Juvenile Idiopathic Arthritis: Everything You Need to Know

Juvenile idiopathic arthritis is one of the most common rheumatic diseases during the first years of life. Find out everything you need to know about it.

Juvenile idiopathic arthritis is a chronic rheumatic manifestation that affects children and young people. It’s not a disease in itself, but rather a group of several conditions with different characteristics, symptoms, evolutions, and treatments.

According to the International League of Rheumatology Associations (ILAR), this condition is defined as “a type of arthritis that begins before the age of 16 and persists for at least 6 continuous weeks”.

Its prevalence is very uneven, although the Pediatric Orthopedic Society of North America (POSNA) estimates that between 2 and 20 cases are reported per 100,000 inhabitants. Let’s see what experts know about this disease.

The causes of Juvenile Idiopathic Arthritis

As the name suggests, an exact etiology for juvenile idiopathic arthritis hasn’t been found. However, it’s known to be an autoimmune disease. For reasons still unknown, the body itself attacks the linings of the joints (synovium). This causes inflammation and leads to other complications if it’s not treated in a timely manner.

Experts believe that genetic predisposition can increase the chances of developing it, as well as exposure to certain environmental factors. Despite this, and as the Arthritis Foundation points out, so far, researchers haven’t found toxins, foods, allergies, or dietary behaviors that are related to it.

For all these reasons, it’s a disease that can’t be prevented. Initially, it was known as juvenile chronic arthritis or juvenile rheumatoid arthritis. Today, the use of these names is avoided, since more exact divisions have been established according to symptoms and evolution. So, let’s look at what progress there is in this regard.

The types of Juvenile Idiopathic Arthritis

There are many types of Juvenile Idiopathic Arthritis (hereinafter JIA). As understanding of the processes leading to its development improves, researchers refine the classification used to catalog clinical manifestations. Based on information from Johns Hopkins Medicine, and leaving some nuances aside, we can mention the following types:

Systemic JIA

This is also known as Still’s disease. It’s the most serious form of the disease, although fortunately, it’s also the least frequent, as Stanford Health Care indicates. It can affect more than one joint, as well as cause complications in the body’s organs. Those it affects the most are the heart, liver, and lymph nodes.

Oligoarticular JIA

According to the Spanish Society of Pediatric Rheumatology (SERPE), the oligoarticular form is the most common in children and young people. It is divided into persistent and extended. In the first case, the damage occurs in four or fewer joints, while in the second, the number exceeds that amount. It’s more common in the lower limbs, especially the knee.

Polyarticular JIA

The polyarticular variant is diagnosed when the damage is focused on 5 or more joints. Researchers have found that it’s most common between the first and third years of age. After this, it enters a “latent state”, only to manifest itself again between the ages of 9 and 14. It’s more common in girls than in boys.

Psoriatic arthritis

Although there’s controversy regarding its classification, studies indicate that this type is characterized by arthritis accompanied by psoriatic eruptions. This variant is also diagnosed when the patient meets two of the following criteria:

• Onycholysis (separation of a nail from your nail bed)
• Dactylitis (inflammation of the fingers)
• Having a first-degree relative with psoriasis

Skin symptoms are most common around the joints, although they can also appear on the scalp, navel, and perineum.

Enthesitis-related JIA

In this case, the patient develops arthritis and enthesitis in the same episode. It’s more common in males after 6 years of age and, according to the evidence, it can also occur in the company of acute anterior uveitis (inflammation of one of the layers of the eyeball). It usually occurs in the upper extremities, such as the knees and ankle.

Undifferentiated arthritis

Other manifestations that don’t fit with the aforementioned types are known as undifferentiated arthritis. This term is also used to describe episodes that share two or more symptoms from different categories.

It’s a difficult variant to treat, so some researchers endorse early therapies to discover which regimen achieves better results.

The symptoms of juvenile idiopathic arthritis

The symptoms of juvenile idiopathic arthritis vary according to each variant. Even among these, patients experience different signs, which can be chronic or mild. It’s very common for symptoms to manifest themselves in flare-ups, after which a period of temporary remission can take place.

In any case, we can mention the following as the most common signs of the disease:

• Swelling in the joints
• Pain and stiffness in the affected area
• Limitations when trying to move the joint at different angles
• Increased temperature in the affected area
• Fatigue
• Slow growth
• Loss of appetite
• Weightloss
• Swelling of the lymph nodes
• Rashes
• Fever

Only in chronic cases, which are rare, will young people experience organ damage. To avoid this, it’s very important to be attentive to the symptoms in order to seek medical assistance and proceed with diagnosis.

Diagnosing of juvenile idiopathic arthritis

As the American College of Rheumatology reminds us, the diagnosis of JIA is complex. First of all, because the inflammation is often very mild, so much so that those affected don’t report it to their parents. In turn, there’s no specific test to detect variants of the disease. The sum of both factors obscures the diagnosis of juvenile arthritis.

In any case, the criteria mentioned at the beginning will always be taken into account: The process must start before the age of 16 and manifest itself over 6 continuous weeks (at least).

With this in mind, in addition to the consideration and evaluation of the child’s symptoms, the rheumatologist may suspect that you’re dealing with some type of JIA. To confirm their suspicions, they’ll indicate the following laboratory tests:

• Antinuclear antibodies
• Complete blood count
• Complement test
• Erythrocyte sedimentation rate
• C-reactive protein
• Hematocrit
• Creatinine
• Rheumatoid factor
• White blood cell count

Imaging tests such as CT scans, X-rays, MRIs, and ultrasounds can also be done. If the specialist considers it necessary, a urine test and a joint aspiration will also be performed.

Most of these are used to rule out other explanations for the symptoms. For example, Lyme disease, lupus, and some bone disorders may share some of the signs. Once these and other conditions are ruled out, the specialist will be able to confirm the presence of a variant and thus begin treatment.

The treatment of juvenile idiopathic arthritis

The therapy used by the specialist to control the symptoms and improve the prognosis of the disease depends on several factors. Age of diagnosis, the variant in question, the severity of symptoms, and possible risks of complications are the criteria that serve as the basis for treatment.

Researchers agree that disease-modifying antirheumatic drugs are the first available option. These have been shown to be safe for this age group and allow the progression to stop in a couple of weeks. The most widely used is methotrexate, although sulfasalazine and leflunomide can also be helpful.

Other alternatives that can be used are the following:

• Non-steroidal anti-inflammatory drugs
• Corticosteroids
• Biological drugs

Focused massage, physical therapy, nutritional counseling, regular exercise, maintaining or losing weight, using hot or cold compresses, and rest also improve symptoms. The choice depends on the variant, so it’s best to seek medical assistance as soon as the first symptoms are experienced.