Motor stereotypies.

Stereotypic movements are ubiquitous, occur in a variety of forms, and exist in different populations, ranging from individuals with autism to typically developing children. Although such movements are required to be restricted, repetitive, and purposeless, their definition and included activities remain broad and imprecise. Movements are typically classified into 2 groups, primary (physiological) and secondary (pathological), depending upon the presence of additional signs or symptoms. Although some view these movements as behaviors produced to alter a state of arousal, there is increasing evidence to support a neurobiological mechanism. Behavioral and pharmacological therapies have been used with varying effect.