Tic
Encyclopedia
A tic is a sudden, repetitive, nonrhythmic, stereotyped 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. Movements of other movement disorder
s (for example, chorea
, dystonia
, myoclonus
) must be distinguished from tics. Other conditions, such as autism
and stereotypic movement disorder
, also include movements that may be confused with tics. Tics must also be distinguished from the compulsions of OCD
and from seizure
activity.
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.
Tics may increase as a result of stress
, fatigue, boredom, or high-energy emotions, which can include negative emotions, such as anxiety
, but positive emotions as well, such as excitement or anticipation. Relaxation may result in a tic increase (for instance, watching television or using a computer), while concentration on an absorbing activity often leads to a decrease in tics. Neurologist and writer Oliver Sacks
described a physician with severe Tourette syndrome
(Canadian Mort Doran, M.D., a pilot and surgeon in real life, although a pseudonym
was used in the book), whose tics remitted almost completely while he was performing surgery.
Immediately preceding tic onset, most individuals are aware of an urge that is similar to the need to yawn, sneeze, blink, or scratch an itch. Individuals describe the need to tic as a buildup of tension that they consciously choose to release, as if they "had to do it". Examples of this premonitory urge are the feeling of having something in one's throat or a localized discomfort in the shoulders, leading to the need to clear one's throat or shrug the shoulders. The actual tic may be felt as relieving this tension or sensation, similar to scratching an itch. Another example is blinking to relieve an uncomfortable sensation in the eye.
Tics are described as semi-voluntary or unvoluntary, because they are not strictly involuntary—they may be experienced as a voluntary response to the unwanted, premonitory urge. A unique aspect of tics, relative to other movement disorders, is that they are suppressible yet irresistible; they are experienced as an irresistible urge that must eventually be expressed. Some people with tics may not be aware of the premonitory urge. Children may be less aware of the premonitory urge associated with tics than are adults, but their awareness tends to increase with maturity.
A simple phonic tic can be almost any sound or noise, with common vocal tics being throat clearing, sniffing, or grunting.
and copropraxia
.
Complex phonic tics may fall into various series (categories), including echolalia
(repeating words just spoken by someone else), palilalia
(repeating one's own previously spoken words), lexilalia (repeating words after reading them), and coprolalia
(the spontaneous utterance of socially objectionable or taboo words or phrases). Coprolalia is a highly publicized symptom of Tourette syndrome
; however, only about 10% of TS patients exhibit coprolalia.
Complex tics are rarely seen in the absence of simple tics. Tics "may be challenging to differentiate from compulsions", as in the case of klazomania
(compulsive shouting).
.
s, 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 disorder
s, 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
. Other possibilities include chromosomal disorders such as Down syndrome
, Klinefelter's syndrome
, XYY syndrome
and fragile X syndrome
. Acquired causes of tics include drug-induced tics, head trauma, encephalitis
, stroke
, and carbon monoxide poisoning
. Most of these conditions are rarer than tic disorders, and a thorough history and examination may be enough to rule them out, without medical or screening tests.
Although tic disorders are commonly considered to be childhood syndromes, tics occasionally develop during adulthood; adult-onset tics often have a secondary cause. Tics that begin after the age of 18 are generally not considered symptoms of Tourette's syndrome.
Tests may be ordered as necessary to rule out other conditions: For example, when diagnostic confusion between tics and seizure
activity exists, an EEG
may be ordered, or symptoms may indicate that an MRI is needed to rule out brain abnormalities. TSH
levels can be measured to rule out hypothyroidism
, which can be a cause of tics. Brain imaging studies are not usually warranted. In teenagers and adults presenting with a sudden onset of tics and other behavioral symptoms, a urine drug screen for cocaine
and stimulants might be necessary. If a family history of liver disease
is present, serum copper and ceruloplasmin
levels can rule out Wilson's disease
. most cases are mild.
Tics must be distinguished from fasciculation
s. Small twitches of the upper or lower eyelid, for example, are not tics, because they do not involve a whole muscle. They are twitches of a few muscle fibre bundles, which one can feel but barely see.
The Tourette Syndrome Classification Study Group. "Definitions and classification of tic disorders". Arch. Neurol. 50 (10): 1013-6. PMID 8215958. Retrieved on 2005-03-22
Movement disorder
Movement disorders include:* Akathisia * Akinesia * Associated Movements * Athetosis...
s (for example, chorea
Chorea (disease)
Choreia is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term choreia is derived from the Greek word χορεία , see choreia , as the quick movements of the feet or hands are vaguely comparable to dancing or piano playing.The term...
, dystonia
Dystonia
Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...
, myoclonus
Myoclonus
Myoclonus is brief, involuntary twitching of a muscle or a group of muscles. It describes a medical sign and, generally, is not a diagnosis of a disease. Brief twitches are perfectly normal. The myoclonic twitches are usually caused by sudden muscle contractions; they also can result from brief...
) must be distinguished from tics. Other conditions, such as autism
Autism
Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...
and stereotypic movement disorder
Stereotypic movement disorder
Stereotypic movement disorder is a disorder of childhood involving repetitive, nonfunctional motor behavior , that markedly interferes with normal activities or results in bodily injury, and persists for four weeks or longer. The behavior must not be due to the direct effects of a substance or...
, also include movements that may be confused with tics. Tics must also be distinguished from the compulsions of OCD
Obsessive-compulsive disorder
Obsessive–compulsive disorder is an anxiety disorder characterized by intrusive thoughts that produce uneasiness, apprehension, fear, or worry, by repetitive behaviors aimed at reducing the associated anxiety, or by a combination of such obsessions and compulsions...
and from seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
activity.
Description and classification
Tics are classified as motor vs. phonic and simple vs. 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. 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.
Tics may increase as a result of stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
, fatigue, boredom, or high-energy emotions, which can include negative emotions, such as anxiety
Anxiety
Anxiety is a psychological and physiological state characterized by somatic, emotional, cognitive, and behavioral components. The root meaning of the word anxiety is 'to vex or trouble'; in either presence or absence of psychological stress, anxiety can create feelings of fear, worry, uneasiness,...
, but positive emotions as well, such as excitement or anticipation. Relaxation may result in a tic increase (for instance, watching television or using a computer), while concentration on an absorbing activity often leads to a decrease in tics. Neurologist and writer Oliver Sacks
Oliver Sacks
Oliver Wolf Sacks, CBE , is a British neurologist and psychologist residing in New York City. He is a professor of neurology and psychiatry at Columbia University, where he also holds the position of Columbia Artist...
described a physician with severe Tourette syndrome
Tourette syndrome
Tourette syndrome is an inherited neuropsychiatric disorder with onset in childhood, characterized by multiple physical tics and at least one vocal tic; these tics characteristically wax and wane...
(Canadian Mort Doran, M.D., a pilot and surgeon in real life, although a pseudonym
Pseudonym
A pseudonym is a name that a person assumes for a particular purpose and that differs from his or her original orthonym...
was used in the book), whose tics remitted almost completely while he was performing surgery.
Immediately preceding tic onset, most individuals are aware of an urge that is similar to the need to yawn, sneeze, blink, or scratch an itch. Individuals describe the need to tic as a buildup of tension that they consciously choose to release, as if they "had to do it". Examples of this premonitory urge are the feeling of having something in one's throat or a localized discomfort in the shoulders, leading to the need to clear one's throat or shrug the shoulders. The actual tic may be felt as relieving this tension or sensation, similar to scratching an itch. Another example is blinking to relieve an uncomfortable sensation in the eye.
Tics are described as semi-voluntary or unvoluntary, because they are not strictly involuntary—they may be experienced as a voluntary response to the unwanted, premonitory urge. A unique aspect of tics, relative to other movement disorders, is that they are suppressible yet irresistible; they are experienced as an irresistible urge that must eventually be expressed. Some people with tics may not be aware of the premonitory urge. Children may be less aware of the premonitory urge associated with tics than are adults, but their awareness tends to increase with maturity.
Simple tics
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 can be of an endless variety and 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, with common vocal tics being throat clearing, sniffing, or grunting.
Complex tics
Complex motor tics are typically more purposeful-appearing and of a longer nature. They may involve a cluster of movements and appear coordinated. Examples of complex motor tics are pulling at clothes, touching people, touching objects, echopraxiaEchopraxia
Echopraxia is the involuntary repetition or imitation of the observed movements of another. It is closely related to echolalia, the involuntary repetition of another's speech. The etymology of the term is from Ancient Greek: "ἠχώ from ἠχή " and "πρᾶξις "...
and copropraxia
Copropraxia
Copropraxia is a tic consisting of involuntarily performing obscene or forbidden gestures, or inappropriate touching. Copropraxia comes from the Greek κόπρος meaning "feces" and πράξις meaning "action"...
.
Complex phonic tics may fall into various series (categories), including echolalia
Echolalia
Echolalia is the automatic repetition of vocalizations made by another person. It is closely related to echopraxia, the automatic repetition of movements made by another person....
(repeating words just spoken by someone else), palilalia
Palilalia
Palilalia is the repetition or echoing of one's own spoken words. It can be a complex tic, like echolalia and coprolalia and may sound like stuttering; all can be symptoms of Tourette syndrome, obsessive–compulsive disorder, or autism...
(repeating one's own previously spoken words), lexilalia (repeating words after reading them), and coprolalia
Coprolalia
Coprolalia is involuntary swearing or the involuntary utterance of obscene words or socially inappropriate and derogatory remarks. Coprolalia comes from the Greek κόπρος meaning "feces" and λαλιά from lalein, "to talk"...
(the spontaneous utterance of socially objectionable or taboo words or phrases). Coprolalia is a highly publicized symptom of Tourette syndrome
Tourette syndrome
Tourette syndrome is an inherited neuropsychiatric disorder with onset in childhood, characterized by multiple physical tics and at least one vocal tic; these tics characteristically wax and wane...
; however, only about 10% of TS patients exhibit coprolalia.
Complex tics are rarely seen in the absence of simple tics. Tics "may be challenging to differentiate from compulsions", as in the case of klazomania
Klazomania
Klazomania refers to compulsive shouting; it has features resembling the complex tics such as echolalia, palilalia and coprolalia seen in tic disorders, but has been seen in people with encephalitis lethargica, alcohol abuse and carbon monoxide poisoning. It was first reported by L. Benedek in...
(compulsive shouting).
Tic disorders
Tic disorders occur along a spectrum, ranging from mild to more severe, and are classified according to duration and severity (transient tics, chronic tics, or Tourette syndrome). Tourette syndrome is the more severe expression of a spectrum of tic disorders, which are thought to be due to the same genetic vulnerability. Nevertheless, most cases of Tourette syndrome are not severe. The treatment for the spectrum of tic disorders is similar to the treatment of Tourette syndromeTreatment of Tourette syndrome
Tourette syndrome is an inherited neuropsychiatric disorder with onset in childhood, characterized by the presence of motor and phonic tics...
.
Differential diagnosis
DystoniaDystonia
Dystonia is a neurological movement disorder, in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures. The disorder may be hereditary or caused by other factors such as birth-related or other physical trauma, infection, poisoning or reaction to...
s, paroxysmal dyskinesias, chorea, other genetic conditions, and secondary causes of tics should be ruled out in the differential diagnosis
Differential diagnosis
A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...
. Conditions besides Tourette syndrome that may manifest tics or stereotyped movements include developmental disorder
Developmental disorder
Developmental disorders occur at some stage in a child's development, often retarding the development. These may include,psychological or physical disorders. The disorder is an impairment in the normal development of motor or cognitive skills that are developed before age 18 in which they are...
s, autism spectrum disorders, and stereotypic movement disorder
Stereotypic movement disorder
Stereotypic movement disorder is a disorder of childhood involving repetitive, nonfunctional motor behavior , that markedly interferes with normal activities or results in bodily injury, and persists for four weeks or longer. The behavior must not be due to the direct effects of a substance or...
; Sydenham's chorea
Sydenham's chorea
Sydenham's chorea or chorea minor is a disease characterized by rapid, uncoordinated jerking movements affecting primarily the face, feet and hands. Sydenham's chorea results from childhood infection with Group A beta-hemolytic Streptococci and is reported to occur in 20-30% of patients with...
; idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
dystonia; and genetic conditions such as Huntington's disease
Huntington's disease
Huntington's disease, chorea, or disorder , is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and dementia. It typically becomes noticeable in middle age. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea...
, neuroacanthocytosis
Neuroacanthocytosis
Neuroacanthocytosis is a term that refers to a group of genetically diverse conditions complicated by movement disorders, neurological problems and spiculated red blood cells...
, Hallervorden-Spatz syndrome, Duchenne muscular dystrophy
Duchenne muscular dystrophy
Duchenne muscular dystrophy is a recessive X-linked form of muscular dystrophy, which results in muscle degeneration, difficulty walking, breathing, and death. The incidence is 1 in 3,000 boys. Females and males are affected, though females are rarely affected and are more often carriers...
, Wilson's disease, and tuberous sclerosis
Tuberous sclerosis
Tuberous sclerosis or tuberous sclerosis complex is a rare multi-system genetic disease that causes non-malignant tumors to grow in the brain and on other vital organs such as the kidneys, heart, eyes, lungs, and skin. A combination of symptoms may include seizures, developmental delay, behavioral...
. Other possibilities include chromosomal disorders such as Down syndrome
Down syndrome
Down syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th...
, Klinefelter's syndrome
Klinefelter's syndrome
Klinefelter syndrome, 46/47, XXY, or XXY syndrome is a condition in which human males have an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome...
, XYY syndrome
XYY syndrome
XYY syndrome is an aneuploidy of the sex chromosomes in which a human male receives an extra Y-chromosome, giving a total of 47 chromosomes instead of the more usual 46. This produces a 47,XYY karyotype...
and fragile X syndrome
Fragile X syndrome
Fragile X syndrome , Martin–Bell syndrome, or Escalante's syndrome , is a genetic syndrome that is the most commonly known single-gene cause of autism and the most common inherited cause of intellectual disability...
. Acquired causes of tics include drug-induced tics, head trauma, encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
, stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
, and carbon monoxide poisoning
Carbon monoxide poisoning
Carbon monoxide poisoning occurs after enough inhalation of carbon monoxide . Carbon monoxide is a toxic gas, but, being colorless, odorless, tasteless, and initially non-irritating, it is very difficult for people to detect...
. Most of these conditions are rarer than tic disorders, and a thorough history and examination may be enough to rule them out, without medical or screening tests.
Although tic disorders are commonly considered to be childhood syndromes, tics occasionally develop during adulthood; adult-onset tics often have a secondary cause. Tics that begin after the age of 18 are generally not considered symptoms of Tourette's syndrome.
Tests may be ordered as necessary to rule out other conditions: For example, when diagnostic confusion between tics and seizure
Seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
activity exists, an EEG
Electroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
may be ordered, or symptoms may indicate that an MRI is needed to rule out brain abnormalities. TSH
Thyroid-stimulating hormone
Thyrotrophin-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland, which regulates the endocrine function of the thyroid gland.- Physiology :...
levels can be measured to rule out hypothyroidism
Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone.Iodine deficiency is the most common cause of hypothyroidism worldwide but it can be caused by other causes such as several conditions of the thyroid gland or, less commonly, the pituitary gland or...
, which can be a cause of tics. Brain imaging studies are not usually warranted. In teenagers and adults presenting with a sudden onset of tics and other behavioral symptoms, a urine drug screen for cocaine
Cocaine
Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. The name comes from "coca" in addition to the alkaloid suffix -ine, forming cocaine. It is a stimulant of the central nervous system, an appetite suppressant, and a topical anesthetic...
and stimulants might be necessary. If a family history of liver disease
Liver disease
Liver disease is a broad term describing any single number of diseases affecting the liver.-Diseases:* Hepatitis, inflammation of the liver, caused mainly by various viruses but also by some poisons , autoimmunity or hereditary conditions...
is present, serum copper and ceruloplasmin
Ceruloplasmin
Ceruloplasmin is a ferroxidase enzyme that in humans is encoded by the CP gene.Ceruloplasmin is the major copper-carrying protein in the blood, and in addition plays a role in iron metabolism. It was first described in 1948...
levels can rule out Wilson's disease
Wilson's disease
Wilson's disease or hepatolenticular degeneration is an autosomal recessive genetic disorder in which copper accumulates in tissues; this manifests as neurological or psychiatric symptoms and liver disease...
. most cases are mild.
Tics must be distinguished from fasciculation
Fasciculation
A fasciculation , or "muscle twitch", is a small, local, involuntary muscle contraction and relaxation visible under the skin arising from the spontaneous discharge of a bundle of skeletal muscle fibers...
s. Small twitches of the upper or lower eyelid, for example, are not tics, because they do not involve a whole muscle. They are twitches of a few muscle fibre bundles, which one can feel but barely see.
Further reading
- Black, Kevin J. Tourette Syndrome and Other Tic Disorders.
- Evidente, GH. "Is it a tic or Tourette's? Clues for differentiating simple from more complex tic disorders." PostGraduate Medicine Online. October 2000 108:5.
- Swerdlow, NR. "Tourette Syndrome: Current Controversies and the Battlefield Landscape". Curr Neurol Neurosci Rep. 2005, 5:329-331. PMID 16131414
The Tourette Syndrome Classification Study Group. "Definitions and classification of tic disorders". Arch. Neurol. 50 (10): 1013-6. PMID 8215958. Retrieved on 2005-03-22