Simple Explanation of Juvenile Rhumatoid Arthritis (JRA) for USMLE. Focusing on the Signs and Symptoms, clinical presentaiton, Diagnosis, Treatment and Management. In particular Oligoaruticular, Pauciarticular, Polyarticular, Systemic, Enthesitis and Psoriatic Arthritis.
Juvenile Rheumatoid Arthritis is classified into 5 categories. The first category is oligoarticular or Pauci articular JA. Then there is polyarticular Juvenile Rheumatoid Arthritis. This is divided into subgroups depending on Rheumatoid Factor. Rhematoid Factor positive is also referred to as Early Onset Adult Rheumatoid Arthritis. Systemic Rheumatoid Arthritis, Enthesitis is not necessarily the joints but actually the tendon. Finally there is Psoriatic.
Most common is oligoartiruclar (40%). RF postivie is more than RF-. Systemic 10-20% and the other is very rare.
Oligoarticular Rhematoid Arthritis is when there is less than 4 joints within 6 months. If there is move than 4 joints, but takes longer than 6 months, then this is known as extended. This tends to be slightly more severe.
Polyarticular is have more than 5 joints involved within 6 months. Systemic there is more than 5 jointsh within 6 months and there are systemic symptoms.
Enthesitis is related to the tendon-bone attachment. FInally Psoriatic is related to a rash.
Oligoarticular is less than 8 years, Rhematoid Factor Negative is found in 8-12 years old and Rheumatoid Factor Positive occurs in greater than 13 years old. Systemic can occur in any age group.
Joints involved in Oligarticular hte knee is the most common, also affected is the ankle. Typically associated with morning stiffness and swollen joints. Hip involvement is unusual.
Rhematoid Factor Negative Polyaritcular. Large and Small joints of hands and feets such as knee, ankles, and wrists. Temporomandivular joint and spine is also much more common joint. No HIP invovlement
Rheumatoid Factor Positive is similar to Adult Rheumatoid Arthritis so it is symettrical and very aggressive.
Systemic can be any joint.
Enthesitis there is sacroiliac and spinal pain and stiffness
Psoriatic is primarily Finger (Dactylitis)
Uveitis is a very serious and common symptom. Oligoarticular Rheumatoid Arthritis can cause Iriditis. Also Enthesitis and Psoriatic which also has Anterior Uveitis. Psoriatic is painful whereas in Oligarticular is painless. Therefore you must do slit lamp to preven blindness, cataracts, glaucoma. Treatment with glucocorticoids and mydriatics. All of these are associated with ANA Positive.
Rheumatoid Factor Negative does not have extra articular symptoms. However, in Rheumatoid Factor Positive there are classic Rheumatoid Nodules, vasculitis and lung disease and continue to adult Rheumatoid Arthritis.
Systemic Rheumatoid Arthritis is difficult to diagnose because systemic symptoms may occur months before there are any joint involvement. The most important is associated with a fever and rash that goes away when there is fever. Salmon colored, erythematous and maculopapular. Serositis (pleuritis and Pericarditis lymphadenopathy and hepatosplenomegaly). There are some lab findings such as High ESR and elevated WBC and platelets. There is anemia and Elevated LFT.
Macrophage Activating Syndrome (MAS). INcrease Macrophage, T Cell, Interferon Gamma, GM-CSF. You must rule out infection and malignancy.
In Enthesitis there must be two of the following. First there must be sacroiliac tenderness and/or spinal pain. HLA B27, Family History if there is a history of primary or secondary relative. Associated Anterior Uveitis. Greater than 8 years old and if they are a boy. The prognosis of Enthesitis is good.
Psoriatic Arthritis. Salmon colored lesion. It has a variable course with remissions and exacerbations.
Diagnostic Criteria. Firstly, 6 weeks of persistent swollen joint. Must be less than 16 years old. Diagnosis of Exclusion so you must exclude septic arthritis. No test to rule out or confirm Juvenile Rheumatoid Arthritis therefore it is difficult to diagnose.
Treatment is physiotherapy to maintain range of motion and avoid contractions. Multi-Discipline team effort of physiotherapist, social worker, orthopedic, ophthlamologist, Rheumatologist and possibly a pediatrician. Medications are NSAIDs and Intra-Articular corticosteroids and injections into joint that helps eliminate pain. Can't give for too long becuase it destroys the joint tissue.
Disease Modifying Anti-Rheumatic Drugs. Methotrexate. Biologic Agents such as etanercepts, Adalimumab, Infliximab