A tic is a nonvoluntary body movement or vocal sound that is made repeatedly, rapidly, and suddenly. It has a stereotyped but nonrhythmic character. The child or adolescent with a tic experiences it as irresistible but can suppress the movement or noise for a period of time. Tics are categorized as motor or vocal, and as simple or complex. The word "tic" itself is French.
Tics are a type of dyskinesia, which is the general medical term given to impairments or distortions of voluntary movements. Although tics vary considerably in severity, they are associated with several neuropsychiatric disorders in children and adolescents. The American Psychiatric Association (APA) defined four tic disorders in the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders , or DSM-IV . The disorders are distinguished from one another according to three criteria: the child's age at onset; the duration of the disorder; and the number and variety of tics.
- Transient tic disorder (also known as benign tic disorder of childhood): The criteria for transient tic disorder specify that the onset must occur before the age of 18 years; the tics must occur many times a day almost every day for at least four weeks but not longer than 12 months; and the child must not meet the criteria for Tourette syndrome or chronic tic disorder.
- Chronic motor or vocal tic disorder: To meet the diagnosis of chronic tic disorder, the child must be younger than 18 years of age; the tics must have occurred nearly every day or intermittently for a period longer than a year, without a tic-free interval longer than three months; the tics must be either vocal or motor but not both; and the child must not meet the criteria for Tourette disorder.
- Tourette disorder (also known as Tourette syndrome, or TS): Tourette disorder is considered the most serious of the four tic disorders. The DSM-IV criteria for Tourette disorder specify that the child must be younger 18 years of age at onset; the tics must include multiple vocal as well as motor tics, although not necessarily at the same time; the tics must occur many times a day, nearly every day or at intervals over a period longer than a year, without symptom-free intervals longer than six months; there must be variations in the number, location, severity, complexity, and frequency of the tics over time; and the tics cannot be attributed to the effects of a substance (such as stimulants) or a disease of the central nervous system.
- Tic disorder not otherwise specified: This category includes all cases that do not meet the full criteria for any of the other tic disorders.
Tics most commonly affect the child's face, neck, voice box, and upper torso but may involve almost any body part. The experience of having a tic is difficult to describe to those who have never been troubled by them. Having tics may be compared to having the sensation of having to cough because something is tickling one's throat or nose. The sensation is irresistible and immediate.
Simple tics involve only a few muscles or sounds that are not yet words. Examples of simple motor tics include nose wrinkling, facial grimaces, eye blinking, jerking the neck, shrugging the shoulders, or tensing the muscles of the abdomen. Simple vocal tics include grunting, clucking, sniffing, chirping, or throat-clearing noises. Simple tics rarely last longer than a few hundred milliseconds.
Complex tics involve multiple groups or muscles or complete words or sentences. Examples of complex motor tics include such gestures as jumping, squatting, making motions with the hands, twirling around when walking, touching or smelling an object repeatedly, and holding the body in an unusual position. Complex motor tics last longer than simple motor tics, usually several seconds or longer. Two specific types of complex motor tics that often cause parents concern are copropraxia , in which the tic involves a vulgar or obscene gesture, and echopraxia , in which the tic is a spontaneous imitation of someone else's movements.
Similarly, complex vocal tics involve full speech and language, which may range from the spontaneous utterance of individual words or phrases, such as "Stop," or "Oh boy," to speech blocking or meaningless changes in the pitch, volume, or rhythm of the child's voice. Specific types of complex vocal tics include palilalia , which refers to the child's repetition of his or her own words; coprolalia , which refers to the use of obscene words or abusive terms for certain racial or religious groups; and echolalia , in which the child repeats someone else's last word or phrase.
Sensory tics are less common than either motor or vocal tics. The term refers to repeated unwanted or uncomfortable sensations, usually in the child's throat, eyes, or shoulders. The child may feel a sensation of tickling, warmth, cold, or pressure in the affected area.
Phantom tics are the least common type of tic. A phantom tic is an out-of-body variation of a sensory tic in which the person feels a sensation in other people or objects. People with phantom tics experience temporary relief from the tic by touching or scratching the object involved.
Other features of tics
Tics typically occur in bouts or episodes alternating with periods of tic-free behavior lasting from several seconds to several hours. They generally diminish in severity when the child is involved in an absorbing activity such as reading or doing homework, and increase in frequency and severity when the child is tired, ill, or stressed. Some children have tics during the lighter stages of sleep or wake up during the night with a tic.
Severe complex motor tics carry the risk of physical injury, as the child may damage muscles or joints, fracture bones, or fall down during an episode of these tics. Some children harm themselves deliberately by self-cutting or self-hitting, while others hurt themselves unintentionally by touching or handling lighted matches, razor blades, or other dangerous objects. Severe complex vocal tics may interfere with breathing or swallowing.
Tics as such are symptoms and are not transmitted directly from one person to another. Tic disorders , however, are known to run in families. In addition, some doctors think that tic disorders are more likely to develop in children who have had certain types of infections. These theories are discussed more fully below.
Prevalence of tic disorders
The statistics given for tics and tic disorders vary from source to source, in part because tics vary considerably in severity, and many children with mild tics may never come to a doctor's attention. Estimates for the general North American population range from 3 to 20 percent for transient tics (particularly among children below the age of ten); 2–5 percent for chronic tic disorders; and 0.1–0.8 percent for Tourette syndrome. A Swedish study done in 2003 reported that 6.6 percent of a sample of Uppsala school children between the ages of 7 and 15 met DSM-IV criteria for tic disorders: 4.8 percent for transient tic disorder, 0.8 percent for chronic motor tic disorder, 0.5 percent for chronic vocal tic disorder, and 0.6 percent for Tourette syndrome. One study of American volunteers for military service reported a prevalence of 0.5 cases of TS per 1000 for males and 0.3 cases per 1000 for females. Tourette syndrome is known to be more common in males than in females, although the gender ratio is variously reported as 3: 1, 5: 1, or even 10: 1.
Little is known as of 2004 about the prevalence of tic disorders across racial or ethnic groups. One small study that was done in western North Carolina reported that Caucasian children were slightly more likely to have tic disorders than either African American or Native American children (2.1 percent to 1.5 percent and 1.5 percent respectively). The authors of the study cautioned, however, against applying their findings to larger groups of children in other parts of the United States.
Tic disorders and comorbid disorders
One important characteristic of tics and tic disorders is that they rarely occur by themselves. Tic disorders—particularly TS—have a high rate of comorbidity with other childhood disorders. The term comorbid is used to refer to a disease or disorder that occurs at the same time as another disorder. The frequencies of the most common disorders that may be comorbid with tic disorders and Tourette syndrome are as follows:
- attention-deficit/hyperactivity disorder (ADHD): 50 percent comorbidity with tic disorders, 90 percent comorbidity with TS
- obsessive-compulsive disorder (OCD): 11 percent and 80 percent respectively
- major depression: 40 percent and 44 percent respectively
Causes and symptoms
The causes of tics and tic disorders are not fully understood as of the early 2000s, but most researchers believe that they are multifactorial, or the end result of several causes. In the early twentieth century, many doctors influenced by Freud thought that tics were caused by hysteria or other emotional problems, and treated them with psychoanalysis. Psychoanalytic treatment, however, had a very low rate of success.
Since the 1970s, researchers have been looking at genetic factors in tic disorders and Tourette syndrome. With regard to TS, genetic factors are present in about 75 percent of children diagnosed with TS, with 25 percent having inherited genetic factors from both parents. The exact pattern of genetic transmission was not known as of 2004, however; autosomal dominant, autosomal recessive, and sex-linked inheritance patterns have all been studied and rejected. Some candidate genes for TS have also been tested and excluded. What is known is that the patient's environment and heredity play a significant part in the severity and course of TS.
Tic disorders as well as OCD sometimes develop after infections (usually scarlet fever or strep throat ) caused by a group of bacteria known as group A beta-hemolytic streptococci, sometimes abbreviated as GABHS. These disorders are sometimes grouped together as PANDAS disorders, which stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococci. Some researchers think that the tics develop when antibodies in the child's blood produced in response to the bacteria cross-react with proteins in the brain tissue. The connection between streptococcal infections and tic disorders is questioned by some researchers, however, on the grounds that most children have a GABHS infection at some point in their early years, but the vast majority (95 percent) do not develop OCD or a tic disorder. There appears to be a closer connection between Sydenham's chorea, which is a movement disorder, and GABHS infections than between tic disorders and these infections. One prospective study done at Yale reported in 2004 that new GABHS infections do not appear to cause a worsening of tics in children diagnosed with OCD or Tourette syndrome.
Neuroimaging studies have shown that tic disorders are related to abnormal levels of neurotransmitters known as dopamine, serotonin, and cyclic AMP in certain parts of the brain. A neurotransmitter is a chemical produced by the body that conveys nerve impulses across the gaps (synapses) between nerve cells. In addition to abnormalities in the production or absorption of these chemical messengers, imaging studies indicate that the blood flow and metabolism in a part of the brain called the basal ganglia are abnormally low. The basal ganglia are groups of nerve cells deep in the brain that control movement as well as emotion and certain aspects of thinking. In contrast to the low level of blood flow in the basal ganglia, the motor areas in the frontotemporal cortex of the brain show increased levels of activity.
The various types of tics themselves have already been described. Other symptoms that may be associated with tics and tic disorders include obsessive thoughts; difficulty concentrating or paying attention in school; forgetfulness; slowness in completing tasks; losing the thread of a conversation. These symptoms are usually regarded as side effects of interrupted thinking or behavior caused by the tics.
When to call the doctor
Most cases of mild tics do not require medical treatment and will clear up on their own over time. Doctors usually recommend that family members try to ignore simple tics, since teasing or other unwanted attention may make the tics worse. A visit to the doctor is recommended, however, under any of the following circumstances:
- The child is falling behind in school because of the tics.
- The child's relationships with peers and adults outside the family are affected by the tics.
- The child cannot carry out activities of daily living (self-feeding, bathing, getting dressed, etc.).
- The child has fallen, injured himself, or developed other physical problems because of the tics.
- Other family members have or have had tic disorders.
- The child has recently had an episode of strep throat or other streptococcal infection.
- The child has been diagnosed with OCD, ADHD, or depression.
- The tics have come on suddenly.
Tic disorders are diagnosed by a process of excluding other possibilities; there are no definitive tests for these disorders as of the early 2000s. For this reason, the diagnosis of tic disorders is often delayed or sometimes missed altogether in milder cases. One study reported an average delay of five to 12 years between the initial symptoms and the correct diagnosis. In addition, diagnosis is complicated by the fact that children often learn to mask their tics by converting them to more socially acceptable or apparently voluntary movements or sounds.
History and physical examination
The first part of a medical workup for tics is the taking of a medical history and a general physical examination. The doctor will want to know whether there is a family history of tics or tic disorders, whether the child has been diagnosed with other childhood developmental or psychiatric disorders, and whether he or she has recently had strep throat or a similar infection.
The physical examination helps the doctor rule out such other possible diagnoses as Sydenham's chorea, a self-limited movement disorder that most commonly affects children between five and 15 years of age; other movement disorders ; seizure disorders; encephalitis ; neurosyphilis; Wilson's disease (a rare inherited disease that causes the body to retain copper); schizophrenia ; carbon monoxide poisoning ; cocaine intoxication; brain injuries caused by trauma; cerebral palsy ;or the side effects of certain medications, particularly stimulants and antiepileptic drugs.
The doctor may not be able to observe the tic(s) during the child's first office visit, often because the child has learned to suppress or mask them. In some cases, a follow-up visit may be scheduled, or the doctor may refer the child to a child psychiatrist or neurologist for further observation. Another approach that can be used to confirm the diagnosis is to audiotape or videotape the child at home or in another less stressful setting.
Most child psychiatrists will administer the Yale Global Tic Severity Scale (YGTSS) during the intake interview and at follow-up visits in order to identify the particular tic disorder affecting the child, identify comorbid disorders if present, evaluate the severity of the tics, and monitor the child's response to treatment.
The YGTSS, which was first published in 1989, is a semi-structured interview that is widely used by researchers who study tic disorders. "Semi-structured" means that it is an open-ended set of questions that allow the child's parents to describe the tics and other symptoms in detail rather than just answer brief yes-or-no questions.
As mentioned earlier, there are no laboratory tests to diagnose tics as such. In some cases, however, the doctor may order a blood test to rule out Wilson's disease or other metabolic disorders, or order a throat culture if the child has recently had strep throat. If the doctor suspects that the child has a PANDAS disorder, he or she may order a blood test to measure the level of antibodies against group A streptococci.
As of 2004, imaging studies were not routinely performed on children or adolescents with tics unless the doctor suspects a brain injury, infection, or structural abnormality. Magnetic resonance imaging (MRIs), PET scans, and single-photon emission computed tomography (SPECT) scans have been used by researchers, however, to study the brains of patients diagnosed with Tourette syndrome.
In the summer of 2004, two engineers in Taiwan reported on the development of a computerized diagnostic system that will allow radiologists to use SPECT imaging to distinguish between chronic tic disorder and Tourette syndrome with a much higher degree of accuracy. The system appears to be potentially useful in speeding up the process of diagnosis and allowing earlier treatment of TS.
After psychoanalysis was discredited in the 1970s as a treatment for tic disorders, some doctors urged using such antipsychotic drugs as haloperidol (Haldol) to treat TS by suppressing the tics. These drugs, which are sometimes called neuroleptics, have severe side effects and are likely to interact with other medications that the child may be taking. In addition, tics are increasingly recognized as complex phenomena that have an emotional as well as a physical dimension. As a result, the treatment of tic disorders has changed in the early 2000s in the direction of minimizing the use of medications in favor of a multidisciplinary approach.
The approach to assess a child with a tic disorder is as follows:
- Administer the YGTSS in order to evaluate the areas of the child's functioning that are most severely affected by the tics.
- Identify any comorbid disorders if present. In many cases, the tics do not interfere with the child's life as much as ADHD, OCD, or depression. ADHD should be the primary target of management in children diagnosed with a tic disorder and comorbid ADHD.
- Rank the symptoms in order of importance in order to focus treatment on the ones that are most significant to the child and the family.
- Emphasize controlling the tics and learning to live with them rather than trying to eliminate them with drugs.
- Use behavioral and psychotherapeutic approaches as well as medications.
- Involve the patient's teachers and other significant adults as well as parents in order to help monitor the child's symptoms and response to treatment.
There is no medication that can cure a tic disorder; all drugs that are used to treat these disorders as of the early 2000s are used only to manage tics. In general, doctors prefer to avoid medications in treating mild tics; start the treatment of moderate or severe tics with medications that have relatively few side effects, and prescribe stronger drugs only when necessary.
Children whose throat cultures or blood tests are positive for a GABHS infection are treated aggressively with antibiotics , most commonly penicillin V.
Psychotherapy for tics and tic disorders typically involves education about tic disorders and therapy for the family as well as individual treatment for the child. The American Academy of Child and Adolescent Psychiatry (AACAP) urges parents to avoid blaming or punishing the child for the tics, as shaming or harsh treatment increases the child's level of emotional stress and usually makes the tics worse.
Cognitive-behavioral approaches are the most common type of individual psychotherapy used to treat tics and tic disorders. Specific behavioral approaches include the following:
- Massed negative practice: In this form of behavioral treatment, the child is asked to perform the tic intentionally for specified periods of time interspersed with rest periods.
- Competing response training: This is a form of treatment of motor tics in which the child is taught to make the opposite movement to the tic.
- Self-monitoring: In awareness training, the child keeps a diary, small notebook, or wrist counter for recording tics. It is supposed to reduce the frequency of tic bouts by increasing the child's awareness of them.
- Contingency management: This approach works best in the home and is usually carried out by the parents. The child is praised or rewarded for not performing the tics and for replacing them with acceptable alternative behaviors.
As of the early 2000s, however, no controlled studies have been done comparing the effectiveness of these various behavioral approaches. At best, they appear to produce mixed results.
Surgery is used very rarely to treat tic disorders; it is usually tried only if the tic has not responded to any medication and interferes significantly with the patient's life. Some patients with TS, however, have been successfully treated with stereotactic surgery involving high-frequency stimulation of the thalamus. Stereotactic surgery involves an approach that calculates angles and distances from the outside of the patient's skull to locate very small lesions or structures deep inside the brain. It allows the surgeon to remove tissue or treat injured areas through much smaller incisions.
The place of alternative or complementary therapies in treating tics is debated. One group of Chinese physicians reported successfully treating patients diagnosed with TS with acupuncture. However, a group of researchers studying traditional medicine in Bali found it ineffective in treating tic disorders, and a second group at Johns Hopkins reported that relaxation therapy did not have a statistically significant effect in treating children diagnosed with TS. There is also some evidence that gingko, ginseng, and some other herbs taken for their stimulant effects may increase the severity of tics in children and adolescents.
Although some nutritionists have suggested a possible connection between sugar or food coloring and tic severity, no studies published as of 2004 had demonstrated such a connection. One study done at the University of Kansas did find a connection between caffeine (which is found in cola beverages and some other soft drinks as well as tea and coffee) consumption and tic severity in children. The study sample, however, was quite small.
The prognosis for most tics and tic disorders is quite good. In the majority of cases, the tics diminish in severity and eventually disappear as the child grows older. Even in Tourette syndrome, about 85 percent of children find that their tics diminish or go away entirely during or after adolescence . Tics that persist beyond the teenage years, however, usually become permanent.
Factors associated with a poorer prognosis for all tic disorders include the following:
- history of complications during the child's birth
- chronic physical illness in childhood
- physical or emotional abuse in the family or a history of family instability
- exposure to anabolic steroids or cocaine
- comorbid psychiatric or developmental disorders
There are no known ways to prevent either tics or tic disorders.
In some cases, parents may find it helpful to monitor the child's intake of cola, iced tea, other drinks containing caffeine, and certain herbal teas.
Parental concerns related to tics and tic disorders are difficult to address in general terms, because tics can range in type and severity from simple noises or movements of short duration that do not attract much attention from others to complex tics of a physically harmful or socially embarrassing nature that attract a lot of attention. In addition, tics must often be managed in the context of another disorder affecting the child. Since the treatment of tics is individualized, it is best for parents to consult with the child's doctor(s) regarding special educational programs or settings, explaining the tics or tic disorder to others, dealing with the side effects of medications, and managing rage attacks or other symptoms that may be associated with the tics.
Basal ganglia —Brain structure at the base of the cerebral hemispheres involved in controlling movement.
Chorea —Involuntary movements in which the arms or legs may jerk or flail uncontrollably.
Comorbidity —A disease or condition that coexists with the disease or condition for which the patient is being primarily treated.
Compulsion —A repetitive or ritualistic behavior that a person performs to reduce anxiety. Compulsions often develop as a way of controlling or "undoing" obsessive thoughts.
Coprolalia —The involuntary use of obscene language.
Copropraxia —The involuntary display of unacceptable/obscene gestures.
Dopamine —A neurotransmitter made in the brain that is involved in many brain activities, including movement and emotion.
Dyskinesia —Impaired ability to make voluntary movements.
Echolalia —Involuntary echoing of the last word, phrase, or sentence spoken by someone else.
Echopraxia —The imitation of the movement of another individual.
Multifactorial —Describes a disease that is the product of the interaction of multiple genetic and environmental factors.
Neuroleptic —Another name for the older type of antipsychotic medications, such as haloperidol and chlorpromazine, prescribed to treat psychotic conditions.
Neurotransmitter —A chemical messenger that transmits an impulse from one nerve cell to the next.
Palilalia —A complex vocal tic in which the child repeats his or her own words, songs, or other utterances.
PANDAS disorders —A group of childhood disorders associated with such streptococcal infections as scarlet fever and strep throat. The acronym stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococci.
Semi-structured interview —A psychiatric instrument characterized by open-ended questions for discussion rather than brief questions requiring yes or no answers.
Stereotactic technique —A technique used by neurosurgeons to pinpoint locations within the brain. It employs computer imaging to guide the surgeon to the exact location for the surgical procedure.
Stereotyped —Having a persistent, repetitive, and senseless quality. Tics are stereotyped movements or sounds.
Streptococcus —Plural, streptococci. Any of several species of spherical bacteria that form pairs or chains. They cause a wide variety of infections including scarlet fever, tonsillitis, and pneumonia.
Tic —A brief and intermittent involuntary movement or sound.
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Rebecca Frey, PhD