Motor Disorders

The DSM-5 motor disorders include developmental coordination disorder; stereotypic movement disorder; and the tic disorders of Tourette’s Disorder, persistent (chronic) motor or vocal tic disorder, and provisional tic disorder.

Motor disorders are malfunctions of the nervous system that cause involuntary or uncontrollable movements or actions of the body. These disorders can cause lack of intended movement or an excess of involuntary movement. Symptoms of motor disorders include tremors, jerks, twitches, spasms, contractions, or gait problems.

Causes of Motor Disorders

Pathological changes of certain areas of the brain are the main causes of most motor disorders. Causes of motor disorders by genetic mutation usually affect the cerebellum. The way humans move requires many parts of the brain to work together to perform a complex process. The brain must send signals to the muscles instructing them to perform a certain action. There are constant signals being sent to and from the brain and the muscles that regulate the details of the movement such as speed and direction, so when a certain part of the brain malfunctions, the signals can be incorrect or uncontrollable causing involuntary or uncontrollable actions or movements.

Developmental Coordination Disorder

Figure 1. Some possible signs of dyspraxia.

Developmental coordination disorder (DCD), also known as developmental motor coordination disorder, developmental dyspraxia, or simply dyspraxia, is a chronic neurological disorder beginning in childhood. It is also known to affect planning of movements and coordination as a result of brain messages not being accurately transmitted to the body. Impairments in skilled motor movements per a child’s chronological age interfere with activities of daily living. A diagnosis of developmental coordination disorder (DCD) is then reached only in the absence of other neurological impairments like cerebral palsy, multiple sclerosis, or Parkinson’s disease.

The DSM-5 criteria are as follows:

• Motor coordination will be greatly reduced, although the intelligence of the child is normal for the age.
• The difficulties the child experiences with motor coordination or planning interfere with the child’s daily life.
• The difficulties with coordination are not due to any other medical condition
• If the child also experiences comorbidities such as intellectual or other developmental disorder; motor coordination is still disproportionally affected.

Management

There is no cure for the condition. Instead, it is managed through therapy. Physical therapy or occupational therapy can help those living with the condition.

Some people with the condition find it helpful to find alternative ways of carrying out tasks or organizing themselves, such as typing on a laptop instead of writing by hand or using diaries and calendars to keep organized. A review completed in 2017 by Cochrane of task-oriented interventions for developmental coordination disorder (DCD) resulted in inconsistent findings and a call for further research and randomized controlled trials.

Epidemiology

DCD is a lifelong neurological condition that is more common in males than in females, with a ratio of approximately four males to every female. The exact proportion of people with the disorder is unknown since the disorder can be difficult to detect due to a lack of specific laboratory tests, thus making diagnosis of the condition one of elimination of all other possible causes/diseases. Approximatelyfive to 6% of children are affected by this condition.

Stereotypic Movement Disorder

Stereotyped movements are common in infants and young children; if the child is not distressed by movements and daily activities are not impaired, diagnosis is not warranted. When stereotyped behaviors cause significant impairment in functioning, an evaluation for stereotypic movement disorder is needed. There are no specific tests for diagnosing this disorder, although some tests may be ordered to rule out other conditions. Stereotyped movement disorder (SMD) may occur with Lesch–Nyhan syndrome, intellectual development disorder (intellectual disability), and fetal alcohol exposure or as a result of amphetamine intoxication.

When diagnosing stereotypic movement disorder, DSM-5 calls for specification of

• with or without self-injurious behavior,
• association with another known medical condition or environmental factor, and
• severity (mild, moderate, or severe).

Common repetitive movements of stereotyped movement disorder (SMD) include head banging, arm-waving, hand-shaking, rocking and rhythmic movements, self-biting, self-hitting, and skin-picking; other stereotypies are thumb-sucking, nail-biting, trichotillomania, bruxism, and abnormal running or skipping.

Epidemiology

Stereotyped movement disorder (SMD) occurs in about 3%-4% of children.^[1] Stereotypies often represent a physiological and transient finding, up to 60% of neurologically typical children showing some stereotypic movements or behaviors between two and five years. Therefore, SMD are classified as primary, indicating their presence in an otherwise typically developing child, or secondary, if another of the above-mentioned neuropsychiatric disorders is present.^[2] Although not necessary for the diagnosis, individuals with intellectual development disorder (intellectual disorder) are at higher risk for SMD. It is more common in boys and can occur at any age.

Management

Though we have yet to find a cure for these disorders, some studies have looked at the effectiveness of medication therapy but thus far (based on parent reports of medication trials) there haven’t been any medication therapy identified to be effective in treating symptoms. However, behavioral therapy appears to be beneficial for those with primary SMD. Researchers found that therapy that focuses on a mix of awareness and reinforcement of other behaviors helped reduce unwanted movement. Additionally, another study looked at the effectiveness of home-based, parent-administered behavioral therapy and this assessment showed significant improvement compared to the baseline.^[3]

Tic Disorders

Tourette Syndrome (TS or Tourette’s)

To be diagnosed with Tourette syndrome (TS or Tourette’s), a person must have

• two or more motor tics (for example, blinking or shrugging the shoulders) and at least one vocal tic (for example, humming, clearing the throat, or yelling out a word or phrase), although they might not always happen at the same time.
• had tics for at least a year. The tics can occur many times a day (usually in bouts) nearly every day or off and on.
• tics that begin before age 18 years.
• symptoms that are not due to taking medicine or other drugs or due to having another medical condition (for example, seizures, Huntington disease, or postviral encephalitis).

Figure 2. Coughing is a common tic.

Tourette syndrome or Tourette’s syndrome (TS or Tourette’s) is a common neurodevelopmental disorder that begins in childhood or adolescence. It is characterized by multiple movement (motor) tics and at least one vocal (phonic) tic. Common tics are blinking, coughing, throat clearing, sniffing, and facial movements. These are typically preceded by an unwanted urge or sensation in the affected muscles, can sometimes be suppressed temporarily, and characteristically change in location, strength, and frequency. Tourette’s is at the more severe end of a spectrum of tic disorders. The tics often go unnoticed by casual observers.

Tourette’s was once regarded as a rare and bizarre syndrome and has popularly been associated with coprolalia (the utterance of obscene words or socially inappropriate and derogatory remarks). It is no longer considered rare; about 1% of school-age children and adolescents are estimated to have Tourette’s, and coprolalia occurs only in a minority. There are no specific tests for diagnosing Tourette’s; it is not always correctly identified because most cases are mild and the severity of tics decreases for most children as they pass through adolescence. Therefore, many go undiagnosed or may never seek medical attention. Extreme Tourette’s in adulthood, though sensationalized in the media, is rare, but for a small minority, severely debilitating tics can persist into adulthood. Tourette’s does not affect intelligence or life expectancy.

Tourette syndrome was named by French neurologist Jean-Martin Charcot for his intern, Georges Gilles de la Tourette, who published in 1885 an account of nine patients with a “convulsive tic disorder.” While the exact cause is unknown, it is believed to involve a combination of genetic and environmental factors. The mechanism appears to involve dysfunction in neural circuits between the basal ganglia and related structures in the brain.

Persistent (Chronic) Motor or Vocal Tic Disorder

To be diagnosed with a persistent tic disorder, a person must

• have one or more motor tics (for example, blinking or shrugging the shoulders) or vocal tics (for example, humming, clearing the throat, or yelling out a word or phrase), but not both.
• have tics that occur many times a day nearly every day or on and off throughout a period of more than a year.
• have tics that start before age 18 years.
• have symptoms that are not due to taking medicine or other drugs or due to having a medical condition that can cause tics (for example, seizures, Huntington disease, or postviral encephalitis).
• not have been diagnosed with Tourette’s.

Provisional Tic Disorder

To be diagnosed with a provisional tic disorder, a person must

• have one or more motor tics (for example, blinking or shrugging the shoulders) or vocal tics (for example, humming, clearing the throat, or yelling out a word or phrase).
• have been present for no longer than 12 months in a row.
• have tics that start before age 18 years.
• have symptoms that are not due to taking medicine or other drugs or due to having a medical condition that can cause tics (for example, Huntington disease or postviral encephalitis).
• not have been diagnosed with Tourette’s or persistent motor or vocal tic disorder.

Epidemiology

Tic disorders are more common among males than females. At least one in five children experience some form of tic disorder, most frequently between the ages of seven and twelve. As many as one in 100 people may experience some form of tic disorder, usually before the onset of puberty.

Treatment of Tic Disorders

There is no cure for Tourette’s and no single most effective medication. In most cases, medication for tics is not necessary, and behavioral therapies are the first-line treatment. Education is an important part of any treatment plan, and explanation alone often provides sufficient reassurance that no other treatment is necessary. Among those who are referred to specialty clinics, other conditions like ADHD and OCD are more likely than in the broader population of persons with Tourette’s. These co-occurring diagnoses often cause more impairment to the individual than the tics; hence it is important to correctly distinguish co-occurring conditions and treat them.