What are tics? |

Causes and Symptoms

Tics are small, inappropriate, involuntary, compulsive jerking or twitching movements that recur uncontrollably and appear to be nonrhythmic (erratic) in pattern. Tics are stereotyped movements of small portions of the body that last only briefly but may be repeated often. They are often set off by psychologically stressful events. In many cases, tics can be voluntary and temporarily suppressed, but often with the result that the same movements occur more forcefully afterward. The term “habit spasm” is often used for tics that occur among children. A tic is a symptom rather than a disease. Many tics are believed to be of psychogenic origin, and certain others seem to be related to epilepsy, encephalitis, or diseases of unknown origin.

Motor tics commonly involve coarse muscle movements of small magnitude, including movements of the face (such as eye blinks, grimaces, or sniffing movements), shrugging of the shoulders, jerks of the neck, or twitches of the body parts. Many motor tics (and also vocal tics) are easily imitated by others but are performed involuntarily and uncontrollably by the patient. Distracting the patient’s attention may stop certain tics. In most cases, the tic does not interfere with the patient’s use of the hands or feet, even in delicate movements. Several neurologists distinguish simple motor tics (eye winking, head twitching, shoulder shrugs, or facial grimaces) from complex motor tics using more muscles and requiring coordination. Complex motor tics may include touching oneself or other people, jumping, hitting, or throwing things.

Vocal or phonic tics include the making of sounds, which may include grunts, coughs, sniffs, clearings of the throat, animal noises (especially barking and yelping), or understandable words. The words may simply be repeated utterances of the patient’s own words (palilalia), repetition of words spoken to the patient (echolalia), or obscene and offensive words (coprolalia). Although coprolalia is one of the more striking symptoms of Tourette’s syndrome and has been vividly portrayed in many popular accounts of this disorder, it is usually a mild or transient symptom and appears in only a minority of cases.

Sensory tics are unusual sensations of pressure, cold, warmth, tickling, or other common sensations that are generally brief in duration. Some otherwise inexplicable movements may be interpreted as actions taken by the patient to alleviate these sensory tics. Sensory tics are reported to be present in about 40 percent of patients with Tourette’s syndrome.

Tic disorders can be classified into four types: tic douloureux, transient tic disorder of childhood, chronic tic disorder, and Tourette’s syndrome. One of the most common forms of tic is trigeminal neuralgia, also called tic douloureux, a disorder that affects about fifteen thousand individuals annually in the United States. Tic douloureux is a disorder of the trigeminal or fifth cranial nerve, the nerve that supplies motor stimulation to the jaw muscles and sensory innervation to much of the skin of the face. Tic douloureux usually begins with a very brief but very intense, sharp pain, often described as feeling like an electric shock or a stabbing, swiftly spreading in many cases along the course of the affected nerve. The pain is usually accompanied by uncontrolled spasms or paroxysms that last less than a second but continue to recur for several minutes. These episodes may be separated from one another by tic-free periods lasting from weeks to more than a year. The pain and twitching are generally confined to one side of the face, often to one of the three divisions of the trigeminal nerve, usually the maxillary or mandibular division, or, much less often, the ophthalmic division. In addition to the uncontrollable tics, patients suffering from tic douloureux
often wince visibly from the pain; this habit is responsible for the term “tic douloureux,” meaning “painful tic.”

The immediate event precipitating an attack of tic douloureux is usually a mild stimulation or irritation of a “trigger zone” on or about the face, lips, tongue, or gums. The trigger zone is often a small area that is constant for a particular patient; some patients can trigger an episode by stimulating the trigger zone themselves. The most common locations for the trigger zone are along the cheek or the attached parts of the lips; less common locations include the gums or the floor of the mouth beside the tongue. Some patients suffering an attack of tic douloureux will apply pressure to their faces, but the pain usually goes away by itself. Attacks generally occur during the day rather than at night, and they typically increase in intensity and become more frequent and exhausting to the patient until treatment is sought.

The stimulus that normally evokes an attack of tic douloureux may be an exposure to touch or pressure, to cold, to food in the mouth, or even to a puff of air. Because an attack can be precipitated by touching or otherwise stimulating the trigger zone, many victims of tic douloureux avoid touching the region in which the trigger zone is located. When the trigger zone is on the outside of the face, patients may become very fearful of touching the affected part, and men may avoid shaving. Some patients avoid brushing their teeth and remain unwashed for weeks or even months in the vicinity of their trigger area, with social consequences that often contribute to pessimistic feelings and even depression.

When tongue or cheek movements precipitate attacks, patients suffering from tic douloureux may develop the habit of holding the affected side of their face motionless, which sometimes restricts talking, eating, or similar everyday movements. In some cases, certain chewing movements or the presence of food in certain locations in the mouth may precipitate an attack; in these cases, patients are often very careful to avoid eating or chewing on the affected side, and in extreme cases they may so often avoid eating or drinking that they become dehydrated and emaciated. Some physicians advise such patients to modify their diet and drink only liquids, fortified with vitamins, that can be consumed without chewing. Malnutrition and physical inactivity are in many cases reinforced by the social consequences of facial uncleanliness and lack of hygiene, or by the fear of such consequences. The lack of social contact may result in pessimistic or negative feelings, feelings of inadequacy or lack of worth, preoccupation with loss and with past events, feelings of rejection or powerlessness, and other symptoms of clinical depression in many patients.

Dental disease or trauma may sometimes be associated with tic douloureux, but in most cases the tic has no apparent cause. Tic douloureux is more common after the age of forty and is slightly more common in women than in men. Some researchers believe that infection with a herpesvirus (especially herpes simplex) may be causally related to trigeminal neuralgia, but other researchers doubt this connection. Tumors of the trigeminal (Gasserian) ganglion, brain-stem tumors, multiple sclerosis, or localized damage to the brain stem tissue can sometimes give rise to conditions that closely resemble tic douloureux, but the majority of tics occur among patients having none of these conditions.

The remaining forms of tic disorder are considered by at least some researchers to be related to one another, or to form a spectrum of conditions from mild or imperceptible to severe. The mildest types are the tics or “habit spasms” of children. These tics are usually considered psychogenic in origin because they occur more often under conditions of stress or tension. Tics of this kind are more common in boys than in girls. Common types of childhood tics include eye blinks or other facial movements, as well as occasional vocal tics such as throat-clearing noises. In some children—perhaps many—tics of this kind may disappear (or be “outgrown”) spontaneously if no attention is drawn to them.

Chronic tics can be of either the motor or the vocal type. Chronic motor tics are uncommon tics in which three or more muscle groups are usually involved at the same time. Chronic vocal tics are also uncommon and consist of uncontrolled sounds that are more often animal sounds than words of articulate speech. Either kind of chronic tic can originate either in children or in adults, even beyond the age of forty. In either case, they usually last for the remainder of the patient’s life. The disorder is equally prevalent in both sexes. Some researchers think that these chronic tics, and possibly also the transient habit spasms of childhood, may result from the same (as yet unidentified) cause as Tourette’s syndrome, but in much milder form.

Tourette’s syndrome is a neurological disorder characterized by bizarre or unusual tics, compulsive swearing or cursing, strange facial gestures, and sudden barking or other animal-like sounds. The spectrum of these tics and other symptoms is broad, which has complicated earlier attempts to describe the disease or to find its cause. The disease usually first appears in children between five and ten years of age and continues throughout life.

The variability of symptoms is one of the characteristic features or highlights of Tourette’s syndrome. According to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders: DSM-IV-TR (4th ed., 2000), among the diagnostic criteria for Tourette’s syndrome are that both motor and vocal tics must occur and that the number, frequency, complexity, severity, and anatomical location of these tics must change over time. The tics must occur many times a day, usually in bouts, and they must recur “nearly every day or intermittently throughout a period of more than one year.” The disease must appear before the age of twenty-one to be considered Tourette’s syndrome (although in many cases symptoms are so mild as to escape attention).

Associated with Tourette’s syndrome are a number of other conditions, including obsessive-compulsive behaviors,
attention-deficit disorder, hyperactivity, school phobias, test anxiety, conduct disorders, depression, dyslexia, poor socialization skills, and low self-esteem, though many of these symptoms can also appear by themselves. Several experts consider Tourette’s syndrome and attention-deficit disorder to be variable manifestations of a common underlying disorder that may relate to a chemical imbalance in the brain. About half of Tourette’s patients also show symptoms of attention-deficit disorder, such as frequent inattention, impulsiveness, and hyperactivity.

The association between Tourette’s syndrome and attention-deficit disorder should be regarded as provisional. The two disorders may have an underlying cause in common, such as a common genetic basis. In many cases, however, the motor and vocal tics are made worse by the administration of stimulants such as methylphenidate, which is commonly used for the treatment of the hyperactivity that so often accompanies attention-deficit disorder. Thus it is possible that the presence of Tourette’s syndrome in such cases may be attributable not to the attention-deficit disorder, but to the drugs used to treat the disorder. In certain cases, these drugs may have caused a transient or chronic tic disorder to progress to the more severe Tourette’s syndrome. Clearly, more research is needed to clarify the exact nature of the relationship between Tourette’s syndrome and attention-deficit disorder, both in the presence and in the absence of various drugs.

There are several other aspects of Tourette’s syndrome that are being examined. For example, a number of researchers now suspect that the factors that predispose a patient to develop Tourette’s syndrome may also predispose male patients to one form of alcoholism. Other researchers believe that the brain disorder responsible for Tourette’s syndrome is related to the endorphins, the brain’s natural opiates.

Some promising research involves the connection between this disorder and the neurotransmitter dopamine. Neurologists suspect that Tourette’s syndrome results from increased sensitivity of certain parts of the brain to dopamine. Some of the evidence for the hypersensitivity of dopamine receptors derives from the observation that drugs such as haloperidol, which is known to inhibit the dopamine receptors, are effective in reducing the symptoms of Tourette’s syndrome, while amphetamines and other drugs that enhance dopamine neurotransmission make the symptoms worse. Also, the cerebrospinal fluid of patients with Tourette’s syndrome contains reduced levels of homovanillic acid, a breakdown product of dopamine. The corpus striatum in the brain is considered to be the most likely location for the supersensitive dopamine receptors. One researcher has found a total absence of a brain peptide called dynorphin in fibers of the corpus striatum, where this peptide normally occurs. The fibers in question project to the globus pallidus at the base of the
cerebral hemispheres.

One theory that attempts to explain the relationship of the several symptoms in Tourette’s syndrome is that they all stem from a loss of the inhibition that normally controls involuntary movements. The obscene or offensive words, normally inhibited, are expressed more often than other types of words because the inhibition has been removed. This theory supposes that children who find that they have expressed “bad” words that should not have been said out loud become obsessed with these words and thus (in the absence of inhibitions) say them more often, making the problem worse.

Studies of the families of Tourette’s syndrome patients show that there are familial inheritance patterns, with many family members having at least some symptoms of tic disorders, attention-deficit disorders, or both. In many or most cases, the tic disorders of affected family members are so mild that they never caused any problems and were never mentioned to any physician. This finding leads many researchers to conclude that the underlying disorder is variable in the extent of its expression and that it is much more common than medical records show. One expert has even estimated that nearly 1 percent of the population has some form of tic disorder.

If all forms of tic disorder are included, it becomes clear that tics run in families and that Tourette’s syndrome is simply one end of a spectrum of variable expression. Studies on identical twins confirm that the trait has a genetic basis. Additional studies of family histories suggest that everyone with the gene experiences symptoms of the disorder. The penetrance of the gene is somewhat greater in males than in females, meaning that more males have symptoms while females are more often symptom-free. Among those family members who have symptoms, the expression of those symptoms is highly variable.

Mimicking some of the symptoms of Tourette’s syndrome are the so-called tardive tics that appear during adolescence or adult life. Tardive tics are considered by many researchers to be iatrogenic (drug-induced), arising from the prolonged use of neuroleptic drugs (tranquilizers) such as phenothiazines (Thorazine, Compazine, and Mellaril). Symptoms include isolated, short, quick, uncoordinated jerking movements. The mechanism by which tardive tics appear is unclear, but the same dopamine pathways may be involved as in genuine cases of Tourette’s syndrome.

Treatment and Therapy

Various treatments are available for tic douloureux, both medical and surgical. Partial relief may be afforded by medical treatments, which include carbamazepine (tegretol), trichloroethylene, anticonvulsants such as phenytoin or phenylhydatoin (Dilantin), vasodilators such as tolazoline (Priscoline), analgesic (pain-killing) drugs, vitamin B12, or the repeated injection of 95 percent ethyl alcohol directly into the trigeminal nerve ganglion.

None of these treatments is successful in all cases, however, and some, such as trichloroethylene, have toxic side effects. Surgical treatments include neurotomy (cutting of the affected branch of the trigeminal nerve), decompression of the posterior nerve root, or the cutting of one or more of the trigeminal tracts in the brain stem, either in the midbrain or in the medulla. The most frequently performed surgical procedures include destruction, or partial destruction, of the trigeminal ganglion, either by electrocoagulation, by radio frequency therapy, or by mechanical means. The facial paralysis or partial paralysis that follows nerve destruction often resembles Bell’s palsy except that the damage is usually permanent, with minimal possibility of recovery.

Treatment of childhood transient tic disorders usually consists of psychological intervention to control or reduce the level of stress. Many cases of transient or chronic tic disorder are so mild that they do not require any treatment.

For Tourette’s syndrome, haloperidol (Haldol) is most often prescribed, and it is said to be effective in 50 to 90 percent of the cases, depending on the authority consulted. Other drugs occasionally prescribed include clonidine, penfluridol, and pimozide. These drugs can reduce the severity and frequency of tics and may reduce impulsive or aggressive behavior. They also have side effects, however, causing sedation, depression, and weight gain in many patients.

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