Tic Disorders: Phenomenology and Diagnostic Criteria

Childhood Disorders: Tic Disorders

Phenomenology and Diagnostic Criteria

The cardinal features of Tourette’s disorder and the other tic dis-orders are motor and vocal tics. Motor tics are usually brief, rapid and stereotyped movements, but can also be slower, more rhyth-mical, or even dystonic in nature. Simple motor tics are move-ments of individual muscle groups and include brief movements such as eye blinking, head shaking and shoulder shrugging. Com-plex motor tics involve multiple muscle groups, such as a simul-taneous eye deviation, head turn and shoulder shrug. Some com-plex tics appear more purposeful, such as stereotyped hopping, touching, rubbing, or obscene gestures (copropraxia). Vocal tics are usually brief, staccato-like sounds, but can also be words or phrases. Simple vocal tics, often caused by the forceful movement of air through the nose and mouth, include sniffing, throat clear-ing, grunting, or barking-type sounds. Complex vocal tics usu-ally include words, phrases, or the repetition of one’s own words (palilalia) or the words of others (echolalia). Coprolalia (repetition of obscene phrases), often incorrectly considered essential for the diagnosis of Tourette’s disorder, is an uncommon symptom with only 2 to 6% of Tourette’s disorder cases so affected.

Tics most often begin early in childhood, wax and wane in severity, and change in character and quality over time. Tics are exacerbated by excitement and tension, and can attenuate during periods of focused, productive activity and sleep. Tics are invol-untary, yet because they are briefly suppressible or can be trig-gered by environmental stimuli, they may appear as volitional acts. Patients describe tension developing if a tic is resisted, which only subsides by completion of the tic. In some individu-als, tics are preceded or provoked by a thought or physical sensa-tion referred to as a premonitory urge