Case 1: Acute chorea

A previously healthy Caucasian boy, nine-and-a-half years of age, presented with a four-day history of involuntary movements of his eyes, lips and tongue, as well as of both arms and legs. The movements were uncontrollable and constant, but regressed when asleep. He experienced symptoms of dizziness and headache at the onset of the movements, but these had resolved. He had progressive difficulty ambulating, speaking and eating. There was no incontinence, change in vision, hallucinations, change in level of consciousness, aphasia or cognitive changes noted. He had no history of preceding illness or trauma. Initial physical examination revealed an afebrile boy who was awake and alert. His heart rate was 84 beats/min and blood pressure was 100/62mmHg. He was oriented to person, place and time. There was no papilledema. He exhibited no rash, mucosal ulcers, tonsillar abnormality or lymphadenopathy. The patient had a III/VI systolic murmur at the left lower sternal border. No S3 or rub were noted. Respiratory, abdominal and musculoskeletal examinations were normal. Neurological examination revealed ongoing choreiform movements of all limbs, tongue (darting) and lips. His hands alternately squeezed and released when gripping an object (milkmaid sign). The remainder of his neurological examination, including tone, power, reflexes, coordination and sensation, was normal. The patient's white blood cell count was 3.8×109/L, lymphocyte count was 1.3×109/L, hemoglobin was 113 g/L and platelet count was 211×109/L. Direct antibody (Coombs) test was positive. Toxicology screen and metabolic work-up were negative. Cerebrospinal fluid analysis revealed a white blood cell count of 9×106/L and no red blood cells. Testing for mycoplasma and herpes viruses was negative. Brain magnetic resonance imaging demonstrated a tiny focus of diffusion restriction in the white matter of the right frontal lobe. Magnetic resonance angiography and venography were normal. Chorea is an ongoing, random-appearing sequence of one or more discrete involuntary movements. It is worsened by attempts at movement and stress. Commonly, patients may incorporate the involuntary movement into a more purposeful movement as an attempt to hide the chorea. The underlying causes of acute chorea are fairly limited (Table 1) (1). In the case presented, the chief differential diagnosis included acute rheumatic fever (ARF), systemic lupus erythematosus (SLE) and primary antiphospholipid antibody syndrome (aPLS). Differential diagnosis of chorea in children Table adapted from reference 1. CNS Central nervous system; MELAS Mitochondrial encephalopathy with lactic acidosis and stroke Differential diagnosis of chorea in children Table adapted from reference 1. CNS Central nervous system; MELAS Mitochondrial encephalopathy with lactic acidosis and stroke The patient was treated empirically with oral penicillin because of the possibility of ARF. On further questioning, there was no history of sore throat or skin infection; however, his mother had been diagnosed with impetigo several weeks earlier. A throat swab was negative for group A streptococcus, and antistreptolysin O titre was 200 U/L (normal <200 U/L). DNaseB testing was not available. An electrocardiogram revealed normal sinus rhythm with a PR interval of 154 ms (borderline for age). An echocardiogram showed mild mitral valve (MV) regurgitation. There were intracardiac vegetations, no pericardial effusion and cardiac function was normal. The patient did not have erythema marginatum, subcutaneous nodules or arthritis. Review of systems revealed no alopecia, photosensivity, rash, joint symptoms, chest pain or Raynaud's phenomenon. Further testing revealed a positive antinuclear antibody titre of 1:640 (by immunofluorescence), as well as positive anti-dsDNA and anticardiolipin (ACL) immunoglobulin G antibodies. He did not have proteinuria or hematuria. His erythrocyte sedimentation rate was 43 mm/h and C-reactive protein was 1.0 mg/L. Complement and immunoglobulin G levels were normal. International normalized ratio was normal, but initial prothrombin time (PTT) was elevated at 71 and did not correct with 50:50 mixing study, indicating the presence of an inhibitor or lupus anticoagulant. Management consisted of low-dose acetylsalicylic acid 81 mg daily and valproic acid 10 mg/kg/day. Over the following week, the chorea improved significantly and the patient was able to ambulate. Approximately two weeks after presentation, the patient developed a rash in the malar distribution (Figure 1). The patient's and family's consent were obtained to share the clinical information and photograph. A diagnosis of SLE was made on the basis of the malar rash, hematological abnormalities (leukopenia, lymphopenia, hemolytic anemia), positive antinuclear antibody, anti-dsDNA and ACL antibodies (Table 2) (2,3). The patient was started on hydroxychloroquine and his blood counts remained stable. In addition, the patient's chorea resolved completely and valproic acid was discontinued. Nine-and-a-half-year-old boy with chorea demonstrating a malar rash two weeks after presentation. 1997 ACR revised classification criteria for systemic lupus erythematosus* an abnormal serum level of IgG or IgM anticardiolipin antibodies; a positive test result for lupus anticoagulant using a standard method; or a false-positive test result for at least 6 months confirmed by Treponema pallidum immobilization or fluorescent treponemal antibody absorption test an abnormal serum level of IgG or IgM anticardiolipin antibodies; a positive test result for lupus anticoagulant using a standard method; or a false-positive test result for at least 6 months confirmed by Treponema pallidum immobilization or fluorescent treponemal antibody absorption test From References 2 and 3. ACR American College of Rheumatology; ECG Electrocardiogram; Ig Immunoglobulin 1997 ACR revised classification criteria for systemic lupus erythematosus* an abnormal serum level of IgG or IgM anticardiolipin antibodies; a positive test result for lupus anticoagulant using a standard method; or a false-positive test result for at least 6 months confirmed by Treponema pallidum immobilization or fluorescent treponemal antibody absorption test an abnormal serum level of IgG or IgM anticardiolipin antibodies; a positive test result for lupus anticoagulant using a standard method; or a false-positive test result for at least 6 months confirmed by Treponema pallidum immobilization or fluorescent treponemal antibody absorption test From References 2 and 3. ACR American College of Rheumatology; ECG Electrocardiogram; Ig Immunoglobulin Interestingly, valvular abnormalities including MV regurgitation and MV nodules occur with increased frequency in SLE. Valvular vegetations (Libman-Sacks endocarditis) may also occur. There is evidence that valvular disease may be more common in patients with SLE and antiphospholipid (aPL) antibodies, and they have also been seen in patients with primary aPLS (4,5). There is a possible pathogenic link between aPL antibodies, endothelial cell activation and development of valvular lesions (4). Chorea occurs in approximately 5% of paediatric patients with SLE. It is almost universally associated with the presence of aPL (lupus anticoagulant and ACL). With the decline in ARF in developed countries, the presence of chorea is more likely secondary to aPL rather than to ARF. Primary aPLS is quite uncommon in paediatric patients, and the syndrome occurs more commonly as part of underlying SLE. A clue to the presence of aPL antibodies is prolongation of PTT that does not correct with mixing study, indicating the presence of a ‘lupus inhibitor’. Despite a prolongation in PTT, the aPL antibodies lead to greater propensity for clotting and increased risk for arterial and venous thrombosis. Chorea is not considered to be one of the neurological criteria in the diagnosis of SLE (Table 2) and is treated differently than CNS lupus. Often, patients with SLE experience a single episode of chorea that subsides within days to a few months. The mainstay of treatment consists of symptomatic therapy with dopamine antagonists as well as antiplatelet therapy in patients with aPL (6). Immunosuppressive therapy (eg, glucocorticoids) can be considered in cases when generalized SLE disease activity is present. Chorea may be a presentation of SLE in children and occurs most often in the context of aPL antibodies. The main differential diagnosis includes ARF. The approach to treatment of chorea in SLE should include symptomatic therapy with dopamine antagonists, as well as anticoagulation therapy as appropriate for aPLS.

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