Autoimmunity and the basal ganglia: new insights into old diseases.

Sydenham's chorea (SC) occurs weeks or months after Group A streptococcal infection, and is characterized by involuntary, purposeless movements of the limbs, in addition to behavioural alteration. There is a body of evidence which suggests that SC is an immune-mediated brain disorder with regional localization to the basal ganglia. Recent reports have suggested that the spectrum of post-streptococcal CNS disease is broader than chorea alone, and includes other hyperkinetic movement disorders (tics, dystonia and myoclonus). In addition, there are high rates of behavioural sequelae, particularly emotional disorders such as obsessive-compulsive disorder, anxiety and depression. These findings have lead to the hypothesis that similar immune-mediated basal ganglia processes may be operating in common neuropsychiatric disease such as tic disorders, Tourette syndrome and obsessive-compulsive disorder. This review analyses the historical aspects of post-streptococcal CNS disease, and the recent immunological studies which have addressed the hypothesis that common neuropsychiatric disorders may be secondary to basal ganglia autoimmunity.