Sudden, repetitive, involuntary muscular movement or vocal
pattern. Tic disorders feature involuntary repetitive (but non-
rhythmic) patterns, and may be either motor tics (muscle
movements) or vocal tics. Although tics are involuntary, the
individual with a tic disorder can often repress the tic for a
period of time. The occurrences of tics appear to be more likely
when the individual is under stress or concentrating on a task,
such as reading or writing. Most tics seem to nearly disappear
during sleep. The Diagnostic and Statistical Manual of Mental
Disorders, 4th edition, lists the following examples: Both motor
and vocal tics may be categorized as simple or complex, although
the distinction between the two is not precise. Generally, a
simple motor tic involves only one part of the body, while a
complex tic is more involved and takes the form of some
recognizable action. They also include imitating the actions of
others and making involuntary obscene gestures. Complex vocal
tics involve recognizable words o