Read Rosen & Barkin's 5-Minute Emergency Medicine Consult Online

Authors: Jeffrey J. Schaider,Adam Z. Barkin,Roger M. Barkin,Philip Shayne,Richard E. Wolfe,Stephen R. Hayden,Peter Rosen

Tags: #Medical, #Emergency Medicine

Rosen & Barkin's 5-Minute Emergency Medicine Consult (73 page)

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ETIOLOGY

Believed to be an autoimmune disease triggered by an unknown environmental trigger in a genetically susceptible host

DIAGNOSIS
Subtypes

Systemic onset:
- 10% of cases, girls = boys
- Associated fever and arthritis:
  - Fever: Diurnal (>39°C) of >2 wk duration, child looks ill during temperature spike
  - Arthritis: May involve any number of joints and may appear only weeks to months after onset of fever
- In addition there must be 1 of the following:
  - Maculopapular, salmon-colored rash on trunk and axillae
  - Lymphadenopathy
  - Hepatosplenomegaly
  - Serositis
- Most acute, ill appearing of subtypes
- Destructive arthritis >50%

ALERT

Systemic onset JIA patients are at risk for macrophage activation syndrome (MAS).
MAS is a proliferation of macrophages causing a DIC-like picture with resultant fever, mucosal bleeding, neurologic changes and multisystem failure.
ESR may be normal in active MAS
MAS mortality is 8–22%.
Pauciarticular:
- 50% of cases of IJA
- 80% girls, peak incidence 2–4 yr olds
- Insidious onset and child appears healthy
- ≤4 joints involved at 6 mo:
  - Involves larger joints, (89% knee)
    hip rarely affected
  - Joints swollen, mildly tender, with decreased range of motion (ROM), possible leg-length discrepancy
- Uveitis in about 20%; no other systemic signs
- Subset termed
  extended
  pauciarticular progresses to greater joint involvement after 6 mo and has worse prognosis
Polyarticular:
- 10–30% of cases, girls > boys, bimodal peaks: 2–5 and 10–14 yr
- >4 joints involved at 6 mo:
  - Arthritis often symmetrical, small or large joints—commonly knees, wrists, and ankles
  - Decreased ROM of cervical and lumbar spine and temporomandibular joint (TMJ)
- Systemic involvement rare except for fatigue and anemia
- Older girls with RF
  ⁺often go on to develop typical adult rheumatoid arthritis (RA) and are placed in a separate subtype.
Psoriatic:
- Arthritis; asymmetric large joints of lower extremities and back
- Psoriatic rash in patient or 2 of the following: Dactylitis, nail pitting, psoriatic rash in 1st-degree relative
- Enthesitis-related (
  enthesis
  means pain at the insertion of a muscle or tendon)
- Arthritis; asymmetric large joints of lower extremities
- Boys > girls, age usually >6 yr
- Sacroiliac (SI) joint pain
- Limited flexion of lumbar spine
- Uveitis
- Often FH
Otherwise unclassified:
- Arthritis not fitting into any distinct category

History

Findings based on specific subtype
Classic presentation is insidious arthritis, worse in AM and with periods of immobility, improved with ROM.
New-onset systemic subtype most likely to use ED because they appear acutely ill, whereas other subtypes have a more insidious onset.

ALERT

Child with severe pain and red-hot joint probably does not have new-onset JIA.
Rapid onset of polyarticular joint involvement is atypical for JIA; infectious or reactive cause of arthritis should be ruled out.
Beware of occult infection in patients on immunosuppressants.

Physical-Exam

Determine if child is systemically ill: Search for fever, rash, or other nonarthritic involvement.
Do careful joint evaluation, documenting the number of joints involved and noting whether they are red, warm, and swollen or have limited ROM.

ESSENTIAL WORKUP

Rule out septic joint and malignant bone tumor.
Rule out other identifiable causes of joint inflammation.
Rule out complications from long-term drug therapy.

DIAGNOSIS TESTS & NTERPRETATION
Lab

CBC, ESR; if ill appearance, add blood cultures
Other labs if suspicious of specific subtype: rheumatoid factor (RF), antinuclear antibodies (ANA), HLA-B27, LFTs:
- Systemic—ESR often elevated, leukocytosis, thrombocytosis, anemia, minor AST/ALT elevations, positive RF or ANA rarely seen, MAS may be associated with elevated LFTs and abnormal clotting factors but will often have normal ESR
- Pauciarticular—common to have positive ANA in young girls; other labs usually normal; if anemic or elevated ESR, are probably misclassified or pauciarticular extended subtype
- Polyarticular—may be anemic; if positive RF more likely to go on to adult RA, ESR may be elevated
- Enthesitis—more likely positive HLA; presence of positive RF or positive ANA specifically excludes enthesitis subtype
- Psoriatic arthritis—usually seronegative RF
Unfortunately, RF and ESR may also be elevated in acute infection unrelated to JIA.

ALERT

Consider adding Lyme titer if new joint swelling in endemic area.

Imaging

Joint radiograph:
- Early presentation: Soft tissue swelling, joint effusion
- Late presentation: Osteoporosis, joint destruction, early growth plate closure
Ultrasound:
- Evaluate for small effusion, especially if tap considered.

Diagnostic Procedures/Surgery

Arthrocentesis if concern for septic arthritis: 5,000–8,000 WBC/mm
³with negative Gram stain and culture typical for JIA

DIFFERENTIAL DIAGNOSIS

Trauma
Infection:
- Septic arthritis, viral infection (especially parvovirus), Lyme disease, rheumatic fever, tuberculosis, subacute endocarditis, malaria,
  Neisseria gonorrhoeae
  infection
Other rheumatic/connective tissue diseases:
- Systemic lupus erythematosus, polyarteritis nodosa, Henoch–Schönlein purpura, sarcoid
- Legg–Calvé–Perthes disease/slipped capital femoral epiphysis
Neoplasm:
- Be suspicious of neoplasm in a severely uncomfortable child with midshaft bone pain.
Hematologic disease:
- Sickle cell disease, hemophilia
Drug reactions

TREATMENT
INITIAL STABILIZATION/THERAPY

Toxic-appearing children: IV access, O
₂

ED TREATMENT/PROCEDURES

ED treatment is directed toward ruling out a septic joint and other causes of acute arthritis
If the diagnosis of JIA is already established and the child presents with an acute flare, a treatment plan/medication adjustment should be coordinated with the child’s rheumatologist.

MEDICATION

Medication in children with JIA is geared toward eliminating clinical signs of active disease, maximizing joint function, and preserving growth. (Chronic inflammation can make affected limb slightly longer.)
Efficacy depends on JIA subtype and disease severity.
Most pauciarticular JIA responds to NSAIDs and joint injections; polyarticular and systemic JIA usually require disease-modifying antirheumatic drug (DMARD) therapy and/or biological agents.
Antibiotics are indicated only if the joint is infected.

ALERT

As early aggressive therapy may prevent some of the long-term complications of JIA, it is now common for children to be placed on DMARDS and biological agents early in the disease course. These medications have serious potential side effects, including:

Immunosuppression
Decreased vaccine response (live vaccinations are contraindicated)
Increased potential for malignancy
NSAIDs:
- Responsiveness differs within NSAID subtype
- Used alone in mild JIA subtype or with other medications
- Ibuprofen: 30–45 mg/kg divided TID–QID
- Naproxen: 10–20 mg/kg divided BID; maximum daily dose 1,000 mg
- Side effects: Gastritis, hepatitis, renal, headache, dermatitis
- Intra-articular steroids: Triamcinolone hexacetonide: 1 mL/mg of 20 mg/mL solution
- Often provide long-term (6–18 mo) relief
DMARDs:
- Include corticosteroids, methotrexate, sulfasalazine
- Corticosteroids
- Use judiciously because of long-term complications, but high-dose pulse therapy may be needed in acute attack.
- Prednisone: 0.5–2 mg/kg PO
- Methylprednisolone: 30 mg/kg daily IV up to 1 g for 1–5 days for high-dose pulse steroids
- Side effects: Gastritis, adrenal suppression, osteopenia, Cushing syndrome, infection
- Methotrexate: 5–15 mg/m
  ²PO/SC or IM per week
- Considered 1st-line DMARD, as most will respond
- Side effects: GI, nausea, liver toxicity, teratogenic
- Sulfasalazine: 30 mg/kg/d divided QID
- Poorly tolerated in up to 30%
- Side effects: GI, rash, anorexia
- Biological agents—engineered to target specific key cytokines, very expensive
- Tissue necrosis factor binders
Etanercept: 0.8 mg/kg SC once a week
- Adalimumab: < 30 kg: 20 mg, > 30 kg: 40 mg given SC administered every other week
- Side effects: Infection, injection-site reactions, inhibit T-cell activation
- Abatacept: 10 mg/kg infusion q4wk
- Side effects: Infusion reaction, HA, cough, nausea, infection
Non-FDA–approved therapies:
Remicade, rituximab, anakira, leflunomide IL-1 and IL-6 blockers
Stem cell transplants are used rarely for severe cases unresponsive to medical treatment:
- Treatment for MAS is nonstandardized but may include high-dose steroids, cyclosporine, cyclophosphamide, or intravenous immunoglobulin