Tourette syndrome

Tourette syndrome, or simply Tourette's, is a motor disorder that begins in childhood or adolescence. It is characterized by multiple movement tics and at least one vocal tic. Common tics are blinking, coughing, throat clearing, sniffing, and facial movements. Tics are typically preceded by an unwanted urge or sensation in the affected area known as a premonitory urge, can sometimes be suppressed temporarily, and characteristically change in location, strength, and frequency. Tourette's is at the more severe end of the spectrum of tic disorders. The tics often go unnoticed by casual observers.
Tourette's was once regarded as a rare and bizarre syndrome and has popularly been associated with coprolalia. It is no longer considered rare; about 1% of school-age children and adolescents are estimated to have Tourette's, though coprolalia occurs only in a minority. There are no specific tests for diagnosing Tourette's; it is not always correctly identified, because most cases are mild, and the severity of tics decreases for most children as they pass through adolescence. Therefore, many go undiagnosed or may never seek medical attention. Extreme Tourette's in adulthood, often sensationalized in the media, is rare, but for a small minority, severely debilitating tics can persist into adulthood.
There is no cure for Tourette's and no single most effective medication. In most cases, medication for tics is not necessary, and behavioral therapies are the first-line treatment. Education is an important part of any treatment plan, and explanation alone often provides sufficient reassurance that no other treatment is necessary. Other conditions, such as attention deficit hyperactivity disorder and obsessive–compulsive disorder, are more likely to be present among those who are referred to specialty clinics than they are among the broader population of persons with Tourette's. These co-occurring conditions often cause more impairment to the individual than the tics; hence it is important to correctly distinguish co-occurring conditions and treat them.
Tourette syndrome was named by French neurologist Jean-Martin Charcot for his intern, Georges Gilles de la Tourette, who published in 1885 an account of nine patients with a "convulsive tic disorder". While the exact cause is unknown, it is believed to involve a combination of genetic and environmental factors. The mechanism appears to involve dysfunction in neural circuits between the basal ganglia and related structures in the brain.

Classification

Most published research on Tourette syndrome originates in the United States; in international TS research and clinical practice, the Diagnostic and Statistical Manual of Mental Disorders is preferred over the World Health Organization classification, which is criticized in the 2021 European Clinical Guidelines.
In the fifth revision of the DSM, published in 2013, Tourette syndrome is classified as a motor disorder. It is listed in the neurodevelopmental disorder category. Tourette's is at the more severe end of the spectrum of tic disorders; its diagnosis requires multiple motor tics and at least one vocal tic to be present for more than a year, and these first occurring before the age of 18. Tics are sudden, repetitive, nonrhythmic movements that involve discrete muscle groups, while vocal tics involve laryngeal, pharyngeal, oral, nasal or respiratory muscles to produce sounds. The tics must not be explained by other medical conditions or substance use.
Other tic disorders include persistent motor or vocal tics, in which one type of tic has been present for more than a year; and provisional tic disorder, in which motor or vocal tics have been present for less than one year. DSM-5 replaced what had been called transient tic disorder with provisional tic disorder, recognizing that "transient" can only be defined in retrospect. Some experts believe that TS and persistent motor or vocal tic disorder should be considered the same condition, because vocal tics are also motor tics in the sense that they are muscular contractions of nasal or respiratory muscles.
Tourette syndrome is defined only slightly differently by the WHO; in its ICD-11, the International Statistical Classification of Diseases and Related Health Problems, Tourette syndrome is classified as a disease of the nervous system and a neurodevelopmental disorder, and only one motor tic and one or more vocal tics are required for diagnosis. Older versions of the ICD called it "combined vocal and multiple motor tic disorder ".
Genetic studies indicate that tic disorders cover a spectrum that is not recognized by the clear-cut distinctions in the current diagnostic framework. Since 2008, studies have suggested that Tourette's is not a unitary condition with a distinct mechanism, as described in the existing classification systems. Instead, the studies suggest that subtypes should be recognized to distinguish "pure TS" from TS that is accompanied by attention deficit hyperactivity disorder, obsessive–compulsive disorder or other disorders, similar to the way that subtypes have been established for other conditions, such as type 1 and type 2 diabetes. Elucidation of these subtypes awaits fuller understanding of the genetic and other causes of tic disorders.

Characteristics

Tics

s are movements or sounds that take place "intermittently and unpredictably out of a background of normal motor activity", having the appearance of "normal behaviors gone wrong". The tics associated with Tourette's wax and wane; they change in number, frequency, severity, anatomical location, and complexity; each person experiences a unique pattern of fluctuation in their severity and frequency. Tics may also occur in "bouts of bouts", which also vary among people. The variation in tic severity may occur over hours, days, or weeks. Tics may increase when someone is experiencing stress, fatigue, anxiety, or illness, or when engaged in relaxing activities like watching TV. They sometimes decrease when an individual is engrossed in or focused on an activity like playing a musical instrument.
In contrast to the abnormal movements associated with other movement disorders, the tics of Tourette's are nonrhythmic, often preceded by an unwanted urge, and temporarily suppressible. Over time, about 90% of individuals with Tourette's feel an urge preceding the tic, similar to the urge to sneeze or scratch an itch. The urges and sensations that precede the expression of a tic are referred to as premonitory sensory phenomena or premonitory urges. People describe the urge to express the tic as a buildup of tension, pressure, or energy which they ultimately choose consciously to release, as if they "had to do it" to relieve the sensation or until it feels "just right". The urge may cause a distressing sensation in the part of the body associated with the resulting tic; the tic is a response that relieves the urge in the anatomical location of the tic. Examples of this urge are the feeling of having something in one's throat, leading to a tic to clear one's throat, or a localized discomfort in the shoulders leading to shrugging the shoulders. The actual tic may be felt as relieving this tension or sensation, similar to scratching an itch or blinking to relieve an uncomfortable feeling in the eye. Some people with Tourette's may not be aware of the premonitory urge associated with tics. Children may be less aware of it than are adults, but their awareness tends to increase with maturity; by the age of ten, most children recognize the premonitory urge.
Premonitory urges which precede the tic make suppression of the impending tic possible. Because of the urges that precede them, tics are described as semi-voluntary or unvoluntary, rather than specifically involuntary; they may be experienced as a voluntary, suppressible response to the unwanted premonitory urge. The ability to suppress tics varies among individuals, and may be more developed in adults than children. People with tics are sometimes able to suppress them for limited periods of time, but doing so often results in tension or mental exhaustion. People with Tourette's may seek a secluded spot to release the suppressed urge, or there may be a marked increase in tics after a period of suppression at school or work. Children may suppress tics while in the doctor's office, so they may need to be observed when not aware of being watched.
Complex tics related to speech include coprolalia, echolalia and palilalia. Coprolalia is the spontaneous utterance of socially objectionable or taboo words or phrases. Although it is the most publicized symptom of Tourette's, only about 10% of people with Tourette's exhibit it, and it is not required for a diagnosis. Echolalia and palilalia occur in a minority of cases. Complex motor tics include copropraxia, echopraxia and palipraxia.

Onset and progression

There is no typical case of Tourette syndrome, but the age of onset and the severity of symptoms follow a fairly reliable course. Although onset may occur anytime before eighteen years, the typical age of onset of tics is from five to seven, and is usually before adolescence. A 1998 study from the Yale Child Study Center showed that tic severity increased with age until it reached its highest point between ages eight and twelve. Severity declines steadily for most children as they pass through adolescence, when half to two-thirds of children see a dramatic decrease in tics.
In people with TS, the first tics to appear usually affect the head, face, and shoulders, and include blinking, facial movements, sniffing and throat clearing. Vocal tics often appear months or years after motor tics but can appear first. Among people who experience more severe tics, complex tics may develop, including "arm straightening, touching, tapping, jumping, hopping and twirling". There are different movements in contrasting disorders, such as self-stimulation and stereotypies.
The severity of symptoms varies widely among people with Tourette's, and many cases may be undetected. Most cases are mild and almost unnoticeable; many people with TS may not realize they have tics. Because tics are more commonly expressed in private, Tourette syndrome may go unrecognized, and casual observers might not notice tics. Most studies of TS involve males, who have a higher prevalence of TS than females, and gender-based differences are not well studied; a 2021 review suggested that the characteristics and progression for females, particularly in adulthood, may differ and better studies are needed.
Most adults with TS have mild symptoms and do not seek medical attention. While tics subside for the majority after adolescence, some of the "most severe and debilitating forms of tic disorder are encountered" in adults. In some cases, what appear to be adult-onset tics can be childhood tics re-surfacing.