32: Juvenile Idiopathic Arthritis

Question 1

Juvenile idiopathic arthritis (JIA) epidemiology

Answer 1

• affects approx 1 in every 1000 children
• represents the most common cause of chronic joint pain in the paediatric population.

Question 2

JIA presentation

Answer 2

Systemic signs usually first:
- fevers
- generalised malaise
- salmon pink rash

Joint involvement:
- joint pain
- joint swelling
- morning stiffness
- limited range of motion

Question 3

list some investigations which can aid in the diagnosis of JIA and exclusion of other conditions

Answer 3

• Blood tests: FBC, ESR, CRP, antinuclear antibodies (ANA), rheumatoid factor (RF)
• Imaging: US or MRI of affected joints may reveal synovial hypertrophy, effusion or bone erosion.
• Joint aspiration: to rule out infection or malignancy.

Question 4

JIA medical management

Answer 4

• NSAIDs: primarily for symptom control
• steroids: can be administered either intra-articular or orally for controlling inflammation.
• steroid-sparing agents: methotrexate or biological agents such as TNF-alpha inhibitors may be used to minimise long-term steroid use.
• IL-1 receptor anatogonist (Anakira) in refractory systemic arthritis
• IL-6 anatgonist (Toclilizumab) for refractory systemic disease

Question 5

list some potential complications of JIA

Answer 5

• flexion contractures: may require physio and splinting
• joint destruction: may necessitate prostheses at a young age
• growth failure: can occur as a result of chronic disease and steroid use
• anterior uveitis: this can lead to visual impairment if not detected and treated early

Question 6

JIA classification criteria

Answer 6

1. age of onset < 16 years
2. duration of disease > 4 weeks
3. presence of arthritis > joint swelling or 2 of the following: painful or limited joint motion, tenderness, warmth.

Question 7

list the 3 major subtypes of JIA

Answer 7

• oligoarticular (55%), 4 or less joints
• polyarticular (25%), 5 or more joints
• systemic onset (20%)

Question 8

polyarticular JIA presentation

- ve vs +ve

Answer 8

RF -ve:
- constitutional manifestations (low grade fever, malaise)
- hepato-splenomegaly
- mild anaemia
- growth abnormalities
- uveitis is rare

RF +ve:
- constitutional manifestations,
- anaemia
- nodules