Tourette Syndrome and Tic Disorders in Children and Adolescents

Robert A. King

Tamar Steinberg

Tics are sudden, involuntary, repetitive, but nonrhythmical movements or vocalizations. They range in number, frequency, persistence, and associated comorbidity from the isolated transient symptoms found in transient tic disorder to the chronic, multiple motor and vocal tics of Tourette syndrome (TS) that are often accompanied by various forms of psychopathology (see Definitions and Natural History and Clinical Phenomenology, further on).

TS stands as a model developmental neuropsychiatric disorder in several respects (1). Although clearly neurological in origin (with a complex genetic and neurobiological substrate), the clinical phenomenology and course of the disorder are influenced by the interplay between genetic and environmental protective and risk factors (including perinatal adversity and hormonal exposure, infection, and psychological factors such as stress). Over and above the direct psychosocial burden that significant tics pose for the child and family, TS is associated in many cases with increased autonomic lability, vulnerability to anxiety and/or depression, and a spectrum of attentional and neurocognitive difficulties (2). Thus, a comprehensive approach to understanding and treating the tic disorders requires an appreciation of multiple explanatory frames of reference (genetics, neurobiology, immunology) and clinical modalities (pharmacological, cognitive behavioral, psychodynamic, family, neuropsychological, educational). Not surprisingly, then, children with tic disorders are often seen by both pediatric neurologists and child psychiatrists, as their comprehensive evaluation and management requires a broad biopsychosocial approach.

Estimates of the prevalence of tics vary widely depending on age (prevalence decreases with age), methods of ascertainment (parental report, direct observation, clinical records), and definition. [In contrast to earlier versions of the DSM, DSM-IV-TR (3) dropped impairment as a diagnostic criterion for TS.]

Transient tics are common in school-aged children, with estimated prevalences ranging from 4% to 24% (4, 5, 6). For example, direct classroom observation on multiple occasions of community school-aged children found that 18% of 5- to 12-year-olds had a single tic or transient tics, whereas an additional 6% had multiple or persistent tics (5). Prevalence estimates for school-aged children with TS also vary widely, from about 5 to 100 per 10,000, with community samples showing substantial higher rates than clinical samples, suggesting that many cases remain undiagnosed or untreated (4,7). Boys are more likely than girls to manifest tics, with a gender ratio of about 2:1. TS has been described in most ethnic groups studied, with differences in reported rates in clinical settings most likely
reflecting propensity to seek help, rather than true ethnic variations in prevalence. In a community epidemiologic survey, the Great Smoky Mountains Youth Study found no differences in prevalence rates for tic disorder or TS between white and African-American children or across income groups (4).

Definitions

MOTOR TICS

Simple motor tics are sudden, fleeting, or fragmentary movements such as blinking, grimacing, head jerking, or shoulder shrugs. Complex motor tics consist of several simple motor tics occurring in an orchestrated sequence or semipurposeful movements, such as touch or tapping; these may also have a more sustained, twisting, dystonic character.

PHONIC TICS

Simple phonic tics consist of simple, unarticulated sounds such as throat clearing, sniffing, grunting, squeaking, or coughing. Complex phonic tics consist of out-of-context syllables, words, phrases, or paroxysmal changes of prosody.

Complex tics may involve socially inappropriate or obscene gestures (copropraxia) or utterances (coprolalia), as well as echo phenomena, such as echolalia or echopraxia (repeating others’ words or gestures), which exemplify the suggestibility of tics. Infrequently, complex tics may include self-injurious behavior (cheek chewing, eye poking, self-hitting).

Diagnostic Criteria

The following diagnostic criteria are from reference 3.

DSM-IV-TR diagnostic criteria for transient tic disorder

A. Single or multiple motor and/or vocal tics (i.e., sudden, rapid, recurrent, nonrhythmical, stereotyped motor movements or vocalizations).

B. The tics occur many times a day, nearly every day for at least 4 weeks, but for no longer than 12 consecutive months.

C. The onset is before age 18 years.

D. The disturbance is not due to the direct physiological effects of a substance (e.g., stimulants) or a general medical condition (e.g., Huntington disease or postviral encephalitis).

E. Criteria have never been met for TS or chronic motor or vocal tic disorder.

Diagnostic criteria for chronic motor or vocal tic disorder

A. Single or multiple motor or vocal tics (i.e., sudden, rapid, recurrent, nonrhythmical, stereotyped motor movements or vocalizations), but not both, have been present at some time during the illness.

B. The tics occur many times a day, nearly every day or intermittently throughout a period of more than 1 year, and during this period there was never a tic-free period of more than 3 consecutive months.

C. Criteria C, D same as above.

E. Criteria have never been met for TS.

Diagnostic criteria for Tourette syndrome

A. Both multiple motor and one or more vocal tics have been present at some time during the illness, although not necessarily concurrently.

B. The tics occur many times a day (usually in bouts) nearly every day or intermittently throughout a period of more than a year, and during this period there was never a tic-free period of more than 3 consecutive months.

C. Criteria C, D same as above.

It is not clear to what extent these DSM frequency and duration criteria truly demarcate distinctive syndromes with differing etiologies, symptomatic concomitants, or clinical courses, rather than points on a spectrum of symptomatic severity in the expression of a common underlying genetic vulnerability.

Natural History and Clinical Phenomenology

The most common age of onset for tics is between 4 and 6 years of age. Initial sniffing or blinking tics may be mistaken for allergies or eye problems. It is only with their waxing and waning and the subsequent appearance of other tics that the diagnosis becomes clear. There is also often an anatomic progression, with head and facial tics being the first to appear and more caudal and more complex tics appearing later.

Stress (8), fatigue, exciting events (trips, beginning of school), or even childhood colds (9) can exacerbate tics. Tics are often transiently suppressible, which may lead adults to draw the mistaken conclusion that they are voluntary, because they may appear in one setting but not another. Tics may also diminish or disappear during tasks that require focused attention and fine motor control, such as music or sports. They often diminish or disappear during sleep but can recur during rapid eye movement (REM) and other sleep phases. The characteristic pattern is for tics to wax and wane in bouts over the course of the day and weeks, with the disappearance of one tic to be replaced by different ones.

By middle childhood, many youngsters with chronic tics are able to describe and localize premonitory sensations or urges that precede the tics (10). These sensations or urges may be described as an “itch” or “tickle” that is transiently relieved by performing the tic and that grows worse if the tic is suppressed or resisted. In this sense, many children report, in essence, that their tics straddle the boundary between “voluntary” and “involuntary,” “physical” and “mental.” For some children, the constant bombardment of premonitory urges may be as distracting or debilitating as the tics themselves.

Once considered a disabling and lifelong disorder, it is now clear that most cases of TS are mild, with marked improvement or remission of tics in the majority of cases by late adolescence (6,11,12). The period of “worst-ever” tic severity usually spans 7 to 12 years of age, following which tics often improve spontaneously in terms of frequency and subjective distress. By later adolescence or young adulthood, three quarters of childhood cases, tics disappear or decrease substantially, 15% remain stable, and 15% worsen (11,13). [Video and direct observation may reveal more residual tics than does self-report (14).] Unfortunately, comorbid symptoms of attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and anxiety may not show the same improvement with age (12). Indeed, the presence of comorbid OCD, phobias, or ADHD in childhood or early adolescence may be predictors of more persistent tics (6).

COMMON COMORBID DISORDERS

In addition to the pathognomonic tics of TS, many patients also suffer from symptoms of OCD, ADHD, impulsivity, proneness to anxiety and depression, uneven neuropsychological profiles, and learning difficulties (2). When present, these comorbid conditions may be more distressing or impairing than the tics themselves, and hence are important targets of assessment and intervention. Youngsters with TS plus comorbid OCD and/or ADHD usually have more adaptive difficulties than those with tics alone (15,16). Sleep problems and migraine may also be more common in individuals with TS. Trichotillomania or body dysmorphic disorder may also be more common in probands with TS and their relatives.

Obsessive-compulsive disorder

The prevalence of obsessive-compulsive symptoms ranges from 11% to 80% in clinical and community samples, depending on the sample, means of assessment, and criteria used (2). Viewed in isolation, simple compulsions may be difficult to distinguish from complex tics (e.g., forced repetitive touching, which may include dangerously hot objects). (Some patients differentiate tics prompted or accompanied by a physical sensation from compulsions prompted by mental phenomena.) Although patients with TS may manifest the usual harm-avoidant obsessions and compulsions found in OCD patients without tics, concerns about symmetry, ordering, and exactness, as well as intrusive aggressive, sexual, or religious images, appear to be more common in tic-related OCD. TS-related compulsions are often driven by the need to get some appearance or physical sensation “just right,” rather than by anxiety reduction or harm avoidance. (For example, a youngster may need to set down a cup repeatedly until he or she feels or hears the right “clunk”; repeat an action in odd- or even-numbered sets; or go through a doorway precisely through the middle or by leading with the right foot.)

Attention deficit hyperactivity disorder

ADHD, as well as oppositional behavior, is found in at least one half of clinically referred children and adolescents, with considerably lower rates in nonreferred samples (6), suggesting that comorbid ADHD may be an important predisposing factor for seeking clinical help. It is also not uncommon to see children with ADHD who have developed transient or persistent tics after being started on stimulant medication, posing a sometimes difficult therapeutic dilemma (see Treatment of Comorbid Attention Deficit Hyperactivity Disorder, further on.)

Differential Diagnosis of Tic Disorder

The diagnosis of tic disorder for TS is straightforward in most cases. Tics can usually be distinguished from other movement disorders in that they are semivoluntary (partially suppressible), often preceded by an urge or premonitory sensation, and reproducible on request; they occur in repetitive patterns (over the short run) and may persist, albeit diminished, in sleep (17). To make the diagnosis, a detailed history, with special attention to these features, and a thorough physical examination are necessary. When conducting a physical examination, it should be taken into consideration that a patient may have a mixture of movement disorders. For example, a patient treated with neuroleptics may suffer from tics, akathisia, tardive or withdrawal dyskinesia, and/or drug-induced acute dystonia simultaneously (18). (Some children have both tic disorder and motor stereotypies.) Children
with uncomplicated tic disorder have a normal neurological examination, although formal neuropsychological testing may reveal subtle difficulties in fine visuomotor coordination (19).

In most typical cases, the diagnosis can be made without electroencephalogram (EEG), magnetic resonance imaging (MRI), or laboratory studies, such as serum copper or ceruloplasmin.

STEREOTYPICAL MOVEMENTS

Distinguishing true tics from stereotypies or self-stimulating behaviors, such as rocking, head banging, flapping, or spinning, is a common diagnostic problem in young children. Compared with tics, stereotypies usually have an earlier onset (often by age 3 years), greater complexity, and relatively fixed form and locus, and they appear more voluntary in nature. When old enough, children usually describe their tics as intrusive, bothersome, disruptive, and largely involuntary. In contrast, stereotypies are often bothersome to parents, but not to the child who often appears to find them pleasurable and resists adult attempts to interrupt them. These apparently self-stimulating movements occur largely at times of boredom, excitement, or, less commonly, distress but rarely disrupt coordinated movements and usually persist over months and years without much change in form or location. Although common in children with pervasive developmental disorders (20), they can also be seen in developmentally normal children with normal intelligence quotients (IQs) (21) and may run in families.

CHOREA

Chorea is a syndrome characterized by a continuous flow of abrupt, involuntary muscle contractions producing irregular, unpredictable, brief, jerky movements that migrate randomly from one part of the body to another. Unlike tics, choreic movements are not preceded by an urge or premonitory sensations.

Postinfectious forms of chorea

The commonest cause of childhood chorea is Sydenham chorea (SC), presumably an autoimmune poststreptococcal disorder associated with rheumatic fever (see Chapter 3) (22). The typical age at onset of SC is 8 to 9 years and is very rarely seen in children younger than age 5 years. Typically, children develop the disease 4 to 8 weeks after streptococcal pharyngitis, but longer intervals may occur. As noted in the section on pediatric autoimmune neuropsychiatric disorders associated with streptococcus (PANDAS), children with SC commonly display other de novo neuropsychiatric symptoms, such as tics, attentional disorders, and OCD. SC is usually a self-limiting disorder lasting 8 to 9 months, but up to 50% of children may show persistent chorea at 2-year follow-up. Other infections may also cause chorea (see Chapter 3).

In contrast to children with SC, those with tic disorder or OCD hypothesized to be due to PANDAS by definition do not have a history of full-blown chorea but may show fine “choreiform” movements, pronator drift, or motor impersistence in stressed postures. Children with putative PANDAS have also been found to have normal echocardiograms.

Drug-induced chorea

Various drugs, including antiepileptic drugs, psychostimulants, dopamine receptor blocking agents, and oral contraceptives, can also induce chorea.

Genetic forms of chorea

Benign hereditary chorea, ataxia telangiectasia, paroxysmal kinesogenic choreoathetosis, Wilson disease, and Huntington disease (HD) can all cause movement disorders with choreiform movements. Although chorea is the prototypical movement disorder in HD, patients can also present with eye movement abnormalities, dystonia, myoclonus, ataxia, dysarthria, dysphagia, or tics (23). In early-onset cases of HD in children and adolescents, parkinsonism or dystonia, rather than chorea, may predominate (see Chapter 3).

MYOCLONUS AND SEIZURES

Myoclonic jerks

Myoclonic jerks are brief (<200 ms) shocklike muscular contractions that lack the continuous random flow of movements typical of chorea and, unlike tics, are completely involuntary. Myoclonic jerks of the shoulders and arms appearing shortly after awakening are typical of juvenile myoclonic epilepsy (JME); the large majority of these patients also experience grand mal or absence seizures. Segmental spinal myoclonus may be associated with several spinal cord disorders, including various forms of progressive ataxia.

Epilepsies with typical absence (petit mal)

Absence seizures are characterized by a brief lapse of consciousness lasting 5 to 10 seconds. With hyperventilation or photic stimulation, the EEG study demonstrates 3-Hz spike and wave discharges (24). Minor movements occur in 70% of patients during episodes, including lip smacking or twitching of the eyelids or face; transient slight loss of body tone can cause the child to drop objects. Some absence attacks are more complex, with behavioral automatisms or prolonged symmetric myoclonic movements of the head or extremities. In contrast to the brief lapses of consciousness found in absence seizures, individuals with tics remain fully conscious during their movements.

Epilepsies with complex partial seizures, temporal lobe seizures

These seizures arise from a focal origin, most commonly in the temporal lobe, and produce a period of impaired consciousness accompanied by staring or a dazed expression, oral movements or drooling, muttering or mumbling, stiffening of body or limbs, searching or orienting movement, or other behavioral changes. In general, the younger the patient, the less complex is the seizure. Typically, younger children have automatisms characterized by lip smacking, chewing, or other automatisms. Some patients can describe an aura preceding the seizure, which consists of visceral sensations and anxiety (25). In contrast to complex partial seizures, tics are usually at least transiently suppressible and are not accompanied by an alteration in consciousness, postictal confusion or tiredness, or amnesia for the event.

DYSTONIA

Dystonia is characterized by sustained muscle contractions causing repetitive twisting movements or abnormal postures caused by simultaneous contraction of agonist and antagonist muscles (26). Dystonia can be either primary or secondary to another disorder. Examples include cervical dystonia, which causes the head to turn in a consistent direction, or blepharospasm, which produces involuntary closure of the eyes. The movements
are prolonged and patterned, and they involve the same muscle group over time, in contrast to the usual pattern of multiple fluctuating tics found in TS. Unlike tics, dystonic movements are not preceded by an urge, and there is no relief when the movement is executed. Many patients discover a tactile or proprioceptive sensory trick that reduces the dystonia. For instance, patients with cervical dystonia may be able to keep their head upright by touching their chin.

Dystonia is aggravated by voluntary movements. Task-specific dystonia occurs only during a specific action such as writing (writer’s cramps). Dystonia is worsened by fatigue and stress and abates with relaxation or sleep. Dystonia can be focal, most commonly involving the neck, oromandibular, or periorbital muscles. It can also be segmental, multifocal hemidystonia or generalized.

Early-onset dystonia appears around age 9 years, is characterized by involvement of limbs, and rarely involves the neck or cranial nerves. About 50% of early-onset dystonias become generalized and, compared with adult-onset cases, are more often primary.

Commercial clinical screening is available for the commonest genetic form of primary dystonia, a deletion in the DYT1 gene located on chromosome 9q34.21.

NEUROACANTHOCYTOSIS

The term neuroacanthocytosis is used to describe a group of rare disorders associated with neurological symptoms and acanthocytes, erythrocytes with an unusual starlike appearance with spiky- or thorny-appearing projections that can be seen on blood smear.

One such disorder that causes chorea and tics is Levine-Critchley syndrome, produced by a mutation in a specific gene called chorein (also called VPS13A). In contrast to TS, the onset of the disorder, usually in the third or fourth decade of life, is first manifested by lip and tongue biting, which is followed by orolingual dystonia, chorea, and motor and vocal tics, as well as personality changes, cognitive decline, seizures, dysphagia, and dysarthria. Specific genes have also been identified for several other genetic syndromes involving movement disorder with choreiform or Parkinson-like features, various other neurological abnormalities, and acanthocytosis (27). Laboratory findings include more than 3% acanthocytes on the peripheral blood smear and elevated creatine phosphokinase (CPK) as a result of muscle wasting (28). Brain MRI demonstrates caudate atrophy and increased signal in caudate and lentiform nuclei.

TARDIVE DYSKINESIAS

Tardive dyskinesias (TDs) are involuntary movements of the tongue, lips, face, trunk, and extremities that occur in patients treated with long-term dopamine antagonist medications. This disorder is quite rare in children and is much more commonly found in elderly patients with prolonged neuroleptic use. Although most often associated with the use of the typical neuroleptics, tardive dyskinesias may occur from other types of exposure; individuals with schizophrenia appear especially vulnerable to developing TDs after exposure to anticholinergics, substances of abuse, toxins, and other agents.

The dopamine-receptor antagonists that are frequently used to treat patients with tics may themselves cause movement disorders, including “tardive tourettism” (29), a form of tardive dyskinesia that includes motor and vocal tics. The diagnosis of acute and chronic dyskinesia is based on precise medical and pharmacological history documentation. TDs may improve with increased doses of dopamine antagonists, making the differential diagnosis more complex. This disorder, as opposed to TS, is much more common in elderly patients with prolonged neuroleptic use and is quite rare in children.

CONVERSION DISORDER

Adolescents with dramatic whole-limb movements, unusual gait, shaking, or other dramatic movements may sometimes be misdiagnosed as having a tic disorder, rather than receiving the correct diagnosis of conversion disorder. Unlike tic disorder, conversion disorder often does not appear until adolescence, usually without any convincing history of significant earlier simple motor or phonic tics. (It is very rare to have significant complex tics without a history of simple tics.) Save in cases of well-established tic disorder in which prolonged bouts may sometimes be seen, most bouts of tics are fleeting; in contrast, conversion disorder movements may continue uninterrupted for minutes. Youngsters with flurries of dramatic true tics are usually quite distressed by them, in contrast to those with conversion disorder, who may appear relatively unconcerned at the degree of seeming functional impairment. Finally, a family history of tics or OCD is common in tic disorder but may be absent in conversion disorder.

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