A tic is a sudden, repetitive, stereotyped, nonrhythmic movement (motor tic) or sound (phonic tic) that involves discrete groups of muscles. Tics can be invisible to the observer (for example; abdominal tensing or toe crunching). Movements of other movement disorders (for example; chorea, dystonia, myoclonus) must be distinguished from tics. Other conditions (for example; autism, stereotypic movement disorder) also include movements which may be confused with tics. Tics must also be distinguish… (More on Tic)