What does the DSI-IV define as: A. Both multiple motor and one or more vocal tics have been present at some time during the illness, although not necessarily concurrently. (A tic is a sudden, rapid, recurrent, nonrhythmic, stereotyped motor movement or vocalization.) B. The tics occur many times a day (usually in bouts) nearly every day or intermittently throughout a period of more than 1 year, and during this period there was never a tic-free period of more than 3 consecutive months. C. The onset is before age 18 years. D. The disturbance is not due to the direct physiological effects of a substance (e.g., stimulants) or a general medical condition (e.g., Huntington's disease or postviral encephalitis).
Tic disorder, and replaced the criterion that tics occur nearly every day with persistence for more than a year. The longer tic-free periods (months) allow that more have Tourette's Disorder or a Persistent (Chronic) tic disorder. Dystonias, paroxysmal dyskinesias, chorea, other genetic conditions, and secondary causes of tics should be ruled out in the differential diagnosis. Conditions besides Tourette syndrome that may manifest tics or stereotyped movements include developmental disorders, autism spectrum disorders, and stereotypic movement disorder; Sydenham's chorea; idiopathic dystonia; and genetic conditions such as Huntington's disease, neuroacanthocytosis, pantothenate kinase-associated neurodegeneration, Duchenne muscular dystrophy, Wilson's disease, and tuberous sclerosis. Other
Tic are not tics, because they do not involve a whole muscle. They are twitches of a few muscle fibre bundles, which can be felt but barely seen. Such eyelid twitches also differ from tics in that they are not suppressible, are strictly involuntary, and tend to fade after a day or two. 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