Motor disorders may involve developmental delays and deficits involving fine and gross motor functions. Developmental coordination disorder is characterized by deficits in the acquisition and execution of coordinated motor skills and is manifested by clumsiness and slowness or inaccuracy of performance of motor skills that cause interference with daily living. Stereotypic movement disorder includes patterns of repetitive and seemingly driven yet purposeless motor behaviors. Examples of such behaviors include movements of the head, body, and hands that are developmentally abnormal. Tic disorders involve sudden, rapid and recurrent, non-rhythmic motor movements or vocalizations. Such motoric or vocal manifestations are observably involuntary.
Several types of tic disorders can be distinguished in DSM-5. These are as follows:
- Tourette’s disorder
- Persistent (chronic) motor tic disorder
- Persistent (chronic) vocal tic disorder
Tourette’s disorder is characterized by the presence of multiple motor tics and one or more vocal tics. Persistent (chronic) motor tic disorder is characterized by the presence of single or multiple motor tics and the absence of any vocal tics. Persistent (chronic) vocal tic disorder is characterized by the presence of a single or multiple vocal tics and the absence of any motor tics.
Tics can be simple (of short duration) and can include motor behaviors such as eye blinking, shoulder shrugging, or movement of the extremities, or vocal behaviors such as throat clearing, sniffing, and grunting. Complex tics are of longer duration (on the order of seconds) and may include combinations of motor or vocal behaviors. Complex tics may involve imitating another person’s motor or vocal behaviors, sexual or obscene gestures (copropraxia) or utterances (coprolalia), or they may be apparently nonsensical combinations of motions and/or vocalizations.
Because many individuals experience one or more tics at some point in their lives, a tic disorder is diagnosed only when the tics persist for one year or longer.