Sydenham's chorea, and its complications affecting the nervous system.

The well-known symptoms of rheumatic fever and Sydenham's chorea are briefly discussed. Then the associated psychiatric and neurological disorders are considered, especially the obsessive-compulsive and the attention deficit hyperactivity disorders; all linked to previous haemolytic streptococcal infections. Dystonic syndromes, and acute disseminated encephalopathies, also show such links; and may be part of the clinical spectrum of the post-infectious streptococcal illnesses. The causes of Sydenham's chorea are considered, especially an immune reactivity against the basal ganglia, supported by the finding of antibodies reactive against the neurons of the caudate nucleus. The resulting imbalance between dopaminergic and cholinergic systems may cause the involuntary choreiform movements, and account for the beneficial effects of certain drugs. The differential diagnosis of Sydenham's chorea is discussed, and the role of tests such as special imaging techniques. The possible treatments include prophylaxis with penicillin and the use of drugs like sodium valproate, carbamazapine and haloperidol. Immune therapy occupies a special role in selected patients, There is still a need for research into the links between these conditions.