Definition

A tic is a nonvoluntary body movement or vocal sound that is made repeatedly, rapidly, and suddenly. It has a stereotyped but nonrhythmic character. The child or adolescent with a tic experiences it as irresistible but can suppress the movement or noise for a period of time. Tics are categorized as motor or vocal, and as simple or complex. The word "tic" itself is French.

Tics are a type of dyskinesia, which is the general medical term given to impairments or distortions of voluntary movements. Although tics vary considerably in severity, they are associated with several neuropsychiatric disorders in children and adolescents. The American Psychiatric Association (APA) defined four tic disorders in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders, or DSM-IV. The disorders are distinguished from one another...