for massive pericarditis causing compromise of cardiac output, or if significant symptoms persist despite therapy with NSAIDs In the presence of tamponade or progressive deterioration, pericardiocentesis provides temporary relief, whereas antiinflammatory medications are used to prevent re-accumulation of fluid Pulmonary Emergencies Pleural effusions are a recognized manifestation of sJIA ( Fig 101.9 ) Occasionally, pleural fluid collections may be massive, resulting in respiratory distress Other pleuropulmonary complications include pneumonitis, diffuse interstitial disease, lymphoid bronchiolitis, and pulmonary arteritis In the absence of the need for thoracentesis for diagnostic or therapeutic purposes, treatment is aimed at the underlying disease process, primarily involving control of inflammation with NSAIDs, corticosteroids, or anakinra Children with pleural effusions often require admission in order to address the overall severity of systemic features of the disease FIGURE 101.9 Pericardial and pleural effusions in a child with systemic onset juvenile idiopathic arthritis Iridocyclitis Iridocyclitis (inflammation of the iris and ciliary body) occurs in approximately 10% to 20% of all children with JIA This can be of acute or chronic onset The chronic type of iridocyclitis occurs primarily in young children with oligoarticular JIA, especially girls with oligoarthritis and a positive ANA In contrast, acute iridocyclitis occurs most often in older boys with oligoarticular disease Acute iridocyclitis is characterized by sudden onset of redness, tearing, pain, and photophobia, and urgent management may be required to preserve vision Immediate consultation with an ophthalmologist is essential The usual emergent treatment includes topical corticosteroids and mydriatics Flare of a Single Joint in a Patient with JIA In a patient known to have JIA and receiving anti-inflammatory medication, acute swelling with pain and limitation of range of movement of a single joint raises a common management problem Potential causes of such an acute monoarthritis include a flare of JIA versus septic arthritis or Lyme arthritis, and careful attention to physical examination and historical features are essential to avoid misdiagnosis Physical findings characteristic of infection of a joint are fever, extreme pain, tenderness, erythema, and warmth over the joint The affected joints of JIA, while often swollen, warm, and stiff, are rarely red With infection, there is usually pronounced splinting of an infected joint due to pain; the slightest movement may cause muscle spasm In contrast, some range of motion is usually possible even with severely inflamed joints of JIA If the patient is taking an immunosuppressive medication, physical findings of inflammation and/or infection may be masked If infection cannot be excluded with confidence, joint fluid must be aspirated, and the fluid sent for cell count, Gram stain, and culture Synovial fluid is bacteriostatic and some fastidious organisms, such as Kingella , may be particularly difficult to culture, so joint fluid samples should be inoculated into blood culture bottles to optimize sensitivity If there is any doubt about the diagnosis, it is best to also obtain a blood culture (which increases diagnostic yield, as the organisms causing septic arthritis are generally spread hematogenously) and then to initiate treatment for septic arthritis For the acute swelling and pain in a single joint caused by a JIA flare, resting the involved extremity for to days may be adequate After infection has been excluded, injection of the joint with a topical steroid preparation such as triamcinolone hexacetonide (1 mg/kg, maximum 40 to 60 mg) may provide rapid and sustained relief If multiple joints are involved during a flare, treatment with systemic agents from NSAIDs to corticosteroids may be necessary, as may escalation of the baseline antiarthritis regimen for severe or persistently active arthritis Ruptured Popliteal Cyst There are six bursae around the knee joint Of these, the gastrocnemius semimembranosus bursa is the one that most often communicates with the synovial space Consequently, in the presence of effusion in the knee joint, fluid may enter the bursa and produce a popliteal cyst (Baker cyst) Patients with popliteal cysts have a palpable and visible enlargement in the popliteal area, best seen while the patient is standing with knees extended Rupture of a popliteal cyst with drainage of fluid into the calf muscles may present as an emergency Affected patients complain of sudden pain in the calf associated with swelling in the leg On physical examination they have induration, erythema, warmth, and tenderness of the calf, as well as ankle edema An effusion in the knee joint and evidence of synovial thickening are often present Homan sign may be positive, but other signs of venous thrombosis, including palpable venous cords, dilation of collateral veins, or arterial spasm, are usually absent Differentiation of a ruptured popliteal cyst from thrombophlebitis may be difficult, though the latter are very rare in otherwise healthy children, and the former relatively common in children with arthritis Elevated D -dimers and other evidence of a consumptive coagulopathy characterize venous thrombosis, while most children with JIA not have such abnormalities (with the exception of patients with sJIA experiencing MAS) Ultimately, ultrasound or MRI may be needed to establish the diagnosis Intra-articular administration of steroids (triamcinolone hexacetonide, mg/kg) is the recommended initial treatment for a ruptured Baker cyst If there is an inadequate response or if the syndrome is chronic, surgical excision of the cyst may be necessary Cervical Spine Involvement This complication usually is seen in children with established severe polyarticular JIA Although cervical spine involvement is known to occur in 30% to 50% of patients with JIA, subluxation of the atlantoaxial (AA) joint or the lower cervical spine is less common in children than adults Clinical evidence of pressure on the spinal cord is seen in 23% to 65% of adults with radiologic evidence of AA subluxation Similar data are not available for children Neck stiffness that is worst in the morning is the most common symptom of cervical spine involvement in JIA Occasionally, torticollis may be the presenting manifestation of cervical arthritis Severe pain in the neck and referred pain over the occipital and retro-orbital areas also may occur The pain has a dull, aching quality and is often aggravated by neck movement On physical examination, torticollis and/or loss of lordosis of the cervical spine, as well as limitation of range or movement of the neck, are the typical findings Paresthesia of the fingers is the most common symptom of spinal cord compression Weakness of the arms and legs and inability to control the bladder or bowels are other complaints that should suggest spinal cord compression During the initial stages, exaggerated deep tendon reflexes and an extensor plantar reflex are noted Chronic myelopathy results in muscle atrophy and loss of deep tendon reflexes Lateral radiographs of the neck in flexion and in extension are required for complete evaluation of the cervical spine The patient should be asked to actively and slowly flex and extend the neck to tolerance without discomfort; care should be taken not to force these movements On some occasions, CT or MRI may be indicated The distance between the anterior surface of the odontoid and the posterior surface of the anterior arch of atlas when measured in a lateral film with neck in flexion is usually mm or less In the presence of AA subluxation, this may be as wide as 10 to 12 mm ( Fig 101.10 ) Other radiologic abnormalities characteristic of cervical spine involvement in JIA include loss of curvature, osteoporosis, erosions and sclerosis of joints, disc-space narrowing, and altered height-to-width ratio of the vertebral bodies Although most children with AA subluxation not have evidence of spinal cord compression, the physician must be wary of its occurrence with excessive movement, as occurs during endotracheal intubation Regular use of a light plastic cervical collar is often all that is required to relieve pain and prevent excessive anterior flexion, particularly during automobile rides In the presence of spinal cord compression, surgical stabilization may be required ... extended Rupture of a popliteal cyst with drainage of fluid into the calf muscles may present as an emergency Affected patients complain of sudden pain in the calf associated with swelling in the