Apr 01, 2008
Tic disorders are characterized by the persistent presence of tics, which are abrupt, repetitive involuntary movements and sounds that have been described as caricatures of normal physical acts. The best known of these disorders is Tourette's disorder, or Tourette's syndrome.
Tics are sudden, painless, nonrhythmic behaviors that are either motor (related to movement) or vocal and that appear out of context— for example, knee bends in science class. They are fairly common in childhood; in the vast majority of cases, they are temporary conditions that resolve on their own. In some children, however, the tics persist over time, becoming more complex and severe.
Tics may be simple (using only a few muscles or simple sounds) or complex (using many muscle groups or full words and sentences). Simple motor tics are brief, meaningless movements like eye blinking, facial grimacing, head jerks or shoulder shrugs. They usually last less than one second. Complex motor tics involve slower, longer, and more purposeful movements like sustained looks, facial gestures, biting, banging, whirling or twisting around, or copropraxia (obscene gestures).
Simple phonic tics are meaningless sounds or noises like throat clearing, coughing, sniffling, barking, or hissing. Complex phonic tics include syllables, words, phrases, and such statements as "Shut up!" or "Now you've done it!" The child's speech may be abnormal, with unusual rhythms, tones, accents or intensities. The echo phenomenon is a tic characterized by the immediate repetition of one's own or another's words. Coprolalia is a tic made up of obscene, inappropriate or aggressive words and statements. It occurs in fewer than 10% of people with tic disorders.
Children under the age of 10 with simple tics find them to be difficult to suppress, or control. Many older patients and children with complex tics describe feeling strong sensory urges in their joints, muscles and bones that are relieved by the performance of a motor tic in that particular body part. These patients also report inner conflict over whether and when to yield to these urges. A sensation of relief and reduction of anxiety frequently follows the performance of a tic. Unless the tic disorder is very severe, most people with tics can suppress them for varying periods of time.
Motor and vocal tics may be worsened by anxiety, stress, boredom, fatigue, or excitement. Some people have reported that tics are intensified by premenstrual syndrome, additives in food, and stimulants. The symptoms of tic disorders may be lessened while the patient is asleep. Cannabis (marijuana), alcohol, relaxation, playing a sport, or concentrating on an enjoyable task are also reported to reduce the severity and frequency of symptoms.
Tics are the core symptom shared by transient tic disorder, chronic motor or vocal tic disorder, and Tourette's disorder. It is the severity and course that distinguishes these disorders from one another. The age of onset for these disorders is between two and 15 years. In 75% of Tourette's disorder patients, the symptoms appear by age 11.
Causes and symptoms
Emotional factors were once viewed as the cause of tics, but this explanation has been largely discounted. The search for causes now focuses on biological, chemical and environmental factors. As of 2002, however, no definitive cause of tics has been discovered.
There appear to be both functional and structural abnormalities in the brains of people with tic disorders. While the exact neurochemical cause is unknown, it is believed that abnormal neurotransmitters(chemical messengers within the brain) contribute to the disorders. The affected neurotransmitters are dopamine, serotonin, and cyclic AMP. Researchers have also found changes within the brain itself, specifically in the basal ganglia (an area of the brain concerned with movement) and the anterior cingulate cortex. Functional imaging using positron emission tomography(PET) and single photon emission computerized tomography(SPECT) has highlighted abnormal patterns of blood flow and metabolism in the basal ganglia, thalamus, and frontal and temporal cortical areas of the brain. [The reader may wish to consult the "Brain" entry for a diagram of the brain's structures.]
Vulnerability to tic disorders appears to be genetic, or transmitted within families. Genetic factors are present in 75% of cases, although no single gene has been found to cause tic disorders. Researchers have not found a pattern suggesting that certain types of parenting or childhood experiences lead to the development of tic disorders, although some think that there is an interaction between genetic and environmental factors. Researchers are paying close attention to prenatal factors, which are thought to influence the development of the disorders.
In some cases, tic disorders appear to be caused or worsened by recreational drugs or prescription medications. The drugs most commonly involved are such psychomotor stimulants as methylphenidate(Ritalin); pemoline(Cylert); amphetamines; and cocaine. It is not clear whether tics would have developed anyway if stimulants had not been used. In a smaller percentage of cases, antihistamines, tricyclic antidepressants, antiseizure medications, and opioids have been shown to worsen tics.
Some forms of tic may be triggered by the environment. A cough that began during an upper respiratory infection may continue as an involuntary vocal tic. New tics may also begin as imitations of normally occurring events, such as mimicking a dog barking. How these particular triggers come to form enduring symptoms is a matter for further study.
In some cases, neuropsychiatric disorders, such as tic disorders and obsessive-compulsive disorder, have been shown to develop after streptococcal infection. No precise mechanism for this connection has been determined, although it appears to be related to the autoimmune system. There are other illness-related causes of tics, though they appear to be rare. These include the development of tics after head trauma, viral encephalitis or stroke.
The diagnostic criteria of all tic disorders specify that the symptoms must appear before the age of 18, and that they cannot result from ingestion of such substances as stimulants, or from such general medical conditions as Huntington's disease. Tic disorders can be seen as occurring along a continuum of least to most severe in terms of disruption and impairment, with transient tic disorder at one end and Tourette's disorder at the other.
Tics increase in frequency when a person is under any form of mental or physical stress, even if it is of a positive nature (excitement about an upcoming holiday, for example). Some people's tics are most obvious when the person is in a relaxed situation, such as quietly watching television. Tics tend to diminish when the person is placed in a new or highly structured situation, such as a doctor's office— a factor that can complicate diagnosis. When the symptoms of a tic are present over long time periods, they do not remain constant but will wax and wane in their severity.
Transient tic disorder occurs in approximately 4%–24% of schoolchildren. It is the mildest form of tic disorder, and may be underreported because of its temporary nature. In transient tic disorder, there may be single or multiple motor and/or vocal tics that occur many times a day nearly every day for at least four weeks, but not for longer than one year. If the criteria have been met at one time for Tourette's disorder or for chronic motor or vocal tic disorder, transient tic disorder may not be diagnosed.
Chronic motor or vocal tic disorder is characterized by either motor tics or vocal tics, but not both. The tics occur many times a day nearly every day, or intermittently for a period of more than one year. During that time, the patient is never without symptoms for more than three consecutive months. The severity of the symptoms and functional impairment is usually much less than for patients with Tourette's disorder.
For a diagnosis of Tourette's disorder, a patient must have experienced both multiple motor and one or more vocal tics at some time during the illness, though they do not have to occur at the same time. The tics occur many times a day, usually in bouts, nearly every day or intermittently for a period of more than one year. The patient is never symptom-free for more than three months at a time.
Children and adolescents with Tourette's disorder frequently experience additional problems including aggressiveness, self-harming behaviors, emotional immaturity, social withdrawal, physical complaints, conduct disorders, affective disorders, anxiety, panic attacks, stuttering, sleep disorders, migraine headaches, and inappropriate sexual behaviors.
Tics seem to worsen during the patient's adolescence, although some clinicians think that the symptoms become more problematic rather than more severe, because the patient experiences them as more embarrassing than previously. The symptoms do become more unpredictable from day to day during adolescence. Many teenagers may refuse to go to school when their tics are severe. Coprolalia often appears first in adolescence; this symptom causes considerable distress for individuals and their families.
Behavioral problems also become more prominent in adolescence. There is some evidence that temper tantrums, aggressiveness, and explosive behavior appear in preadolescence, intensify in adolescence, and gradually diminish by early adulthood. Interestingly, aggression appears to increase at approximately the same time that the tics decrease in severity.
Tourette's disorder is three to four times more common in males than females. Tic disorders have been reported in people of all races, ethnic groups, and socioeconomic classes. Tic disorders appear to occur more frequently in Caucasians than African Americans.
There are no diagnostic laboratory tests to screen for tic disorders. Except for the tics, the results of the patient's physical and neurological examinations are normal. The doctor takes a complete medical history including a detailed account of prenatal events, birth history, head injuries, episodes of encephalitis or meningitis, poisonings, and medication or drug use. The patient's developmental, behavioral, and academic histories are also important.
There is an average delay of five to 12 years between the initial symptoms of a tic disorder and the correct diagnosis. This delay is largely related to the misperception that tics are caused by anxiety and should be treated by psychotherapy. This misperception in turn is fueled by the fact that tics tend to increase in severity when the affected person is angry, anxious, excited or fatigued. It is also common for the patient to manifest fewer tics in a doctor's office than at home, leaving parents feeling frustrated and undermined and physicians confused. In addition, children quickly learn to mask their symptoms by converting them to more socially acceptable movements and sounds. The diagnosis of a tic disorder can be aided in some cases by directly observing, videotaping or audiotaping the patient in a more natural setting.
Clinicians can also become confused by such additional symptoms of tic disorders as touching, hitting, jumping, smelling hands or objects, stomping, twirling and doing deep knee bends. They disagree, however, as to whether such symptoms should be classified as tics or compulsions. There appears to be a significant overlap between the symptoms of tic disorders and those of obsessive-compulsive disorder (OCD).
Abnormal obsessive-compulsive behavior has been found in 40% of patients with Tourette's disorder between the ages of six and 10 years. Obsessions are persistent ideas, thoughts, impulses, or images that are experienced as intrusive, inappropriate, senseless, and repetitive. Compulsions are defined as repetitive behaviors performed to reduce the anxiety or distress caused by the obsessions. For those diagnosed with OCD, common obsessions have to do with dirt, germs, and contamination. Patients with Tourette's disorder often have obsessions that involve violent scenes, sexual thoughts, and counting; their compulsions are often related to symmetry (lining things up and getting them "just right," for example). OCD symptoms occur considerably later than tics, and appear to worsen with age. Some theorists have suggested that obsessive thoughts are cognitive tics.
Tic disorders can be differentiated from movement disorders by the following characteristics: they are suppressible; they tend to persist during sleep; they are preceded by sensory symptoms; they have both phonic and motor components; and they wax and wane.
Children and adults with tic disorders are at increased risk for depression and other mood disorders, as well as anxiety disorders. This comorbidity may be due to the burden of dealing with a chronic, disruptive, and often stigmatizing disorder. The energy and watchfulness required to suppress tic symptoms may contribute to social anxiety, social withdrawal, self-preoccupation, and fatigue. Low self-esteem and feelings of hopelessness are common in patients diagnosed with tic disorders.
While OCD behaviors have been noted in as many as 80% of individuals with tic disorders, only 30% meet the full criteria for OCD. Distinguishing complex tics from simple compulsions can be difficult. Touching compulsions appear to be characteristic of the tic-related type of OCD. Compared to obsessive-compulsive disorder in persons without a history of tics, there will likely be an earlier age of onset, a greater proportion of males, a more frequent family history of chronic tics, and a poorer therapeutic response to selective serotonin reuptake inhibitors (SSRIs)— although the addition of a neuroleptic to the treatment regimen sometimes brings about improvement.
As many as 50%–80% of children with Tourette's disorder have some symptoms of attention-deficit/hyperactivity disorder(ADHD), including a short attention span, restlessness, poor concentration, and diminished impulse control. On average, ADHD will manifest two and a half years before the tics appear. A dual diagnosis of ADHD and tic disorder is associated with more severe tics and greater social impairment than for tic disorder by itself. Over time, the problems caused by the inattention, impulsivity, motor overactivity and the resultant underachievement in school associated with ADHD are often more disabling than the tics themselves.
Children with tic disorders are five times as likely as other children to require special education programs. The tics may be disruptive and mistakenly interpreted by teachers as intended to disturb the class. Often, children with tic disorders have underlying learning disabilities as well. While there does not appear to be any impairment in general intellectual functioning, researchers have identified patterns of specific learning problems in children with tic disorders. These problems include abnormal visual-perceptual performance, reduced visual-motor skills, and discrepancies between verbal and performance IQ. Many of these learning difficulties are also commonly found in children with ADHD.
Increasing numbers of children with tic disorders are also diagnosed with a conduct disorder. Children with conduct disorder show inappropriate and sometimes severe aggression toward people and animals. They may also act out other destructive impulses. Unfortunately, some of these children grow up to develop a personality disorder.
A holistic approach is recommended for the treatment of tic disorders. A multidisciplinary team should work together with the affected child's parents and teachers to put together a comprehensive treatment plan. Treatment should include the following:
Educating the patient and family about the course of the disorder in a reassuring manner.
Completion of necessary diagnostic tests, including self-reports (by child and parents); clinician-administered ratings; and direct observational methods.
Comprehensive assessment, including the child's cognitive abilities, perception, motor skills, behavior and adaptive functioning.
Collaboration with school personnel to create a learning environment conducive to academic success.
Therapy, most often behavioral or cognitive-behavioral, though other modalities may be appropriate.
If necessary, evaluation for medication.
Behavioral and cognitive-behavioral therapy
Massed negative practice has been one of the most frequently used behavioral therapy techniques in the treatment of children with tic disorder. The patient is asked to deliberately perform the tic movement for specified periods of time interspersed with brief periods of rest. Patients have shown some decrease in tic frequency, but the long-term benefits of massed negative practice are unclear.
Contingency management is another behavioral treatment. It is based on positive reinforcement, usually administered by parents. Children are praised and rewarded for not performing tics and for replacing them with alternative behaviors. Contingency management, however, appears to be of limited use outside of such controlled settings as schools or institutions.
Self-monitoring consists of having the patient record tics by using a wrist counter or small notebook. It is fairly effective in reducing some tics by increasing the child's awareness.
Habit reversal is the most commonly used technique, combining relaxation exercises, awareness training, and contingency management for positive reinforcement. This method shows a 64%–100% success rate.
Adding a cognitive component to habit reversal involves the introduction of flexibility into rigid thinking, and confronting the child's irrational expectations and unrealistic anticipations. It has not been shown as of 2002 to increase treatment effectiveness. The specific cognitive technique of distraction, however, has been shown to help patients resist sensory urges and to restore the patient's sense of control over the tic.
Medication is the main treatment for motor and vocal tics. Patients and their families, however, should be evaluated fully and use other treatment methods in conjunction with medication. Because the symptoms of tic disorders overlap those of OCD and ADHD, it is essential to determine which symptoms are causing the greatest concern and impairment, and treat the patient according to the single diagnostic category that best fits him or her, whether it is a tic disorder, OCD, or ADHD.
Medications prescribed for patients with tic disorders include:
Typical neuroleptics (antipsychotic medications), including haloperidol(Haldol) and pimozide(Orap). Neuroleptics can have significant side effects, which include concentration problems, cognitive blunting, and rarely, tardive dyskinesia(a movement disorder that consists of lip, mouth, and tongue movements). Such side effects as stiffness, rigidity, tremor, sedation, and depression are common with haloperidol, but are less so with pimozide.
Alpha-adrenergic receptor agonists, including clonidine(Catapres) and guanfacine (Tenex). Clonidine has fewer and milder side effects than the neuroleptics in general, with the most common being sedation. Sedation occurs in 10%–20% of cases and can often be controlled through adjusting the dosage.
The phenothiazines may be used when haloperidol or pimozide has proven ineffective.
Atypical antipsychotics and other agents that block dopamine receptors include risperidone(Risperdal) and clozapine(Clozaril).
Tetrabenazine is a promising new medication with fewer side effects than other typical neuroleptics. It can be used in combination with the older antipsychotic medications, allowing for lower doses of both medications with substantial relief.
Selective serotonin reuptake inhibitors (SSRIs), which include such medications as fluoxetine(Prozac) and sertraline(Zoloft), can be used to treat the obsessive-compulsive behaviors associated with Tourette's disorder. They can also be helpful with depression and impulse control difficulties, though they must be given at higher dosages for OCD than for depression. The SSRIs, however, can cause gastric upset and nausea.
Benzodiazepines are used in some cases to lower the patient's anxiety level, but are often avoided because they can cause dependence and tolerance.
Nicotine chewing gum appears to reduce tics when added to ongoing treatment with haloperidol, but is in need of further study.
There is growing interest in dietary changes and nutritional supplements to prevent and manage the symptoms of tic disorders, although formal studies have not yet been conducted in this area. Some theorists have suggested that hidden food and chemical allergies or nutritional deficiencies may influence the development and maintenance of tic disorders. Recommendations include eating organic food and avoiding pesticides; taking antioxidants; increasing intake of folic acid and the B vitamins; eating foods high in zinc and magnesium; eliminating caffeine from the diet; and avoiding artificial sweeteners, colors and dyes.
There is presently no cure for tic disorders, and there is no evidence that early treatment alters prognosis. When a child is first evaluated, it is not possible to determine whether the tics will be chronic or transient, mild or severe.
As recently as twenty years ago, tic disorders were considered to be lifelong conditions, with remissions believed to be rare. There is now a general consensus that if a tic disorder is the only diagnosis, the prognosis is favorable. Up to 73% of patients report that their tics decreased markedly or disappeared as they entered the later years of adolescence or early adulthood.
In a small number of patients, the most severe and debilitating forms of a tic disorder occur in adult life. In addition, stress in later life can cause tics to re-emerge. In rare cases, the tics may be new developments in adulthood, though this phenomenon may be more common than previously thought. Remission rates for tic disorders are difficult to pinpoint among this seldom-studied population, but appear to be extremely low.
While the tics themselves may decline, however, the associated problems often continue into adult life. Obsessive-compulsive symptoms and other behavioral problems, as well as learning disabilities, may grow worse. Obsessive-compulsive behaviors become most pronounced at age 15 and remain at that level. Panic attacks, depression, agoraphobia and alcoholism are most significant in the early adult years, while a tendency toward obesity increases steadily with age, particularly in women.
In adulthood, a patient's repertoire of tics is reduced and becomes predictable during periods of fatigue and heightened emotionality. Some studies suggest remission rates, with the complete cessation of symptoms, to be as high as 50%. Cases of total remission appear to be related to the family's treatment of the patient when he or she was a child. Persons who were punished, misunderstood and stigmatized experience greater functional impairment as adults than those who were supported and understood as children.
There are few preventive strategies for tic disorders. There is some evidence that maternal emotional stress during pregnancy and severe nausea and vomiting during the first trimester may affect tic severity. Attempting to minimize prenatal stress may possibly serve a limited preventive function.
Similarly, because people with tic disorders are sensitive to stress, attempting to maintain a low-stress environment can help minimize the number or severity of tics (reducing the number of social gatherings, which can be anxiety-provoking, for example). This approach cannot prevent tics altogether, and must be undertaken with an awareness that it is neither healthful nor advisable to attempt to eliminate all stressful events in life.
See also Abnormal Involuntary Movement Scale; Neuropsychological testing;