Juvenile rheumatoid arthritis

Juvenile Rheumatoid Arthritis


BASIC INFORMATION
Juvenile rheumatoid arthritis is arthritis beginning before the age of 16 yr. and consists of several conditions characterized by chronic synovitis and joint swelling, pain, and tenderness. The disease can also produce extra-articular signs and symptoms that involve the skin, heart, lungs, liver, spleen, and eyes. Major types of JRA include systemic (Still's disease or acute febrile type), polyarticular, and pauciarticular.
SYNONYMS
Still’s disease
Juvenile chronic arthritis
Juvenile polyarthritis
CAUSES
Researchers continue to probe for the causes of JRA. Various findings suggest links to genetic factors or to an abnormal immune response. Viral or bacterial (particularly streptococcal) infection, trauma, and emotional stress may be precipitating factors, but their exact relation to the disease remains unclear.
EPIDEMIOLOGY & DEMOGRAPHICS
PREVALENCE (IN U.S.): 250,000 to 300,000 cases
PREVALENT SEX: Female:male ratio of 2:1
PREVALENT AGE: Two peak incidences, between ages of 1 and 3 yr and ages 8 and 12 yr.
PHYSICAL FINDINGS & CLINICAL PRESENTATION
Usually one of three types:
Juvenile rheumatoid arthritis
SYSTEMIC OR ACUTE FEBRILE JUVENILE RHEUMATOID ARTHRITIS (20% OF CASES):
• Characterized by extraarticular manifestations, especially spiking fevers and a typical rash that frequently appears in the evening and may be elicited by gently scratching the skin in susceptible areas (Koebner’s phenomenon).
• Possible splenomegaly, generalized lymphadenopathy, pericarditis, and myocarditis.
• Often, minimal articular findings overshadowed by systemic symptoms.
WORKUP
Initial laboratory and imaging studies are often nonspecific in children with rheumatoid arthritis.
LABORATORY TESTS
• Increased ESR
• Low-grade anemia
• Very high peripheral WBC count
• Rheumatoid factor: rarely demonstrable in the serum of children
• Antinuclear antibodies: often found in children with ocular complications
IMAGING STUDIES
• Roentgenographic findings are similar to those in adult, with soft tissue swelling and osteoporosis early in the disease.
• Joint destruction is less frequent.
• Bony erosion and cyst formation may be present as a result of synovial hypertrophy.
TREATMENT
Successful JRA management usually calls for antiinflammatory drugs, physical therapy, carefully planned nutrition and exercise, and regular ophthalmologic examinations. Both the child and the parents must be involved in therapy.
     Aspirin is the initial drug of choice. Dosage is based on the child's weight. Additional nonsteroidal anti-inflammatory drugs (NSAIDs) may be used. If they prove ineffective, gold salts, hydroxychloroquine, and penicillamine can be tried. Because of adverse effects, corticosteroids are reserved for treating systemic disorders (such as pericarditis and iritis) that resist treatment with NSAIDs. Corticosteroids and mydriatic drugs are commonly prescribed for iridocyclitis. Investigational drug therapy includes low-dose cytotoxic agents, such as methotrexate.
     Physical therapy promotes regular exercise to maintain joint mobility and muscle strength, thereby preventing contractures, deformity, and disability. Good posture, gait training, and joint protection are also beneficial. Splints help reduce pain, prevent contractures, and maintain correct joint alignment. Applying heat during passive exercises (for example, by whirlpool, paraffin, or hot packs) is beneficial.
     Surgery is usually limited to soft-tissue releases to improve mobility. Joint replacement is delayed until the child matures physically and can tolerate vigorous rehabilitation.
NONPHARMACOLOGIC THERAPY
Proper management requires close cooperation among primary physician, therapist, rheumatologist, and orthopedist.
• Rest
• Physical and occupational therapy
• Patient and family education
• Proper diet and weight maintenance
ACUTE GENERAL Rx
• Aspirin (stopped during childhood viral illnesses to avoid Reye’s syndrome)
• Other NSAIDs
• DMARDs and biologic response modifiers (BMRs)
• Intraarticular steroids
• Systemic corticosteroids
DISPOSITION
• Complete remission occurs in the majority of patients and may occur at any age.
• 70% to 85% of children regain normal function.
• Mortality rate is 2%.
• Children with a protracted systemic phase of the disease are most at risk for developing serious intercurrent infection and potentially fatal amyloidosis.
• Myocarditis may develop in the systemic form.
• Blindness is the most serious complication of the pauciarticular form; joint deformity is the most serious problem of polyarticular disease.
PAUCIARTICULAR OR OLIGOARTICULAR FORM (50% OF CASES):
• Involves fewer than five joints.
• Usually involves the larger joints, such as the knees, elbows, and ankles.
• Systemic features often minimal, and only one to three joints usually involved.
• Rarely causes impairment but chronic iridocyclitis develops in approximately 30% of cases with this form, and permanent loss of vision will develop in a high percentage of these patients.
• Accelerated growth of the affected limb from chronic hyperemia possibly resulting in a temporary leg length discrepancy that is eventually equalized in most cases on control of the inflammation.
POLYARTICULAR JUVENILE RHEUMATOID ARTHRITIS (30% OF CASES):
• Involves five or more joints.
• Resembles the adult disease in its symmetric involvement of the small joints of the hands and feet.
• Cervical spine involvement common and may produce marked loss of motion.
• Early closure of the ossification centers of the mandible, often producing a markedly receding chin, a characteristic of this form.
• Systemic manifestations similar to the febrile variety but not as dramatic.
ETIOLOGY
Unknown. There is increasing evidence that the inflammation and destruction of bone and cartilage that occurs in many rheumatic diseases are the result of the activation, by some unknown mechanism, of proinflammatory cells that infiltrate the synovium. These cells, in turn, release various substances, such as cytokines and tumor necrosis factor (TNF) alpha, which subsequently cause the pathologic changes typical of this group of diseases. Many of the newer therapeutic agents are directed at the suppression of these final mediators of inflammation.
DIAGNOSIS
Complete blood count usually shows decreased serum hemoglobin levels and increased neutrophil (neutrophilia) and platelet (thrombocytosis) levels. Other blood test findings include an elevated erythrocyte sedimentation rate and elevated C-reactive protein, serum haptoglobin, immunoglobulin, and C3 complement levels. Antinuclear antibody test results may be positive in patients with polyarticular JRA and in those with pauciarticular JRA with chronic iridocyclitis. Rheumatoid factor (RF) appears in about 15% of patients with JRA. In contrast, about 85% of patients with rheumatoid arthritis test positive for RF. Patients with polyarticular JRA may test positive for RF. The presence of human leukocyte antigen (HLA)-B27 in blood tests may forecast later development of ankylosing spondylitis. X-ray studies demonstrate early structural changes associated with JRA. These include soft-tissue swelling, effusion, and periostitis in affected joints. Later evidence includes osteoporosis and accelerated bone growth followed by subchondral erosions, joint space narrowing, bone destruction, and fusion.
DIFFERENTIAL DIAGNOSIS
• Infectious causes of fever
• SLE
• Rheumatic fever
• Drug reaction
• Serum sickness
• “Viral arthritis”
• Lyme arthritis
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