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Movement Disorders I: Tics and Stereotypies

2010; American Academy of Pediatrics; Volume: 31; Issue: 6 Linguagem: Inglês

10.1542/pir.31.6.223

1529-7233

Samuel H. Zinner, Jonathan W. Mink,

Genetic Neurodegenerative Diseases

After completing this article, readers should be able to: Movement disorders involve impairment of appropriate targeting and velocity of voluntary movements, dysfunction of posture, the presence of abnormal involuntary movements, or the performance of normal-appearing movements at inappropriate or unintended times. The abnormalities of movement are not due to weakness or abnormal muscle tone but may be accompanied by weakness or abnormal tone. By convention, movement disorders are divided into two major categories. The first category is hyperkinetic movement disorders, sometimes referred to as dyskinesias. This term refers to abnormal, repetitive involuntary movements and includes most of the childhood movement disorders, including tics, stereotypies, chorea, dystonia, myoclonus, and tremor. The second category is hypokinetic movement disorders, sometimes referred to as akinetic/rigid disorders. The primary movement disorder in this category is parkinsonism, manifesting primarily in adulthood as Parkinson disease or one of many forms of secondary parkinsonism. Hypokinetic disorders are relatively uncommon in children. Although ataxia, weakness, and spasticity are characterized by motor dysfunction, by common convention these entities are not included among "movement disorders."This review of movement disorders consists of two parts. Part I focuses on the most common movement disorders of childhood: tics and stereotypies. Part II examines chorea, dystonia, myoclonus, tremor, and drug-induced movement disorders.Most movement disorders in childhood arise from dysfunction in basal ganglia (caudate, putamen, globus pallidus, subthalamic nucleus, substantia nigra) and frontal cortex. However, the accomplishment of normal movement requires a multifaceted network of brain regions, including basal ganglia, frontal cortex, parietal cortex, thalamus, cerebellum, spinal cord, peripheral nerve, and muscle. Recognition of the multiple components of the nervous system involved in motor control is important because the etiologic diagnosis often depends on localization.When faced with a movement disorder, the first step is to characterize the movement. Is the pattern of movements normal or abnormal? Are there excessive movements or is there a paucity of movement? Is the movement paroxysmal (sudden onset and "offset"), continual (repeated again and again), or continuous (without stop)? Has the movement disorder changed over time? Do environmental stimuli or emotional states modulate the movement disorder? Can the movements be suppressed voluntarily? Is the abnormal movement heralded by a premonitory sensation or urge? Are there findings on the examination suggestive of focal neurologic deficit or systemic disease? Is there a family history of asimilar or related condition? Does the movement disorder abate with sleep?In clinical practice, the diagnosis of a movement disorder requires a qualitative appreciation of the movement type and context. Classification of the disorder phenomenologically requires a description of the characteristics of the movements (Table 1). Even under the best circumstances, abnormal movements can be difficult to define, and movement disorders may be difficult to characterize. Chorea can resemble myoclonus. Dystonia can resemble spasticity. Paroxysmal movement disorders such as dystonia and tics may resemble other paroxysmal neurologic problems, namely seizures. Movements in some contexts may be normal and in others may indicate underlying disease. Movements that suggest a degenerative disorder in adolescents (myoclonus) may be completely normal in an infant (benign neonatal myoclonus). It can be difficult to diagnose a specific movement disorder without seeing the abnormal movements. Thus, obtaining video examples of the child's movement may be essential to making a correct diagnosis.Tic disorders, including Tourette syndrome (TS), are among the most common of neurologic conditions. Surprisingly, however, they escaped significant scientific attention until recent decades, in part due to their protean and evolving qualities. Although tic disorders, including TS, no longer are considered rare, misconceptions persist, rooted in obsolete theories. For example, during the era of the late 1800s, when Georges Gilles de la Tourette first described the condition that later would bear his name, "hysteria" and "neurosis" were the prevailing interpretations regarding cause; later interpretations suggested tics to be representations of narcissism.The etiologic model shifted suddenly toward a neurologic explanation in the early 1960s after neuroleptic medication was discovered to diminish tic production in patients who had TS. At that time, although tics themselves were viewed as common among school-age children, TS was viewed distinctively and grimly. Medical journals of the era described TS in such terms as "monstrous affliction," offering prognostic statements that described a uniformly poor outcome, often culminating in personality deterioration or foreshadowing insanity, schizophrenic psychosis, and certain commitment to mental hospitals. So stigmatizing was the disorder that one author recommended avoiding use of the Tourette eponym because its pleasant sound was considered too incongruous with the presumed grave outcome. Experts of the era considered TS to be extremely rare, suggesting that many physicians would never see a case. In a 1966 report, the Mayo Clinic had made the diagnosis in just 7 of 1.5 million newly admitted patients over the preceding 3 decades; another review reported only 4 cases among 59,000 admissions to a psychiatric clinic.Today, TS and related disorders are viewed as common, although the neurobiologic underpinnings remain poorly understood. It generally is agreed that TS has a genetic basis and that tics arise from basal ganglia-thalamocortical circuits. However, the specific causative mechanisms are not known.Tics are nonrhythmic, repetitive, and intermittent muscle contractions resulting in "stereotyped" (ie, performed identically each time) movements. When these movements involve laryngeal-pharyngeal muscles and produce noise, tics are termed "phonic" or "vocal." All other tics are termed "motor," although functionally, phonic tics also are motoric. (For a video of a patient who has Tourette syndrome demonstrating facial and vocal tics, see the Data Supplement.)Both motor and phonic tics can be characterized further as "simple" or "complex" (Table 2). Simple tics tend to appear meaningless, be anatomically isolated, or be of brief duration but are excessive in frequency or intensity. Complex tics may mimic a gestural or linguistic purpose, involve several muscle groups, or be more sustained, such as the holding of a posture. Other features of complex tics can include socially unacceptable expressions, such as coprolalia (utterance of foul or other inappropriate language) and copropraxia (making offensive gestures), or a self-injuring action. The range of possible tic manifestations is virtually infinite, however, obscuring clear boundaries between simple and complex classifications.The Diagnostic and Statistical Manual of Mental Disorders, 4th edition-Text Revision (DSM-IV-TR), published in 2000, classifies tic disorders as "transient" (lasting between 1 and 12 months) or chronic (lasting more than 12 months). Chronic tic disorders are classified further either as "chronic motor or vocal tic disorder" or as "Tourette's disorder," the latter requiring the presence of both motor and phonic tics. Note that the term "vocal" implies a laryngeal contribution, although some noise-producing tics involve only naso- or oropharyngeal muscles, such as sniffing or tongue clicking, so the term "phonic" may be more precise. Additional criteria for all tic disorders include tic onset prior to 18 years of age and the presence of tics nearly daily or intermittently during the qualifying period of time.A departure from the original DSM-IV, published in 1994, is the removal of the criterion that the disturbance must cause marked distress or significant impairment in social, occupational, or other important areas of functioning. This distinction is noteworthy because the absence of this criterion further supports the neurologic basis of tic disorders. When the presentation does not completely fulfill the criteria in any of the three classifications, a fourth classification, "tic disorder – not otherwise specified," can be chosen.Tic disorders begin in childhood, usually emerging during the first decade. Transient motor tics occur in as many as one in four children and may represent a normal variant of childhood neurodevelopment. Because tics ordinarily are mild in severity and because of their commonness, they often are overlooked entirely. The prevalence of TS today is recognized to be about 1%, a dramatic increase from even very recent estimates. Boys are four times as likely as girls to have TS.Most individuals who have chronic tic disorders experience only mild and unambiguous tics, with simple motor tics, such as eye blinking, by far the most common and earliest manifestation. Complex tics are less common and are very unlikely to occur as the first tic, if at all. However, among people who have chronic tic disorders, tics often become more complex over time. Among those who have non-TS chronic tic disorders, phonic tics are much less common than motor tics. When present, phonic tics are much more likely to be of the simple, rather than complex, variety. Very few people who have TS ever develop coprolalia, despite the disproportionate media portrayals of this often startling feature and earlier investigators' expectations of a dismal unfolding of symptoms. When chronic, tic severity usually peaks in the preadolescent years, and most affected adolescents experience significant improvement or complete resolution into adulthood.The pathogenesis of tic disorders is complicated and not well understood, although a wealth of biomedical research strongly supports a defective filtering, or "sensorimotor gating," mechanism, resulting in urges to perform elements of otherwise purposeful activity at inappropriate times, intensities, or frequencies. The central concept focuses on the basal ganglia and their role within brain-based circuits that also include the neocortex and thalamus. Other key brain regions, such as the midbrain, may be involved as well. When functioning properly, the basal ganglia assist in the execution of desired behaviors expressed by these circuits, but the basal ganglia also function to prevent the completion of undesired behaviors.Many desired behaviors, when learned through repetition, may become automatic or sequenced as "prepackaged and ready-to-use," perhaps stored and reinforced in these circuits. Imprecise regulation results in the expression of bits of these behaviors, such as tics. This model also helps to explain related or comorbid conditions that, like tics, share features of loss of behavioral inhibition, such as compulsions or impulsive behaviors, and to explain why these behaviors often mimic purposeful activities.Chronic primary tic disorders and many of their associated conditions are strongly influenced genetically, although the inheritance pattern is unclear. Environmental factors, such as sleep insufficiency, stress, and possibly in utero exposure to maternal smoking, also are important as mediators of symptom severity. In 2005, the first reported gene associated with TS was identified on chromosome 13 in 3 of 174 patients, although subsequent studies of this gene's association with TS have yielded mixed findings. In 2007, strong linkage to chromosome 2p was reported in a large genome scan. It is likely that the genetics of TS are more complex than previously believed. An autosomal dominant mode of transmission with incomplete penetrance and possible polygenic and additive factors and environmental influences seems likely.Transient tic disorders may be milder than chronic conditions and are less likely to be associated with other developmental and behavioral conditions. However, it is important to note that diagnostic criteria make no mention of tic severity. Tics in TS may be mild and unrecognized by casual observers. When tics are chronic, they typically change in anatomic location, frequency, type, complexity, and severity or interference. New tics may replace older ones or add to a growing repertoire. Other important features of tic disorders include a waxing and waning course, often observed as bouts of tics over periods of seconds, minutes, hours, days, weeks, months, or longer.Chronic tic disorders frequently are associated with one or more comorbid conditions (Table 3), and it is these conditions, rather than the tics themselves, that most often are the source of the greatest psychosocial and functional challenges. Children who have TS but no comorbid conditions probably have a similar quality of life and function as children who have no TS. As described earlier, the feature of behavioral disinhibition in tics is shared with some aspects of attention-deficit/hyperactivity disorder (ADHD) as well as obsessive-compulsive disorder (OCD) and obsessive-compulsive behaviors and may suggest common neurologic underpinnings. In fact, ADHD occurs in at least 50% of clinically referred children who have TS, and OCD occurs in about 33%. Symptoms of ADHD usually precede the onset of tics in most individuals, often presenting during the toddler and preschool years.Learning disabilities (LDs) are another common co-occurring problem, although children who have TS may face obstacles to effective learning due to reasons other than LD, including ADHD, obsessive thoughts or compulsions, and complications due to other comorbid conditions, such as anxiety, poor frustration tolerance, insufficient sleep, and executive function difficulties such as poor organizational skills. Tics themselves can interfere with operations such as reading, writing, listening, and speaking. In addition, tics can be distracting and sometimes physically challenging, further jeopardizing the child's ability to attend.Explosive anger and aggression, or episodic "rage attacks," are seen in 25% or more of referred patients who have TS, and parents overwhelmingly regard these events as the most problematic feature. Their origin likely is multifactorial, related both to primary disorders and secondary consequences of having a chronic disorder. These attacks may be related to comorbid conditions, including aggressive obsessions or other anxieties, loss of impulse control or other disinhibited urges, and hyperarousal.Although tics often improve or resolve in adolescence and young adulthood, it is not yet possible to predict a tic course for individual patients. A growing identification of endophenotypes, such as fine motor skills deficits, is emerging that may suggest degrees of basal ganglia dysfunction that could help serve as clues to predict greater tic severity in adulthood.Diagnosing tic disorders is clinical and usually straightforward, not requiring any laboratory or imaging studies. Most often, parents or patients self-diagnose and seek confirmation from a specialist. Simple motor tics seldom pose diagnostic uncertainty; complex tics and phonic tics may be more difficult to discern. Although tics may resemble chorea or myoclonus in some cases, the presence of a premonitory sensory urge that is relieved by tics and the ability to suppress tics voluntarily distinguish tics from true involuntary movement disorders. Rarely, tics can be symptomatic of other disorders (Table 4). In those cases, there usually are other signs or symptoms to distinguish such secondary tic disorders from primary tic disorders. A comprehensive history (including family history of tics and associated problems) and physical examination can rule out most of these causes. If there is diagnostic uncertainty, referral to a neurologist is indicated.Additional screening and ongoing monitoring to assess for the presence of any of the psychosocial, behavioral, learning, and developmental comorbid conditions are essential in providing comprehensive care. When screening identifies concerns beyond the scope of general primary care diagnosis or management, specific consultation or referral for more specialized medical, psychosocial, or psychoeducational evaluations may be indicated. An evaluation by a medical specialist, such as a developmental/behavioral pediatrician, psychiatrist, or neurologist, includes an assessment of past medical, family, and developmental history; a social and environmental overview; a review of the onset and course of tics and related problems; and a complete physical examination with direct clinical observation. When screening suggests the presence of obstacles to optimal academic and social performance, psychosocial and psychoeducational assessments within the school district or the private domain are indicated.Management starts with education about tic disorders as neurologically based, which often includes reversing long-held misconceptions and myths. Solicitation of beliefs and concerns from patients and families can help guide educational approaches. For example, awareness that tics may be suppressible can mislead parents or teachers to assume that tics are deliberate. Also, attention to the tics may be misplaced or overemphasized, and when overlooked, comorbidity may be a much more significant source of functional difficulty. At the same time, comorbid challenging behaviors may be regarded as an irremediable part of the broad TS spectrum and not amenable to disciplinary guidance, an assumption that is invalid. Comorbid problems often accompany disruption in family and peer relations, and effective intervention relies first and foremost on successful, positive parenting foundations. Professional family, individual, or parenting counseling may be considered.The first approach to managing tic disorders should be providing education and reassurance. Parents, patients, educators, and peers may benefit from education about tics and TS. An understanding of how symptoms of tics and comorbid problems affect the patient, family, and others can help to prioritize and establish a sensible direction and degree of intervention. In recent years, an abundance of new educational resources on TS and related conditions has become available, owing, in part, to increased awareness and research as well as to a collaborative agreement between the Tourette Syndrome Association and the Centers for Disease Control and Prevention. Some of these materials are listed at the end of the article under "DVD Educational Programming."When tics are chronic, anticipatory guidance can help avert needless interventions. In these cases, the basis of management focuses on forming an identity separate from the tic disorder and maintaining and supplementing the development of academic, organizational, and interpersonal skills with an eye to ensuring a satisfying, independent adulthood. When tics cause impairment, specific treatment of the tics may be indicated. It is important to establish clear treatment goals, with the expected outcome being the reduction rather than the eradication of tics. For most, however, ongoing monitoring and reassuring periodic reminders that chronic tics usually improve during adolescence are adequate tic management.Children who have special educational needs should be evaluated in this area and identified needs addressed accordingly. Such needs may include complications due to tics. In 2006, the United States Department of Education, Office of Special Education Programs, formally included TS as a condition in the category of "Other Health Impairment," eligible for special education services under the Individuals with Disabilities Education Act. Additional information is available through the United States Department of Education at http://idea.ed.gov. The "Education/Education Advocacy" link on the Tourette Syndrome Association web site provides a wealth of suggestions and guidance.Comprehensive behavioral intervention for tics (CBIT) is a behavior-based strategy that has shown preliminary evidence of efficacy; additional investigation is underway. The theoretical principle behind this strategy relies on the roles that internal and external environmental influences contribute to promoting tics and assumes that tics are, in part, negatively reinforced learned behaviors. This interpretation means that tics are performed to some degree because they eliminate the negative experience of the premonitory sensory urge, thereby providing temporary relief to the TS sufferer, and the repetition of tics and their associated experiences of relief reinforce the tic behavior. Accordingly, CBIT employs an individualized "competing response training" (CRT) with "functional analysis" to disrupt the urge-tic-relief cycle that, when successful, seems ultimately to weaken the urge. The nuts and bolts of CRT involve strengthening the patient's awareness of the internal environment (ie, premonitory urge) so as to anticipate an impending tic and gradually replace it with a competing tic-incompatible behavior. The functional analysis piece identifies and modifies reinforcements in the external environment that promote tics (eg, parents inappropriately indulging a child's wish not to do homework to avoid anxiety and resultant tic exacerbation) as well as those that reduce tics (eg, appropriately praising a child for practicing CRT).A variety of psychotropic medications is available and potentially useful for the amelioration of behavioral and psychosocial symptoms due to tics and comorbid conditions. Medication management of patients who have TS usually addresses problems related to tics, ADHD, anxiety (including OCD), or a combination. Although each diagnostic condition must be considered individually ("splitting"), contributions of self-esteem, parenting practices, social milieus of family and community, learning or organizational barriers, temperament, and other elements strongly influence functional outcomes in all aspects of the patient's illness. Effective interventions rely on the identification and monitoring of these modifiable factors, a point that should be underscored and repeated.Historically, even mild tics were treated medically with "typical neuroleptics" (older-generation antipsychotics), but today a more conservative approach is recommended. Features of tic severity, including frequency, functional interference, distraction, intensity, self-injurious aspects, and social implications, help to guide decisions regarding treatment, and all approaches are individualized. No medication has been designed specifically for tic reduction, and none eliminates tics entirely. A reasonable goal is to reduce tic severity to a state of tolerable functional outcome that has acceptable adverse effects. Because tics tend to increase during times of stress, it may be useful to provide reassurance and monitoring during such periods, rather than initiating or resuming medication control. In so doing, the child or adolescent may learn to "ride the wave" and recognize that successful relief from tics can come with patience, while also helping to build attitudinal tolerance to the natural ebbs and flows of the disorder. It is important to recognize that the waxing and waning pattern persists during medication use. Therefore, changes in tic severity or expression should not be assumed to be a result of the medication.When it is decided to use medication, the most consistently effective available tic-reducing agents work by blocking dopamine neurotransmission within regions of the basal ganglia. Both typical and atypical neuroleptics are useful, although adverse effect profiles limit their selection as first-line agents. Research trials of children and adolescents investigating the safety and efficacy of medications for tic reduction have been very limited, despite a growing array of available treatments. Clinical decisions are informed largely by results from trials of adults and by prevailing practice patterns. Development of research units in pediatric psychopharmacology has helped to rectify these serious limitations, and progress is ongoing but very slow.The primary indication for treatment is the extent to which tics bother the child. Tics of mild severity do not require pharmacologic intervention. Medication may be indicated for moderate-to-severe tics, but reasonable expectations must be understood. Table 5 presents medications listed by class that are used for tic reduction. Scahill and associates have prepared more detailed guidelines (see Suggested Reading). Some therapeutic combinations can benefit both tics and comorbid complications and may help guide medication selection. For example, alpha-2-adrenergic agonists can assist in tic reduction and may aid some in reducing symptoms of ADHD and insomnia; atypical neuroleptics can be useful for tic reduction and comorbid aggression.A conservative medication approach for moderate-to-severe tics begins with an alpha-2-adrenergic agonist. Families should be informed that these drugs may require up to 2 months to achieve benefit. The neuroleptic agents are the next option. As evidence grows for their efficacy in tic reduction in combination with atypical neuroleptics, this class commonly now is chosen over the typical neuroleptics because the atypical agents are less likely to cause extrapyramidal effects such as restlessness or acute dystonic reactions. In addition, their risk for the development of tardive dyskinesia is considered to be substantially less relative to typical neuroleptics. However, adverse effects, including significant weight gain, sedation, "foggy" thinking, gynecomastia, and glucose intolerance with the risk for diabetes mellitus, are frequent and often poorly tolerated. Alternative classes of agents, such as benzodiazepines, are sometimes helpful.Botulinum toxin can be useful for an isolated severe tic when injected by a neurologist directly into the offending muscle group. Its therapeutic impact is limited to the injected anatomic region and lasts about 3 months. Of course, any desired function of the affected muscle group also is curtailed by this intervention.When present, ADHD often imposes more severe functional interference than do tics. Stimulant medications are the first-line agents in the treatment of ADHD, even when comorbid with tic disorders. Until recently, the presence of TS contraindicated the use of stimulants for the treatment of ADHD in clinical practice, and the Physicians' Desk Reference continues to list motor tics and family history or diagnosis of TS among their contraindications. The assumptions of tic induction or exacerbation with stimulant use have been reinforced by case reports dating to the 1970s as well as by the natural time courses for the emergence of symptoms of ADHD (prior to age 7 years) and tics (around age 7 years), respectively. As such, the concomitant introduction of stimulant medication in a patient at approximately the time that she or he might otherwise have been destined to develop tics or perhaps during a natural waxing phase reinforces the impression of causality.In addition, stimulant medications work by increasing dopamine neurotransmission, and because dopamine-blocking agents decrease tics, it is reasonable to assume that stimulants increase tics. However, data from recent placebo-controlled studies simply do not support this prohibition for most patients. Nevertheless, it is a sensible and safer practice to alert families to the possibility of tic appearance or exacerbation in children who have tics. For some children, tics increase and may not decrease, as can be the nature of tic disorders. Families must understand this, and counseling should emphasize that stimulants do not cause tics de novo or permanently increase tic severity. Reminding families of the natural waxing and waning feature of tics as well as raising awareness of predictable environmental influences that may increase tics, such as stresses imposed by excitement, a holiday, or the beginning of a school year, may help to assuage apprehensions during inevitable upsurges.Standard stimulant dosing schedules and customary medical precautions apply. Nonstimulant medications also are available for the treatment of ADHD, including alpha-2-adrenergic agonists, tricyclic antidepressants, and newer antidepressants. For some patients, combined treatment with a stimulant and alpha-2-adrenergic agonist may provide improved outcomes relative to either agent alone. There now is some evidence that treating ADHD with the selective norepinephrine reuptake inhibitor atomoxetine may reduce tic severity.The selective serotonin reuptake inhibitors (SSRIs) are the first-line agents for the treatment of comorbid OCD. Currently, no specific SSRI shows unique advantages. Their effectiveness may be enhanced when used in combination with CBIT, particularly exposure and response prevention. Second-line agents, such as clomipramine, may be chosen when patients fail two SSRI trials. Families must be made aware of the United States Food and Drug Administration "black box" warning regarding the use of antidepressants in children and adolescents. Useful support for families and practitioners has been prepared by The American Psychiatric Association and the American Academy of Child and Adolescent Psychiatry and is available at http://ParentsMedGuide.org.Long-term prognosis in TS has not been well studied, in large part because the condition was considered rare until very recently. However, available data and clinical experience reveal that chronic tic disorders wax and wane regardless of intervention and most often improve substantially or resolve entirely in mid-to-late adolescence. The likelihood of the patient experiencing ongoing severe tics in adulthood is low. The greater prognostic risks for continued challenges and disability are seen not in tics but rather in comorbid conditions, such as ADHD, OCD, LD, anxiety, depression, and poor anger control. Competent interpersonal and coping skills with effective behavioral and emotional self-control afford tremendous support toward a positive psychosocial outcome, irrespective of disease severity or course. Therefore, identifying and building these qualities should form the backbone of any management design.Stereotypies are patterned, repetitive, purposeless, involuntary movements that also are rhythmic and continual and tend to change little over time. In contrast, tics are nonrhythmic and discrete, typically change in location and type over time, and wax and wane in frequency and severity. Examples of stereotypies include body rocking, head nodding, walking in circles, hand flapping or clapping, finger wiggling, and facial grimacing. Some stereotyped movements may occur in the setting of object manipulations, including spinning or twirling items, but manipulation of objects is not required for stereotypies to be identified as such. Other terms have been used to describe stereotypies, including "rhythmic habit patterns," "gratification phenomena," "self-stimulation," and "motor rhythmias."Stereotypies are associated most commonly with autism and other developmental disabilities. Indeed, stereotypies are present in most autistic children. Stereotypies also may be seen in children who have sensory impairments, specifically in blind or deaf children. Furthermore, stereotypies may occur in children subjected to severe environmental deprivation or restriction. However, stereotypies also occur in children who have no developmental disabilities, sensory impairments, or social deprivation.Unfortunately, few data exist on the natural history of stereotypies. Stereotyped, repetitive, rhythmic movements are common and, indeed, characteristic of infants and toddlers. Particular types of stereotypy develop in correlation with motor development. In most children, such movements decrease and ultimately cease. Stereotypies typically are present before 3 years of age in both autistic and nonautistic children. As children get older, stereotypies may diminish but can persist into adulthood in both autistic and nonautistic children.The neurobiologic mechanisms underlying stereotypies are not known. However, there are reasons to think that like most other involuntary movements, they arise from the basal ganglia or from cortical-basal ganglia-thalamocortical circuits. There may be important roles for dopamine and serotonin in the maintenance of stereotyped repetitive behaviors as well.Stereotypies are associated most commonly with developmental disabilities. However, it has been estimated that stereotypies occur in up to 7% of nondisabled children. The term "physiologic stereotypies" has been suggested when the movements occur in otherwise healthy children. Typical stereotypies include repeated, recurrent raising and lowering of the arms, flapping, waving, wrist rotation, and finger wiggling. Such motions often are accompanied by facial movements or grimacing. Physiologic stereotypies may be present in any setting but occur most commonly when the child is excited, mentally engaged, stressed, or bored and may increase with fatigue. A hallmark of stereotypies is that they usually cease when the child is distracted or engaged in a new activity. Most children appear to be unaware of the stereotypies.The typical age of onset for physiologic stereotypies is younger than 2 years. These motions are more common in boys (almost 2:1). Unlike tics, stereotypies tend not to change in anatomic location or complexity over time. Stereotypies are not preceded by an urge or thought, as is common with tics or compulsions. Physiologic stereotypies last for many years in most children. In some children, they disappear over time; in others, they persist into adulthood. There may be an increased incidence of ADHD or LD among children who have stereotypies.When approaching the treatment of stereotypies in any child, the first question should be whether to treat. If the behaviors are not causing discomfort, injury, or social impairment, it may be preferable not to treat them. If they are causing difficulty, treatment may be indicated. Treatments include pharmacologic and behavioral approaches.Many pharmacologic treatments have been reported in single cases or in small series. However, most are small, open-label designs subject to the usual problems of such studies, that is, placebo effect and observer bias. Clomipramine, risperidone, and fluoxetine have been shown to reduce repetitive behaviors in children and adolescents who have autism. However, there has been no systematic study of pharmacologic therapy in nonautistic children. Our clinical experience is that pharmacotherapy with available agents is of limited use in the treatment of stereotypies. The evidence for behavioral treatment with habit reversal therapy and differential reinforcement of other behaviors is a bit stronger, but still is preliminary (see Miller and associates in Suggested Reading).