Movement disorders, dystonia and chorea: SAQ

This girl presents the classic picture of Sydenham chorea, the neurologic manifestation of acute rheumatic fever, which follows group A streptococcal infection by weeks to months and is a major Jones criterion. The asymmetric flowing movements, the emotional lability and obsessional behaviour, the hypotonia, the motor impersistence with a milkmaid grip and darting tongue, and the preceding sore throat fit the diagnosis, and the echocardiographic mitral regurgitation confirms rheumatic carditis. [4]

Question 1 (10 marks)

Define the movement disorder this girl shows, outline your diagnostic workup, and describe your immediate and long-term management. [4]

This girl has chorea, defined as flowing, unpredictable, semi-purposeful movements that the child cannot suppress, with motor impersistence shown by the milkmaid grip and the darting tongue. The diagnosis is Sydenham chorea, which is a major criterion of acute rheumatic fever following group A streptococcal infection. [4]

My diagnostic workup confirms recent streptococcal infection and assesses the heart. I send anti-streptolysin O and anti-DNase B titres and a throat swab, request an echocardiogram and electrocardiogram because rheumatic carditis may be clinically silent, and arrange a basic infection and autoimmune screen. An EEG is sent only if there is doubt about whether the movements represent a seizure. The diagnosis is clinical, based on the Jones criteria, and the antibody results support rather than establish it. [4]

My immediate management is supportive, with a calm environment, rest, and attention to hydration, safety, and the emotional distress that accompanies the illness. For moderate or severe chorea I add a symptomatic drug such as valproate, carbamazepine, or a neuroleptic, titrated to control the movements. For severe or refractory chorea, the evidence supports a short course of corticosteroids. I do not use metoclopramide, because dopamine-blocking antiemetics can worsen movement disorders and precipitate an acute dystonic reaction. [5]

My long-term management is secondary penicillin prophylaxis to prevent recurrence of acute rheumatic fever and to protect the heart. I start intramuscular benzathine penicillin G every four weeks, at a dose of 600,000 units for a child weighing 27 kilograms or less and 1,200,000 units for a heavier child. This girl weighs 32 kilograms, so she receives 1,200,000 units every four weeks, continued into early adulthood per the local rheumatic fever guideline. I arrange paediatric cardiology follow-up for surveillance of the rheumatic heart disease, and I address the cultural and remote-access needs of her family with an Aboriginal health worker and a clear retrieval and follow-up pathway. [4]