Tics are involuntary, rapid, repetitive, irregular movement (usually involving limited muscle groups) or vocal production that begins suddenly and clearly aimlessly.
Tics tend to feel overwhelming, but they can usually be suppressed for various periods of time.
Both motor and vocal tics can be classified as simple or complex, although the boundaries are poorly defined.
Common simple motor tics include blinking, neck twitching, shoulder shrugging, and grimacing.
Common simple and vocal tics include coughing, barking, snorting, sniffing, and hissing.
Common complex motor tics include self-tapping, bouncing, and jumping.
A common complex of vocal tics includes the repetition of specific words and sometimes the use of socially unacceptable (often obscene) words (coprolalia), and repetition of one’s own sounds or words (palilalia).
There is a huge variety in the severity of tics. On the one hand, the phenomenon is almost the norm, when one in five or ten children has transient tics at any time.
On the other hand, Gilles de la Tourette’s syndrome is a rare, chronic, disabling disorder. Tics are significantly more common in boys than in girls, and there is usually a hereditary burden.