In dsm-iv-tr, this category includes tourette’s disorder, chronic motor or vocal tic disorder, transient tic disorder, and tic disorder not otherwise specified; all but the last type begin before age 18 years. Chronic tics may occur many times a day, nearly every day, or intermittently over a period of more than a year. Transient tics do not persist for longer than 12 consecutive months.
Tics are sudden, repetitive, stereotyped motor movements or phonic productions that can be distinguished by their anatomical location, number, frequency, duration, and complexity. Tics are often described as being simple (i.e., involving one muscle group) or complex (i.e., involving multiple muscle groups in a sequential movement).