Tourette's is one of several tic disorders, which are classified by the ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM) according to type (motor or phonic tics) and duration (transient or chronic). Transient tic disorder consists of multiple motor tics, phonic tics or both, with a duration between four weeks and twelve months. Chronic tic disorder is either single or multiple, motor or phonic tics (but not both), which are present for more than a year. Tic disorders are defined similarly by the World Health Organization (International Statistical Classification of Diseases and Related Health Problems, ICD-10 codes).
Tics are sudden, repetitive, stereotyped, nonrhythmic movements (motor tics) and utterances (phonic tics) that involve discrete muscle groups. Motor tics are movement-based tics, while phonic tics are involuntary sounds produced by moving air through the nose, mouth, or throat.
Although Tourette's is the more severe expression of the spectrum of tic disorders, most cases are mild. The severity of symptoms varies widely among people with Tourette's, and mild cases may be undetected. having the appearance of "normal behaviors gone wrong". The tics associated with Tourette's constantly change in number, frequency, severity and anatomical location. Waxing and waning—the ongoing increase and decrease in severity and frequency of tics—occurs differently in each individual. Tics also occur in "bouts of bouts", which vary for each person. Echolalia (repeating the words of others) and palilalia (repeating one's own words) occur in a minority of cases,
In contrast to the abnormal movements of other movement disorders (for example, choreas, dystonias, myoclonus, and dyskinesias), the tics of Tourette's are stereotypic, temporarily suppressible, nonrhythmic, and often preceded by an unwanted premonitory urge. Immediately preceding tic onset, most individuals with Tourette's are aware of an urge, similar to the need to sneeze or scratch an itch. Individuals describe the need to tic as a buildup of tension, pressure, or energy which they consciously choose to release, as if they "had to do it" to relieve the sensation
While individuals with tics are sometimes able to suppress their tics for limited periods of time, doing so often results in an explosion of tics afterward. The ability to suppress tics varies among individuals, and may be more developed in adults than children.
Although there is no such thing as a "typical" case of Tourette syndrome, showed that the ages of highest tic severity are eight to twelve (average ten), with tics steadily declining for most patients as they pass through adolescence. Tics that appear early in the course of the condition are frequently confused with other conditions, such as allergies, asthma, and vision problems: pediatricians, allergists and ophthalmologists are typically the first to see a child with tics. One author reports that a ten-year overview of patient records revealed about 40% of patients with Tourette's have "TS-only" or "pure TS", referring to Tourette syndrome in the absence of ADHD, OCD and other disorders. Another author reports that 57% of 656 patients presenting with tic disorders had uncomplicated tics, while 43% had tics plus comorbid conditions. Genetic studies have shown that the overwhelming majority of cases of Tourette's are inherited, although the exact mode of inheritance is not yet known, and no gene has been identified. In other cases, tics are associated with disorders other than Tourette's, a phenomenon known as ''tourettism''.
A person with Tourette's has about a 50% chance of passing the gene(s) to one of his or her children, but Tourette's is a condition of variable expression and incomplete penetrance. Thus, not everyone who inherits the genetic vulnerability will show symptoms; even close family members may show different severities of symptoms, or no symptoms at all. The gene(s) may express as Tourette's, as a milder tic disorder (transient or chronic tics), or as obsessive–compulsive symptoms without tics. Only a minority of the children who inherit the gene(s) have symptoms severe enough to require medical attention. Gender appears to have a role in the expression of the genetic vulnerability: males are more likely than females to express tics. Children who meet five diagnostic criteria are classified, according to the hypothesis, as having Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS). This contentious hypothesis is the focus of clinical and laboratory research, but remains unproven.
The exact mechanism affecting the inherited vulnerability to Tourette's has not been established, and the precise etiology is unknown. Tics are believed to result from dysfunction in cortical and subcortical regions, the thalamus, basal ganglia and frontal cortex.
Some forms of OCD may be genetically linked to Tourette's. A subset of OCD is thought to be etiologically related to Tourette's and may be a different expression of the same factors that are important for the expression of tics. The genetic relationship of ADHD to Tourette syndrome, however, has not been fully established. The onset must have occurred before the age of 18, and cannot be attributed to the "direct physiological effects of a substance or a general medical condition". it is frequently misdiagnosed or underdiagnosed, partly because of the wide expression of severity, ranging from mild (the majority of cases) or moderate, to severe (the rare, but more widely-recognized and publicized cases). TSH levels can be measured to rule out hypothyroidism, which can be a cause of tics. Brain imaging studies are not usually warranted. 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. Disruptive behaviors, impaired functioning, or cognitive impairment in patients with comorbid Tourette's and ADHD may be accounted for by the comorbid ADHD, highlighting the importance of identifying and treating comorbid conditions. Disruption from tics is commonly overshadowed by comorbid conditions that present greater interference to the child. Treatments, where warranted, can be divided into those that target tics and comorbid conditions, which, when present, are often a larger source of impairment than the tics themselves.
Medication is available to help when symptoms interfere with functioning. Risperdal), ziprasidone (Geodon), haloperidol (Haldol), pimozide (Orap) and fluphenazine (Prolixin)—can have long-term and short-term adverse effects. and there is increasing evidence supporting the use of habit reversal in the treatment of tics. Relaxation techniques, such as exercise, yoga or meditation, may be useful in relieving the stress that may aggravate tics, but the majority of behavioral interventions (such as relaxation training and biofeedback, with the exception of habit reversal) have not been systematically evaluated and are not empirically supported therapies for Tourette's.
Further Reading
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