A term used to describe a set of neurological
disorders that are characterized by one or more of several forms of tics. Tics
are defined as involuntary, sudden, rapid, recurrent, nonrythmic motor movements
(e.g., eye blinking, arm movements, head jerking, finger or hand movements,
facial twitches) or vocalizations (e.g., grunting, throat clearing). Compulsive
behavior and obsessive thinking may also be part of this disorder. Transient
tics are temporary, come and go, and may last only a few weeks or months.
Chronic tics are
unchanging and may persist for several years.