopathic arthritis can be classified in this subgroup. The age of onset is about 6 – 14 years and about 65% of sufferers are girls.

Symptoms

Psoriasis can precede the joint manifestations by many years. Only 10% of patients occur both at the same time. Typical sites for a first manifestation of psoriasis are the hairline, the extensor surfaces of joints to mechanical stress at the exposed navel region, and the region around the anus. Nail detachment (onycholysis) is typical for children, as it is distinguishable from a fungal disease.

Characteristics are an infestation of all the joints of a digit (dactylitis) and pitting of the nail of that finger. Psoriatic arthritis can be shown in a clinical course with similar joint involvement as various other subgroups of juvenile idiopathic arthritis. At the beginning it often looks like early childhood oligoarthritis.

Severe iridocyclitis comes before an initial infection of the hip or the infestation of a small joint (end or middle joint) should raise suspicion of the existence of psoriatic arthritis.

Other juvenile idiopathic arthritis (ICD-10: M08.9)

Here, those subtypes of juvenile idiopathic arthritis summarized meet the criteria at either none or more of the above subgroups. Ca. 10 – 20% of patients fall into this ambiguous residual group.

Therapy

Juvenile idiopathic arthritis is a disease of unknown cause, for which there is no causal therapy. On the other hand, the majority of cases of arthritis disappear once again.