How are Tourette syndrome (TS) and other tic disorders differentiated from movement disorders?

Updated: May 30, 2019
  • Author: William C Robertson, Jr, MD; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP  more...
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Answer

Tics are distinguished from other movement disorders by several typical characteristics. First, tics are most commonly brief movements, yet not so brief as the movements of myoclonus.

Myoclonus is not suppressible, whereas tics (and chorea) are suppressible. Often, after prolonged forced suppression, a rebound of tic severity occurs, though this is hard to demonstrate in controlled settings. [143] Similarly, tics tend to improve somewhat when the individual is absorbed in an enjoyable or demanding activity.

Individual tics may resemble the individual movements of chorea, yet tics are repeated stereotyped movements, while chorea consists of movements that are unpredictably distributed through the body. For example, a man with tics may be "the guy who shakes his head," while someone with chorea may be simply "the guy that twitches a lot." However, in distinction to tremor or most stereotypies, including typical tardive dyskinesia, tics are not rhythmic.


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