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Motor Disorders and Habits
Motor disorders are interrelated sets of psychiatric symptoms characterized by abnormal motor movements and associated phenomena. In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), motor disorders include tic, stereotypic movement, and developmental coordination disorders. Tic disorders (Tourette, persistent motor or vocal tic, provisional tic, other specified/unspecified tic) and stereotypic movement disorder are addressed in this chapter, along with habits. Although not DSM-5 motor disorders, habits present as repetitive and often problematic motor behaviors (e.g., thumb sucking, teeth grinding).
Tic Disorders
Tourette disorder (TD) , persistent (chronic) motor or vocal tic disorder (PTD) , and provisional tic disorders are characterized by involuntary, rapid, repetitive, single or multiple motor and/or vocal/phonic tics that wax and wane in frequency but have persisted for >1 yr since first tic onset (<1 yr for provisional tic disorder) ( Table 37.1 ). PTD is differentiated from TD in that PTD is limited to either motor or vocal tics (not both), whereas TD has both motor and vocal tics at some point in the illness (although not necessarily concurrently). The tic disorders are hierarchical in order (i.e., TD followed by PTD followed by provisional tic disorder), such that once a tic disorder at one level of the hierarchy is diagnosed, a lower-hierarchy diagnosis cannot be made. Other specified/unspecified tic disorders are presentations in which symptoms characteristic of a tic disorder that cause significant distress or impairment predominate but do not meet the full criteria for a tic or other neurodevelopmental disorder.
Table 37.1
Adapted from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (Copyright 2013). American Psychiatric Association, p. 81.
DSM-5 Diagnostic Criteria for Tic Disorders
-
Note: A tic is a sudden, rapid, recurrent, nonrhythmic motor movement or vocalization.
Tourette Disorder
- 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 may wax and wane in frequency but have persisted for >1 yr since first tic onset.
- C
Onset is before age 18 yr.
- D
The disturbance is not attributable to the physiologic effects of a substance (e.g., cocaine) or another medical condition (e.g., Huntington disease, postviral encephalitis).
Persistent (Chronic) Motor or Vocal Tic Disorder
- A
Single or multiple motor or vocal tics have been present during the illness, but not both motor and vocal.
- B
The tics may wax and wane in frequency but have persisted for >1 yr since first tic onset.
- C
Onset is before age 18 yr.
- D
The disturbance is not attributable to the physiologic effects of a substance (e.g., cocaine) or another medical condition (e.g., Huntington disease, postviral encephalitis).
- E
Criteria have never been met for Tourette disorder.
-
Specify if:
-
With motor tics only
-
With vocal tics only
-
Provisional Tic Disorder
- A
Single or multiple motor and/or vocal tics.
- B
The tics have been present for <1 yr since first tic onset.
- C
Onset is before age 18 yr.
- D
The disturbance is not attributable to the physiologic effects of a substance (e.g., cocaine) or another medical condition (e.g., Huntington disease, postviral encephalitis).
- E
Criteria have never been met for Tourette disorder or persistent (chronic) motor or vocal tic disorder.
Description
Tics are sudden, rapid, recurrent, nonrhythmic motor movements or vocalizations. Simple motor tics (e.g., eye blinking, neck jerking, shoulder shrugging, extension of the extremities) are fast, brief movements involving one or a few muscle groups. Complex motor tics involve sequentially and/or simultaneously produced, relatively coordinated movements that can seem purposeful (e.g., brushing back one's hair bangs, tapping the foot, imitating someone else's movement [ echopraxia ], or making a sexual or obscene gesture [ copropraxia ]). Simple vocal tics (e.g., throat clearing, sniffing, coughing) are solitary, meaningless sounds and noises. Complex vocal tics involve recognizable word or utterances (e.g., partial words [syllables], words out of context, coprolalia [obscenities or slurs], palilalia [repeating one's own sounds or words], or echolalia [repeating the last heard word or phrase]).
Sensory phenomena (premonitory urges) that precede and trigger the urge to tic have been described. Individuals with tics can suppress them for varying periods of time, particularly when external demands exert their influence, when deeply engaged in a focused task or activity, or during sleep. Tics are often suggestible and are worsened by anxiety, excitement, or exhaustion. Parents have described increasing frequency of tics at the end of the day. Research has not supported volitional suppressing of tics leading to tic rebound.
Clinical Course
Onset of tics is typically between ages 4 and 6 yr. The frequency of tics tends to wax and wane with peak tic severity between ages 10 and 12 yr and marked attenuation of tic severity in most individuals (65%) by age 18-20 yr. A small percentage will have worsening tics into adulthood. New onset of tics in adulthood is very rare and most often is associated with exposure to drugs or insults to the central nervous system. Tics manifest similarly in all age-groups and changes in affected muscle groups and vocalizations occur over time. Some individuals may have tic-free periods of weeks to months.
Epidemiology
Prevalence rates for all tics range from 6–18% for boys and 3–11% for girls, with the rate of TD alone estimated as 0.8%. In general, PTD/TD has a male preponderance with a gender ratio varying from 2 : 1 to 4 : 1. Evidence supports higher rates in white youth than black or Hispanic youth.
Differential Diagnosis
The differential diagnosis includes the repetitive movements of childhood ( Table 37.2 ). Tics may be difficult to differentiate from stereotypies. Although stereotypies may resemble tics, stereotypies are typically rhythmic movements and do not demonstrate the change in body location or movement type over time that is typical of tics. Compulsions may be difficult to differentiate from tics when tics have premonitory urges. Tics should be differentiated from a variety of developmental and benign movement disorders (e.g., benign paroxysmal torticollis, Sandifer syndrome, benign jitteriness of newborns, shuddering attacks). Tics may present in various neurologic illnesses (e.g., Wilson disease, neuroacanthocytosis, Huntington syndrome, various frontal-subcortical brain lesions), but it is rare for tics to be the only manifestation of these disorders.
Table 37.2
Repetitive Movements of Childhood
Adapted from Murphy TK, Lewin AB, Storch EA, et al: Practice parameter for the assessment and treatment of children and adolescents with chronic tic disorders, J Am Acad Child Adolesc Psychiatry 52(12):1341–1359, 2013.
| MOVEMENT | DESCRIPTION | TYPICAL DISORDERS WHERE PRESENT |
|---|---|---|
| Tics | Sudden rapid, recurrent, nonrhythmic, stereotyped, vocalization or motor movement | Transient tics, Tourette disorder, persistent tic disorder |
| Dystonia | Involuntary, sustained, or intermittent muscle contractions that cause twisting and repetitive movements, abnormal postures, or both | DYT1 gene, Wilson disease, myoclonic dystonia, extrapyramidal symptoms caused by dopamine-blocking agents |
| Chorea | Involuntary, random, quick, jerking movements, most often of the proximal extremities, that flow from joint to joint. Movements are abrupt, nonrepetitive, and arrhythmic and have variable frequency and intensity | Sydenham chorea, Huntington chorea |
| Stereotypies | Stereotyped, rhythmic, repetitive movements or patterns of speech, with lack of variation over time | Autism, stereotypic movement disorder, intellectual disability |
| Compulsions | A repetitive, excessive, meaningless activity or mental exercise that a person performs in an attempt to avoid distress or worry | Obsessive-compulsive disorder, anorexia, body dysmorphic disorder, trichotillomania, excoriation disorder |
| Myoclonus | Shock-like involuntary muscle jerk that may affect a single body region, one side of the body, or the entire body; may occur as a single jerk or repetitive jerks | Hiccups, hypnic jerks, Lennox-Gastaut syndrome, juvenile myoclonic epilepsy, mitochondrial encephalopathies, metabolic disorders |
| Akathisia | Unpleasant sensations of “inner” restlessness, often prompting movements in an effort to reduce the sensations | Extrapyramidal adverse effects from dopamine-blocking agents; anxiety |
| Volitional behaviors | Behavior that may be impulsive or caused by boredom, such as tapping peers or making sounds (animal noises) | Attention-deficit/hyperactivity disorder, oppositional defiant disorder, sensory integration disorders |
Individuals presenting with tics in the context of declining motor or cognitive function should be referred for neurologic assessment. Substances/medications that are reported to worsen tics include selective serotonin reuptake inhibitors (SSRIs), lamotrigine, and cocaine. If tics develop in close temporal relationship to the use of a substance or medication and then remit when use of the substance is discontinued, a causal relationship is possible. Although a long-standing clinical concern, controlled studies show no evidence that stimulants commonly increase tics.
Comorbidities
Comorbid psychiatric disorders are common, often with both patient and family viewing the accompanying condition as more problematic than the tics. There is a bidirectional association between PTD/TD (especially TD) and obsessive-compulsive disorder (OCD), with 20–60% of TD patients meeting OCD criteria and 20–40% of OCD patients reporting tics ( Fig. 37.1 ). Attention-deficit/hyperactivity disorder (ADHD) occurs in approximately 50% of all childhood PTD/TD, but estimates in clinically referred patients suggest much higher rates (60–80%). PTD/TD is often accompanied by behavior problems, including poor frustration tolerance, temper outbursts, and oppositionality. Learning disabilities have been found in >20% of these patients. Concurrent anxiety and depression have also been observed. Some patients with PTD/TD will display symptoms of autism spectrum disorder (ASD); careful assessment is required to determine which disorder is primary.
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