JUVENILE IDIOPATHIC ARTHRITIS[JIA]

The term arthritis refers to the presence of joint swelling and/ or pain with movement. Joint pain alone is arthralgia.

JIA refers to arthritis in a person aged less than 16 years, for a duration of more than 6 weeks, and of unknown cause.

Therefore JIA is a diagnosis of exclusion, arrived at after all other possible known causes have been excluded.

To be excluded such as malignancies, connective tissue disorders, infections, autoinflammatory disorders, joint hypermobility syndrome, etc.

JIA is heterogenous group of diseases, divided into 7 different types, depending on the number of joints involved, the presence of systemic symptoms, and the presence/ absence of rheumatoid factor.

If not recognized and treated in time, arthritis leads to permanent deformities and associated disability and poor health related quality of life. Therefore, should you suspect arthritis in those under age 16 years, get them to be seen by a rheumatologist, or pediatrician/physician. 

SYSTEMIC  JIA

Systemic type of JIA usually begins in early childhood, mostly ages 0 to 5 years, but can occur at any age up to 16 years. Another name for it is stills disease, and when it first occurs at age beyond 16 years it is called adult onset stills disease.

It is characterized by the presence of features of systemic inflammation such as persistent daily spikes of high fever, usually 39 degrees centigrade and above. Other features include a fleeting pink skin rash, myalgia, sore throat, arthralgia/arthritis, enlarged liver and spleen, enlarged lymph nodes, and serositis[ inflammation of membranes covering the heart, the lungs and peritoneum].Serositis may be accompanied by collection of variable amounts of fluid around these organs that may be life threatening.

Generally, there are three clinical disease course patterns so far recognized in systemic JIA. These are monophasic, polycyclic, and persistent patterns. In the monophasic type the disease occurs as a one off phenomenon, it is recurrent attacks with resolutions in between in polycyclic course, and there is no complete resolution of disease from the onset/first attack in persistent course.

Chronic systemic inflammation may also lead to accumulation of a substance called amyloid in various internal organs including the kidney, the liver, gastrointestinal tract, and the heart, this may lead to failure of the involved organs. 

Mesenteric adenitis can be painful, and at times can be misdiagnosed as acute abdomen leading to inappropriate surgical interventions!!

The other life threatening  complication of this disease is Macrophage activation syndrome which requires emergency management in an ICU setting.

 UVEITIS IN JIA

 JIA is the commonest cause of this disease in children, most commonly pre-school age. It refers to inflammation inside of the eye, which can be anterior/front, intermediate/middle or posterior/at the back. The most common presentation in JIA is anterior uveitis, followed by intermediate. Pan-uveitis [ front through to back] also occurs.

If not recognized and treated early leads to complications such as cataract and glaucoma. Children diagnosed with JIA must therefore be reviewed by an ophthalmologist at baseline, and regularly thereafter. Uveitis is however rare in systemic JIA.