Tic

A tic is a sudden, repetitive, nonrhythmic motor movement or vocalization involving discrete muscle groups. Tics can be invisible to the observer, such as abdominal tensing or toe crunching. Common motor and phonic tics are, respectively, eye blinking and throat clearing.

Tics must be distinguished from movements of other movement disorders such as chorea, dystonia, myoclonus; movements exhibited in stereotypic movement disorder or some autistic people, and the compulsions of obsessive-compulsive disorder (OCD) and seizure activity.

Classification

Tics are classified as either motor or phonic, and simple or complex.

Motor or phonic

Motor tics are movement-based tics affecting discrete muscle groups.

Phonic tics are involuntary sounds produced by moving air through the nose, mouth, or throat. They may be alternately referred to as verbal tics or vocal tics, but most diagnosticians prefer the term phonic tics to reflect the notion that the vocal cords are not involved in all tics that produce sound.