Tourette syndrome (TS) is an inherited disorder of the nervous system, characterized by a variable expression of unwanted movements and noises ( tics ).
Tourette syndrome is also known as Gilles de la Tourette syndrome, named after Gilles de la Tourette, a French neurologist who first described the syndrome in 1885. Children with Tourette syndrome show symptoms before the age of 18, usually around age seven, and have symptoms that usually last into adulthood. The symptoms of Tourette syndrome are usually motor and/or vocal tics, although in some children other symptoms such as socially inappropriate comments, and socially inappropriate or self-injurious behaviors sometimes occur. Children with Tourette syndrome are more likely to have obsessive-compulsive disorder (OCD), attention deficient disorder (ADD), and attention deficit hyperactivity disorder (ADHD). The symptoms of Tourette syndrome are extremely variable over time, with some symptoms beginning and some ceasing to be a problem as the child grows. Many people with Tourette syndrome experience a decrease in symptoms as they age, and some people see a complete disappearance of their symptoms.
Tourette syndrome is found in all populations and all ethnic groups, but is three to four times more common in males than females. The exact frequency of Tourette syndrome is unknown, but estimates range from 0.05 percent to 2 percent. Estimates vary widely in part because many people with Tourette syndrome have very mild symptoms and may not seek medical attention. It is estimated that there are about 1,000 new cases of Tourette syndrome diagnosed in the United States every year.
Causes and symptoms
The causes of Tourette syndrome are not fully understood. Most studies agree that symptoms of Tourette syndrome involve the chemicals in the brain that help transmit information from one nerve cell in the brain to another. These chemicals are called neurotransmitters. Some studies suggest that the tics in Tourette syndrome are caused by an increased amount of a neurotransmitter called dopamine. Other studies suggest instead that there is a problem with a different neurotransmitter called serotonin. Still others believe the problem involves other chemicals required for normal functioning of the brain.
Most studies suggest that Tourette syndrome is an autosomal dominant disorder with decreased penetrance. An autosomal disorder is one that occurs because of an abnormal gene on a chromosome that is not a sex-linked chromosome. A dominant disorder means that it only takes one abnormal gene in a pair of genes to have the disorder. Parents each pass one copy of each gene to their child. Because in autosomal dominant disorders one gene is abnormal, people with this disorder have about a 50 percent chance of passing the abnormal gene to their offspring. Decreased penetrance means that not all people who inherit the abnormal gene develop symptoms. There is some evidence that females who inherit the Tourette syndrome gene have a lower probability of exhibiting symptoms than males who inherit the gene.
The principal symptoms of Tourette syndrome include simple and complex motor and vocal tics. Simple motor tics are characterized by brief muscle contractions of only one or a small number of muscle groups. An eye twitch is an example of a simple motor tic. Complex motor tics tend to appear more complicated and purposeful than simple tics and involve coordinated contractions of several muscle groups. Some examples of complex motor tics include the act of hitting oneself or jumping.
Vocal tics are actually manifestations of motor tics that involve the muscles required for producing sound. Simple vocal tics include stuttering , stammering, abnormal emphasis of part of a word or phrase, and inarticulate noises such as throat clearing, grunts, and high-pitched sounds. Complex vocal tics typically involve the involuntary expression of words. Perhaps the most striking example of this is coprolalia, the involuntary expression of obscene or socially inappropriate words or phrases, which occurs in fewer than one-third of people with Tourette syndrome. The involuntary echoing of the last word, phrase, sentence, or sound vocalized by oneself (phalilalia) or by another person or sound in the environment (echolalia) are also classified as complex tics.
The type, frequency, and severity of tics exhibited varies tremendously among individuals with Tourette syndrome. Tourette syndrome has a variable age of onset, and tics can start anytime between infancy and age 18. Initial symptoms usually occur before the early teens; the average age of onset for both males and females is approximately seven years. Most individuals with symptoms initially experience simple muscle tics involving the eyes and the head. These symptoms can progress to tics involving the upper torso, neck, arms, hands, and occasionally the legs and feet. Complex motor tics are usually the latest-onset motor tics. Vocal tics usually have a later onset than motor tics.
Not only is there extreme variability in symptoms among individuals with Tourette syndrome, but individuals commonly experience variability in type, frequency, and severity of symptoms over the course of their lifetime. Adolescents with Tourette syndrome often experience unpredictable and more severe than usual symptoms, which may be related to fluctuating hormone levels and decreased compliance in taking medications. Many people who as children have Tourette syndrome experience a decrease in symptoms or a complete end to symptoms in their adult years.
Several factors appear to affect the severity and frequency of tics. Stress appears to increase the frequency and severity of tics, while concentration on another part of the body that is not involved in a tic can result in the temporary alleviation of symptoms. Relaxation following attempts to suppress the occurrence of tics may result in an increased frequency of tics. An increased frequency and severity of tics can also result from exposure to such drugs as steroids, cocaine, amphetamines, and caffeine . Hormonal changes, such as those that occur prior to the menstrual cycle, can also increase the severity of symptoms.
Other associated symptoms
People with Tourette syndrome are more likely to exhibit non-obscene, socially inappropriate behaviors such as expressing insulting or socially unacceptable comments or performing socially unacceptable actions. It is not known whether these symptoms stem from more general dysfunction of impulse control that might be part of Tourette syndrome.
Tourette syndrome appears to also be associated with attention deficit disorder (ADD), a disorder characterized by a short attention span and impulsivity, and in some cases hyperactivity. Researchers have found that 21 to 90 percent of individuals with Tourette syndrome also exhibit symptoms of ADD.
People with Tourette syndrome are also at higher risk for having symptoms of obsessive-compulsive disorder (OCD), a disorder characterized by persistent, intrusive, and senseless thoughts (obsessions) or compulsions to perform repetitive behaviors that interfere with normal functioning. A person with OCD, for example, may be obsessed with germs and may counteract this obsession with continual hand washing. Symptoms of OCD are present in 1.9 to 3 percent of the general population, whereas 28 to 50 percent of people with Tourette syndrome have symptoms of OCD.
Self-injurious behavior (SIB) is also seen more frequently in those with Tourette syndrome. Approximately 34 to 53 percent of individuals with Tourette syndrome exhibit some form of self-injuring behavior. The SIB is often related to OCD but can also occur in those with Tourette syndrome who do not have OCD.
Symptoms of anxiety and depression are also found more commonly in people with Tourette syndrome. It is not clear, however, whether these are symptoms of Tourette syndrome or occur as a result of having to deal with the symptoms of moderate to severe Tourette syndrome.
People with Tourette syndrome may also be at increased risk for having learning disabilities and personality disorders and may be more predisposed to such behaviors as aggression, antisocial behaviors, severe temper outbursts, and inappropriate sexual behavior.
When to call the doctor
Parents should call the doctor if they notice the symptoms of Tourette syndrome. The initial tics usually initially involve the face or head, but the doctor should be consulted if any uncontrolled repetitive behavior is observed.
Tourette syndrome cannot be diagnosed through laboratory tests. Sometimes laboratory tests can be helpful, however, in ruling out other possible conditions. The diagnosis of Tourette syndrome is made by observing and interviewing the child, looking at the family's medical history, and talking to the child's family and sometimes to other caregivers. The diagnosis of Tourette syndrome is complicated by a variety of factors. The extreme range of symptoms of this disorder can make it difficult to differentiate Tourette syndrome from other disorders with similar symptoms. Diagnosis is further complicated by the fact that some tics appear to be within the range of normal behavior. For example, an individual who only exhibits such tics as throat clearing and sniffing may be misdiagnosed with a medical problem such as allergies . In addition, such bizarre and complex tics as coprolalia may be mistaken for psychotic or so-called bad behavior. Diagnosis is also made more difficult because often individuals attempt to control tics in public, and, therefore, the healthcare professional may have difficulty observing the symptoms firsthand. Although there is some disagreement over what criteria should be used to diagnose Tourette syndrome, the most common aid in the diagnosis is the DSM-IV. The DSM-IV outlines suggested diagnostic criteria for a variety of conditions, including Tourette syndrome.
DSM-IV criteria are:
- presence of both motor and vocal tics at some time during the course of the illness
- the occurrence of multiple tics nearly every day through a period of more than one year without a remission of tics for a period of greater than three consecutive months
- distress or impairment in functioning caused by symptoms
- onset occurs prior to age 18
- symptoms not due to medications or drugs and not related to another medical condition
Some physicians criticize the DSM-IV criteria, arguing that they do not include the full range of behaviors and symptoms seen in Tourette syndrome. Others criticize the criteria because they limit the diagnosis to those who experience a significant impairment, which may exclude individuals who have the syndrome but exhibit milder symptoms. For these reasons many physicians use their clinical judgment as well as the DSM-IV criteria as a guide to diagnosing Tourette syndrome.
There is no cure for Tourette syndrome. Treatment involves the control of symptoms through educational and psychological interventions and/or medications. The treatment and management of Tourette syndrome varies from patient to patient and should focus on the alleviation of the symptoms that are most bothersome to the individual or that cause the most interference with daily functioning.
Psychological and educational interventions
Psychological treatments such as counseling are not generally useful for the treatment of tics but can be beneficial in the treatment of associated symptoms such as obsessive-compulsive behavior and attention deficit disorder. Counseling may also help individuals to cope better with the symptoms of Tourette syndrome and to have more positive social interactions. Psychological interventions may also help people cope better with stressors that can normally trigger tics. The education of family members, teachers, and peers about Tourette syndrome can be helpful and may help to foster acceptance and prevent social isolation.
Many people with mild symptoms of Tourette syndrome never require medication. Those with more severe symptoms may require medication for all or part of their lifetime. As of 2004, the most effective treatment of tics associated with Tourette syndrome involved the use of drugs such as haloperidol, pimozide, sulpiride, and tiapride, which decrease the amount of dopamine in the body. Unfortunately, even at low dosages, these drugs bring a high incidence of side effects. The short-term side effects can include sedation, dysphoria, weight gain, movement abnormalities, depression, and poor school performance. Long-term side effects can include phobias , memory difficulties, and personality changes. These drugs are, therefore, better suited for short-term rather than long-term therapy.
In many cases, treatment of associated conditions such as ADD and OCD is considered more important than the tics themselves. Clonidine used in conjunction with such stimulants as Ritalin may be useful for treating people with Tourette syndrome who also have symptoms of ADD. Stimulants should be used with caution in individuals with Tourette syndrome, since they can sometimes increase the frequency and severity of tics. OCD symptoms in those with Tourette syndrome are often treated with such drugs as Prozac, Luvox, Paxil, and Zoloft.
In many cases the treatment of Tourette syndrome with medications can be discontinued after adolescence . Trials should be performed through the gradual tapering off of medications and should always be done under a doctor's supervision.
The prognosis for Tourette syndrome is fairly good. Although symptoms generally get worse during early adolescence, many people with Tourette syndrome experience a lessening of the severity of their symptoms during late adolescence and early adulthood. Approximately one third of children with Tourette syndrome will experience complete or nearly complete remission during their late adolescent and early adult years. Another third will experience a significant drop off in the severity and/or frequency of their symptoms during this time. It is difficult to tell how many children with Tourette syndrome experience complete remission over their entire adult lives, but it has been estimated to be about 8 percent. Many children who do not have complete and lasting remission will experience months or even years without significant symptoms. There does not appear to be a definite correlation between the type, frequency, and severity of symptoms and the eventual prognosis. People with Tourette syndrome who have other symptoms such as obsessive-compulsive disorder, attention deficit disorder, and self-injurious behavior usually have a poorer prognosis.
There is no known way to prevent Tourette syndrome.
Tourette syndrome does not, in itself, negatively affect intelligence or cognition. It is, however, often associated with other disorders such as obsessive-compulsive disorder and attention deficit disorder. It is also sometimes associated with learning and psychological disorders, many of which are often more debilitating than Tourette syndrome itself. Tourette syndrome does not reduce life expectancy. Children with Tourette syndrome often have problems socializing because of embarrassment over uncontrollable tics and negative reactions from parents, teachers, and peers who do not understand the disorder. Children with Tourette syndrome may need special attention to help them cope with the social implications of their disorder.
Attention deficit disorder (ADD) —Disorder characterized by a short attention span, impulsivity, and in some cases hyperactivity.
Autosomal dominant —A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of their offspring.
Coprolalia —The involuntary use of obscene language.
Copropraxia —The involuntary display of unacceptable/obscene gestures.
Decreased penetrance —Individuals who inherit a changed disease gene but do not develop symptoms.
Dysphoria —Feelings of anxiety, restlessness, and dissatisfaction.
Echolalia —Involuntary echoing of the last word, phrase, or sentence spoken by someone else.
Echopraxia —The imitation of the movement of another individual.
Neurotransmitter —A chemical messenger that transmits an impulse from one nerve cell to the next.
Obsessive-compulsive disorder —An anxiety disorder marked by the recurrence of intrusive or disturbing thoughts, impulses, images, or ideas (obsessions) accompanied by repeated attempts to supress these thoughts through the performance of certain irrational and ritualistic behaviors or mental acts (compulsions).
Phalilalia —Involuntary echoing by an individual of the last word, phrase, sentence, or sound he/she vocalized.
Tic —A brief and intermittent involuntary movement or sound.
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National Tourette Syndrome Association. 42–40 Bell Blvd., Bayside, NY 11361–2820. Web site: http://tsa-usa.org/ .
Tish Davidson, A.M.