Refers to sudden, repetitive, nonrhythmic motor movements or vocalizations involving discrete muscle groups.

Can be invisible to the observer.

Common motor and phonic tics are, respectively, eye blinking and throat clearing.

Described as semi-voluntary or unvoluntary.

They are not strictly involuntary, as they may be experienced as a voluntary response to the unwanted, premonitory urge.

Tic disorders are commonly considered to be childhood syndromes, but occasionally develop during adulthood

Adult-onset tics often have a secondary cause.

Must be distinguished from movement disorders such as chorea, dystonia, myoclonus; movements exhibited in stereotypic movement disorder or some autistic people, and the compulsions of obsessive–compulsive disorder and seizure activity.

Relative to other movement disorders, is that they are suppressible yet irresistible.

Tics are experienced as an irresistible urge that must eventually be expressed.

Classified as either motor or phonic, and simple or complex.

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.

The vocal cords are not involved in all tics that produce sound.

Simple motor tics are typically sudden, brief, meaningless movements that usually involve only one group of muscles, such as eye blinking, head jerking, or shoulder shrugging.

Motor tics may include such movements as hand clapping, neck stretching, mouth movements, head, arm or leg jerks, and facial grimacing.

A simple phonic tic can be almost any sound or noise.

Common vocal tics being throat clearing, sniffing, or grunting.

Complex motor tics may involve a cluster of movements and appear coordinated.

Complex motor tics appear more purposeful and are sustained.

Examples of complex motor tics are pulling at clothes, touching people, touching objects, echopraxia and copropraxia

Echopraxia is the repeating or imitating another person’s actions.

Coproptaxia is the involuntarily performing obscene or forbidden gestures.

Complex phonic tics include echolalia, palilalia, and coprolalia.

Echolalia is repeating words just spoken by someone else,

Palilalia is repeating one’s own previously spoken words.

Lexilalia os repeating words after reading them.

Coprolalia is the spontaneous utterance of socially objectionable or taboo words or phrases.

About 10% of TS patients exhibit coprolalia.

They may be increased as a result of stress, fatigue, boredom, or high-energy emotions, and anxiety.

They may be increased, as well, by positive emotions, such as excitement or anticipation.

Relaxation may result in a tic increase.

Concentration on an absorbing activity often leads to a decrease in tics.

Most individuals are aware of an urge that immediately precedes a tic.

Most are aware of an urge, that is similar to the need to yawn, sneeze, blink, or scratch an itch.

It is described as as a buildup of tension, that they consciously choose to release.

Individuals feel as if they have to do it, such as the urge to clear one’s throat, and may be felt as relieving this tension or sensation, similar to scratching an itch, or blinking to relieve an uncomfortable sensation in the eye.

Some may not be aware of the premonitory urge.

Children may be less aware of the premonitory urge than are adults, but their awareness tends to increase with maturity.

Tic disorders occur along a spectrum, ranging from mild to more severe.

Tourette syndrome is the more severe expression on the spectrum of tic disorders.

Tourette syndrome is thought to be due to the same genetic vulnerability.

Most cases of Tourette syndrome are not severe.

Many tics, such as throat clearing and eye blinking, are normal across populations.

Some tics represent disordered behavior from a psychiatric perspective.

The differential diagnosis includes: dystonias, paroxysmal dyskinesias, chorea, other genetic conditions, and secondary causes of tics.

Conditions that may manifest with tics include: Tourette syndrome, developmental disorders, autism spectrum disorders, and stereotypic movement disorder, Sydenham’s chorea, idiopathic dystonia; and genetic conditions such as Huntington’s disease, neuroacanthocytosis, Hallervorden-Spatz syndrome, Duchenne muscular dystrophy, Wilson’s disease, and tuberous sclerosis, chromosomal disorders such as Down syndrome, Klinefelter syndrome, XYY syndrome and fragile X syndrome.

Acquired causes of tics include drugs, head trauma, encephalitis, stroke, and carbon monoxide poisoning.

Onset that begin after the age of 18 are generally not considered symptoms of Tourette’s syndrome.

Tests to rule out other conditions include: EEG, MRI, TSH levels, urine drug screen for cocaine and stimulants, serum copper and ceruloplasmin levels.

Patients with obsessive-compulsive disorder (OCD) may present with features that may resemble motor tics.

They are to be distinguished from fasciculations.

Small twitches of the upper or lower eyelid, for example, are not tics.

Such small twitches do not involve a whole muscle, and involve a few muscle fibre bundles, felt but barely seen.

Eyelid twitches are not suppressible, are strictly involuntary, and tend to fade after a day or two.

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