Module 9 – Motor-related Disorders

3rd edition as of August 2022

Module Overview

In Module 9, we will discuss matters related to motor-related disorders to include their clinical presentation, prevalence, comorbidity, etiology, assessment, and treatment options. Our discussion will include stereotypic movement and tic disorders. Be sure you refer to Modules 1-3 for explanations of key terms (Module 1), an overview of the various models to explain psychopathology (Module 2), and descriptions of the various therapies (Module 3).

Module Outline

• 9.1. Clinical Presentation
• 9.2. Prevalence and Comorbidity
• 9.3. Etiology
• 9.4. Assessment and Treatment

Module Learning Outcomes

• Describe how stereotypic movement disorder and tic disorders present.
• Describe the prevalence of stereotypic movement disorder and tic disorders.
• Describe the etiology of stereotypic movement disorder and tic disorders.
• Describe how stereotypic movement disorder and tic disorders are assessed, diagnosed, and treated.

9.1. Clinical Presentation

Section Learning Objectives

• Describe the presentation and associated features of stereotypic movement disorder.
• Describe the presentation and associated features of tic disorders.

9.1.1. Stereotypic Movement Disorder

Stereotypic movement disorder involves “repetitive, seemingly driven, and apparently purposeless motor behavior” such as hand flapping, body rocking, or hitting one’s own body (APA, 2022, pg. 89). Whether efforts to stop such movements are successful is questionable. For children that are developing typically, directing attention to the movements, or distracting them from performing the movements, are successful. For children with neurodevelopmental disorders, such efforts are less successful. The behavior displayed varies, but each child has their own signature or individually patterned behavior. Duration of the behavior is a few seconds to several minutes or longer, while the frequency can vary from many occurrences during a single day, to several weeks between episodes. The behaviors can occur during moments of boredom, excitement, stress, fatigue, or when the child is engrossed in other activities.

The stereotypic movements cause impairment in social, academic, or other activities and can result in self-injury. In fact, the mental health professional should specify if stereotypic movement disorder is with or without self-injurious behavior and whether the severity of the disorder is mild, moderate, or severe. A mild presentation is one in which the stereotypic movement is easily suppressed by a sensory stimulus or distraction. Severe presentation would be characterized by continuous movements that interfere with daily living. The onset of the disorder is during the early developmental period, typically within the first three years of life (APA, 2022).

9.1.2. Tic Disorders

Tic disorders consist of three separate diagnoses. The most commonly known of the three is Tourette’s disorder. The second diagnosis is persistent (chronic) motor or vocal tic disorder. The third is provisional tic disorder. We will start by discussing the tic disorders generally and then move to specifics of each.

     9.1.2.1. General symptoms. These disorders present before adulthood (i.e., 18 years old). Typically speaking, the time in which they present is between the ages of 4 and 6 and are most severe in symptomology between the ages of 10 and 12.

For all three disorders, tics are present. The DSM defines a tic as, “a sudden, rapid, recurrent, nonrhythmic motor movement or vocalization (APA, 2022, pg. 93).  Tics can be either motor movements (motor) or vocalizations (vocal). These can be simple, meaning they only involve one movement or vocalization, or they can be complex, meaning they involve multiple movements, vocalizations, or a combination of movements and vocalizations within the same tic. Tics are largely considered to be involuntary. It is common for tics to increase in severity for a period of time and then resolve or drastically reduce for a period of time (APA, 2022).

     9.1.2.2. Tourette’s disorder. Tourette’s disorder occurs when both motor and vocal tics are present. More than one motor tic must be present and at least one vocal tic must occur (APA, 2022) to be classified as Tourette’s disorder. The tics do not have to occur together and do not have to be complex tics. Though tics may increase and decrease in frequency, they will have persisted for more than one year since the first tic onset.

     9.1.2.3. Persistent (chronic) motor or vocal tic disorder. This is when either one or more motor tic or one or more vocal tic is present. However, vocal and motor tics are not both present (APA, 2022). These again can be simple or complex and only the presence of one tic is required. To receive this diagnosis, the individual must never have been diagnosed with Tourette’s disorder. The mental health professional will specify whether the disorder presents with motor tics only or with vocal tics only, and though tics may increase and decrease in frequency, they will have persisted for more than one year since first tic onset.

     9.1.2.4. Provisional tic disorder. This diagnosis is used if there are single or multiple motor and/or vocal tics, but they have been present for less than one year since first tic onset. The criteria for Tourette’s disorder or persistent (chronic) motor or vocal tic disorder will never have been met.

9.2. Prevalence and Comorbidity

Section Learning Objectives

• Describe the prevalence of stereotypic movement disorder and tic disorders.
• Describe common disorders that are comorbid with stereotypic movement disorder and tic disorders.

9.2.1. Stereotypic Movement Disorder

Stereotypic movement disorder is relatively rare, occurring in only about 3 to 4% of the general population. However, in individuals with intellectual developmental disorder (intellectual disability), the prevalence rate is higher and occurs in about 4 to 16% of individuals. The risk is greater in individuals with severe intellectual developmental disorder.

Stereotypic movement disorder is often comorbid with other genetic and biologically based disorders such fragile X syndrome, Rett syndrome, Lesch-Nyhan syndrome, as well as other related conditions (Oliver, Petty, Ruddick, & Bacarese-Hamilton, 2012). Additionally, the disorder is comorbid with ADHD, motor coordination problems, tics/Tourette’s disorder, and anxiety (APA, 2022).

     9.2.1.1. Differential diagnosis: autism spectrum disorder. Although the repetitive movements of stereotypic movement disorder may be reminiscent of behaviors seen in children with autism and may develop in the same developmental timeframe (e.g., around or before age 3) as autism spectrum disorder, children with stereotypic movement disorder do not display social communication and reciprocity deficits. Moreover, they do not have circumscribed interests, difficulty with transitions, delayed speech, etc. The only displayed symptom related to autism spectrum disorder is the stereotypy related to behavior. As the DSM says, “When autism spectrum disorder is present, stereotypic movement disorder is diagnosed only when there is self-injury or when the stereotypic behaviors are sufficiently severe to become a focus of treatment” (APA, 2022, pg. 91).

     9.2.1.2. Differential diagnosis: tic disorders. It may seem that distinguishing between a tic and stereotyped movement would be difficult. However, there are a few factors that help differentiate the two. For example, tics tend to be variable, meaning they change over time. Stereotyped movements, although they may change, tend to be more fixed and consistent. Moreover, stereotyped movements related to stereotypic movement disorder tend to present earlier in development (before age 3) than tics related to tic disorders do (mean age at onset 4-6 years). Finally, tics are typically quick, brief, and fleeting, whereas stereotypic movements tend to be more prolonged and repetitive (APA, 2022).

     9.2.1.3. Differential diagnosis: OCD. The absence of obsessions in stereotypic movement disorder distinguishes it from obsessive-compulsive disorder. As the DSM says, “In OCD the individual feels driven to perform repetitive behaviors in response to an obsession or according to rules that must be applied rigidly, whereas in stereotypic movement disorder the behaviors are seemingly driven but apparently purposeless” (APA, 2022, pg. 92).

OCD-related disorders of trichotillomania (e.g., pulling hair) and excoriation (e.g., picking at skin) may also seem difficult to differentiate from stereotypic movement disorder. However, in trichotillomania and excoriation, there tends to be a purpose for the behavior (e.g., extreme anxiety) and the behavior is not typically patterned or displayed in a rhythmic way. Whereas, in stereotypic movement disorder, the behaviors are more patterned or rhythmic. Stereotypic movement disorder has an earlier onset than OCD-related disorders, which tends to be around puberty or later (APA, 2022).

9.2.2. Tic Disorders

Tic disorders are relatively rare. The CDC estimates that approximately 0.3% of children are diagnosed with Tourette’s disorder (CDC, 2018) while the DSM reports an estimated 3 per 1,000 for the prevalence of clinically identified cases (APA, 2022). Tic disorders are more common in males, and there are lower rates in African American and Latinx individuals. Epidemiological studies have shown tics to occur in children from all continents (APA, 2022).

Comorbid disorders are common, with 86% of individuals with Tourette’s disorder also having another psychological disorder (CDC, 2018, October). ADHD, disruptive behavior, and OCD are commonly comorbid with tic disorders (APA, 2022) with about two-thirds of individuals with Tourette’s disorder also having ADHD and one-third having OCD (CDC, 2018, October).

In terms of differential diagnosis, tic disorders must be distinguished from OCD and related disorders. The compulsions of OCD attempt to prevent or reduce anxiety or distress and are usually performed in response to an obsession, while individuals with a tic disorder feel the need to perform the action in a particular fashion, equally on both sides of the body a specific number of times, or until a “just right” feeling is achieved. As for body-focused repetitive behavior disorders, they tend to be more goal-directed and complex than tics (APA, 2022).

9.3. Etiology

Section Learning Objectives

• Describe biological basis/causes of motor disorders.
• Describe environmental causes of motor disorders.

9.3.1. Biological

     9.3.1.1. Stereotypic movement disorder. Individuals with lower cognitive functioning are at higher risk for stereotypic movement disorder and have poorer response to interventions. Some medical conditions and genetic syndromes such as Lesch-Nyhan syndrome or Rett syndrome are at higher risk for stereotypies (APA, 2022). Little is known about the genetic and biological vulnerabilities that lead to stereotypic movement disorder (Zinner & Mink, 2010) though some evidence suggests the disorder to be somewhat heritable due to the high frequency of cases that have a positive family history of motor stereotypies (APA, 2022).

     9.3.1.2. Tic disorders. There is a strong heritability component for tic disorders. For example, research indicates there is up to a 50% chance that a parent with a genetic vulnerability for Tourette’s disorder will pass the genetic susceptibility on to their child (CDC, 2018, April) and the DSM estimates that the heritability of tic disorder is 70%-85% (APA, 2022). Additionally, it is hypothesized that tics may be triggered due to atypicalities in an individual’s ability to breakdown dopamine (CDC, 2018, April).

9.3.2. Environmental

     9.3.2.1 Stereotypic movement disorder. For stereotypic movement disorder, social isolation and lack of nurturing may lead an individual to attempt to self-stimulate and repetitive, stereotyped behaviors may develop (APA, 2022). Thus, similar to what was discussed with rumination disorder, stereotypic movements may be automatically reinforced due to the internal stimulation it provides (Ricketts, 2013). Environmental stress may trigger stereotypic behavior and fear may alter the physiological state which results in increased frequency of stereotypic behaviors.

     9.3.2.2. Tic disorders. In tic disorders, individuals may mimic the behavior of others, not as a way to mock them, but as a result of their disorder. Moreover, stressors may exacerbate symptoms of tics. As such, high levels of stress in an environment, increased excitement, or high levels of worry may lead to a higher frequency and intensity of tics. Some research also indicates that children whose mothers smoked while pregnant or experienced significant complications during pregnancy may have a higher risk for developing tics. Low birth weight may also be a risk factor for developing tics. Finally, some infections have been associated with later development of tics in children (CDC, 2018, April) and advanced parental age is a risk factor (APA, 2022).

9.4. Assessment and Treatment

Section Learning Objectives

• Describe how motor disorders are assessed and diagnosed.
• Describe treatment options for motor disorders.

9.4.1. General Assessment for Motor Disorders

Assessing for a motor disorder is done with observation and interviewing. Information is gathered about frequency, context, and severity, as well as the presence of voluntary versus involuntary movements. Some tools may be used to rule out other disorders, such as measures to screen/assess for autism spectrum disorder and OCD-related concerns. Additionally, medical assessments may be conducted to ensure that behaviors are not better captured by a medical condition.

9.4.2. Treatment of Stereotypic Movement Disorder

     9.4.2.1. Behavioral therapy. Less research has been conducted on treating stereotypic movement disorder. The most commonly researched and used intervention is behavioral therapy. Specifically, differential reinforcement or habit reversal therapy (described in CBITS intervention below) with modifications has shown promise (Rinker, 2013). When utilizing differential reinforcement, the specific method is often differential reinforcement of other behaviors (DRO) which is when delivery of a reinforcer is contingent on the absence of an undesirable behavior (a tic) for some period.

     9.4.2.2. Psychopharmacology. Medications including fluoxetine (a selective serotonin reuptake inhibitor), clomipramine (a tricyclic antidepressant), and risperidone (an atypical neuroleptic) have been noted to positively impact repetitive behaviors in children with autism spectrum disorder, and thus, are used with children diagnosed with stereotypic movement disorder at times. However, there is no evidence that these medications are empirically efficacious and beneficial in reducing stereotypy in children with stereotypic movement disorder (Zinner & Mink, 2010).

9.4.3. Treatment of Tic Disorders

     9.4.3.1. Psychotherapy. Comprehensive Behavioral Intervention for Tics (CBIT, Woods et al., 2008) is considered the most established and efficacious treatment for tics. The treatment utilizes habit reversal training which includes increasing awareness and then introducing an incompatible response to a behavior. CBIT treatment includes the core components of (1) increasing the individual’s awareness of tics, (2) establishing competing behaviors to use when an urge or tic begins, (3) increasing relaxation strategies, and (4) making changes to reduce situations and events that increase tics. As such, the treatment starts with awareness training. This includes having a child fully describe and understand each tic as well as identify different areas in the body the individual may feel “urges” in just before a tic. Next, the clinician and child will come up with competing responses to use when an urge to tic occurs, rendering engaging of the tic difficult or even impossible. An example of a competing response may be to clench one’s jaw and press their lips together for a tic that involves licking one’s lips. Finally, attempts to help an individual relax as well as reduce situations in which their tics increase (e.g., high stress, change in routines, etc.) are then focused on (Woods et al., 2008).

     9.4.3.2. Psychopharmacology.  Commonly prescribed medications include older classes of antipsychotics known as typical neuroleptics, newer classes of antipsychotics, known as atypical neuroleptics, and alpha-2-adrenergic agonists. Often, medical professionals will prescribe alpha-2-adrenergic agonists as a first step in medicinal intervention. It should be noted that it can take a few months before medication shows any notable improvement in tics. The next option may include atypical neuroleptics. Finally, as a last resort, a typical neuroleptic may be utilized. However, there are serious negative side-effects with these medications – some of which are not reversible. As such, these are used infrequently and with caution (Zinner & Mink, 2010).

It should be noted that tic disorders are frequently comorbid with ADHD, and thus, the treatment of ADHD with medication must be considered carefully. This is because the medications that are typically used to treat ADHD (i.e., stimulants), have a potential to have negative impacts on tics, partially due to the impact the stimulant medicine may have on dopamine. As such, professionals and families may choose to medicate ADHD with non-stimulant medicines if tics are also present. One non-stimulant option, alpha-2-adrenergic agonists, can be used to treat both ADHD and tics (Zinner & Mink, 2010).

Module Recap

In this module, we learned about stereotypic movement disorder and tic disorders. We discussed the various symptoms of motor disorders. We then discussed the prevalence of motor disorders and examined potential comorbid disorders. We then looked at the etiology of motor disorders. Finally, we discussed the process of assessing and treating these disorders.

This concludes our discussion of developmental delays and motor disorders. In our next part we will begin a discussion of behavior-related disorders, starting with attention-deficit/hyperactivity disorder.

3rd edition