Rheumatic diseases are not limited to adults, but can also affect children and adolescents. One of the more common types of rheumatic diseases in children is called juvenile idiopathic arthritis. According to foreign studies, it affects 1 in 1,000 children. It is generally accepted that a child with one or more arthritis lasting more than 6 weeks, excluding other causes (such as infection or trauma), is said to have juvenile idiopathic arthritis. The disease is called juvenile rheumatoid arthritis in the United States and chronic arthritis in children in the United Kingdom and Europe.
Juvenile idiopathic arthritis is a common connective tissue disease of childhood, limited to those who develop it before the age of 16 years, with two peak ages of onset: 2 to 3 years and 9 to 12 years.
Etiology
The causes of juvenile idiopathic arthritis are not fully understood and may be related to a variety of factors such as infection, immunity, and genetics.
Infectious factors Although not yet confirmed, it is possible that infectious factors may be responsible for the development of the disease. It has long been found that the disease has a high incidence in spring and summer. These pathogens include bacteria, mycoplasma and viruses.
2, immune factors Abnormal immune regulation is thought to be an important part of the pathogenesis of juvenile idiopathic arthritis.
3, Genetic factors HLA-DR4 has been recognized to be associated with juvenile idiopathic arthritis. Oligoarticular type I juvenile idiopathic arthritis with antinuclear antibody positivity and chronic iridocyclitis is thought to be associated with HLA-DR8, HLA-DR6 and HLA-DR5.
Clinical manifestations
The clinical presentation of juvenile idiopathic arthritis is complex, with systemic manifestations in addition to joint symptoms. According to the form of onset, clinical course and prognosis, it can be divided into the following 3 types, but with the progression of the disease, the types can be transformed among themselves.
(I) Systemic type
The systemic form of juvenile idiopathic arthritis, also known as Still’s disease, can occur at any age before 16 years of age, with no significant gender differences. The clinical manifestations include fever, with a chilled fever being the hallmark of this type, and a daily temperature difference of about 3 degrees C. The child is very ill with fever, but plays as usual after the fever subsides. In addition, about 95% of the children develop a rash, which is a light red spot or ring-shaped erythema. It can be seen anywhere on the body and may be pruritic. The rash appears when the fever is high and disappears when the fever subsides, leaving no trace. About 85% of cases have enlarged liver, spleen and lymph nodes. Other symptoms may occasionally include central nervous system symptoms, such as convulsions, behavioral abnormalities and EEG abnormalities. Long-term recurrent disease may result in developmental delay.
(B) Polyarthritis type
Polyarthritis is a condition in which the patient has five or more joints in the first six months of life.
This type usually starts with large joints (such as ankle, knee, wrist and elbow joints) and is often symmetrical in onset. The joints are swollen and painful, but not red. As the disease progresses, small joint lesions gradually appear; chronic inflammation of the joints may lead to muscle atrophy around the joints and gooseneck-like deformities of the hand joints. The lesion invades the temporomandibular joint and may cause difficulty in opening the mouth, and young children may complain of ear pain. In the advanced stage of the disease, the diseased joint eventually becomes ankylosed and deformed, and the muscles near the joint atrophy, resulting in motor dysfunction or even loss of function. In addition, this type may have systemic symptoms, but they are not as severe as those of the systemic type. Rheumatoid nodules may appear in a few children with this type of disease.
(C) Oligoarthritis type
The oligoarticular type refers to those with ≤4 joints in the first 6 months of disease onset. Mostly asymmetric large joint invasion, ankle, knee and other large joints of the lower extremities are often the preferred site according to the clinical performance and prognosis, can be divided into 2 subtypes.
1.Less joint type I
The proportion of this type is relatively low in children in China, and is more common in young girls, with recurrent chronic arthritis, but not serious and less disabling. Sacroiliac arthritis does not usually occur. Unilateral or bilateral chronic iridocyclitis occurs in about half. In later stages, permanent visual impairment or even blindness may result from posterior iris adhesions, secondary cataracts and glaucoma. This type has mild systemic symptoms and generally has a good prognosis.
2. Oligoarthritis type II
Boys are the majority, the age of onset is often older than 8 years, and the lesions often invade the knee, ankle and other large joints of the lower limbs. The early stage does not affect the sacroiliac joint, but some cases may lead to sacroiliac arthritis and tendon attachment lesions at a later stage. Self-limiting iridocyclitis occurs in some patients, and permanent visual impairment is rare. There are few systemic symptoms. In this type, some children progress to ankylosing spondylitis after the age of 16 years.
In general, juvenile idiopathic arthritis has a variety of manifestations, with the younger the age of onset, the more severe the systemic symptoms and the less severe the arthritic lesions; in children older than 7 years of age, most of the symptoms are mainly arthritic and the systemic symptoms are mild. If you find any of these suspicious symptoms, you should seek medical attention so that you can make a good diagnosis and treat the disease as soon as possible.