Movement disorders in children and adolescents.

Tourette syndrome (TS), Sydenham chorea, and drug-induced dyskinesias are prototypical movement disorders affecting children. Underlying involvement of basal ganglia has been apparent for several decades, but new neuroimaging studies are adding detail to this mechanism. Genetic studies of TS and tardive dyskinesia may further reveal the underlying pathophysiology. Most provocative is the new conceptual model of poststreptococcal autoimmune neuropsychiatric disorder. Although unproven, substantial support for this model comes from immunologic, family, neuroimaging, and treatment studies.