Stereotypic movement disorder (SMD) is a
motor disorder with onset in childhood involving restrictive and/or repetitive, nonfunctional motor behavior (e.g., hand waving or head banging), that markedly interferes with normal activities or results in bodily injury.
To be classified as SMD, the behavior in question must not be due to the direct effects of a substance,
autism
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
, or another medical condition.
[ The cause of this disorder is not known.]
Signs and symptoms
Common repetitive movements of SMD include head banging, arm waving, hand shaking, rocking and rhythmic movements, self-biting, self-hitting, and skin-picking;[ other stereotypies are thumb-sucking, dermatophagia, nail biting, ]trichotillomania
Trichotillomania (TTM), also known as hair-pulling disorder or compulsive hair pulling, is a mental disorder characterized by a long-term urge that results in the pulling out of one's own hair. A brief positive feeling may occur as hair is remov ...
, bruxism
Bruxism is excessive teeth grinding or jaw clenching. It is an oral parafunctional activity; i.e., it is unrelated to normal function such as eating or talking. Bruxism is a common behavior; reports of prevalence range from 8% to 31% in the gen ...
and abnormal running or skipping.
Cause
The cause of stereotypic movement disorder is unknown.
Diagnosis
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 warranted. There are no specific tests for diagnosing this disorder, although some tests may be ordered to rule out other conditions. SMD may occur with Lesch–Nyhan syndrome, intellectual disability, ]Autistic Spectrum Disorder
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
, 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
Self-harm is intentional behavior that is considered harmful to oneself. This is most commonly regarded as direct injury of one's own skin tissues usually without a suicidal intention. Other terms such as cutting, self-injury and self-mutilati ...
;
* association with another known medical condition or environmental factor;
* severity (mild, moderate or severe).[
]
Classification
Stereotypic movement disorder is classified in the fifth revision of the ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM-5
The ''Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition'' (DSM-5), is the 2013 update to the '' Diagnostic and Statistical Manual of Mental Disorders'', the taxonomic and diagnostic tool published by the American Psychiatri ...
) as a motor disorder, in the category of neurodevelopmental disorder
Neurodevelopmental disorders are a group of disorders that affect the development of the nervous system, leading to abnormal brain function which may affect emotion, learning ability, self-control, and memory. The effects of neurodevelopmenta ...
s.[
]
Differential diagnosis
Other conditions which feature repetitive behaviors in the differential diagnosis include autism spectrum disorder
The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...
s, obsessive–compulsive disorder
Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...
, tic disorder
Tic disorders are defined in the ''Diagnostic and Statistical Manual of Mental Disorders'' (DSM) based on type (motor or phonic) and duration of tics (sudden, rapid, nonrhythmic movements). Tic disorders are defined similarly by the World Health ...
s (e.g., Tourette syndrome
Tourette syndrome or Tourette's syndrome (abbreviated as 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) ...
), and other conditions including dyskinesia
Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of ...
s.[
Stereotypic movement disorder is often misdiagnosed as tics or ]Tourette syndrome
Tourette syndrome or Tourette's syndrome (abbreviated as 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) ...
(TS). Unlike the tics of TS, which tend to appear around age six or seven, repetitive movements typically start before age three,[ are more bilateral than tics, and consist of intense patterns of movement for longer runs than tics. Tics are less likely to be stimulated by excitement. Children with stereotypic movement disorder do not always report being bothered by the movements as a child with tics might.][ A blog by Roger Freeman, MD, clinical head of the Neuropsychiatry Clinic, ]British Columbia's Children's Hospital
British Columbia Children's Hospital is a medical facility located in Vancouver, British Columbia, and is an agency of the Provincial Health Services Authority. It specializes in health care for patients from birth to 16 years of age (possibly l ...
, professional advisory board member of the Tourette Syndrome Foundation of Canada
Tourette Canada (formerly Tourette Syndrome Foundation of Canada) is a Canadian voluntary organization based in Mississauga, Ontario. It was formed in 1976, and is dedicated to improving the quality of life for those with or affected by Tourette sy ...
, and former member of the Tourette Syndrome Association Medical Advisory Board.
Treatment
There is no consistently effective medication for SMD, and there is little evidence for any effective treatment.[ In non-autistic ]habit reversal training
Habit reversal training (HRT) is a "multicomponent behavioral treatment package originally developed to address a wide variety of repetitive behavior disorders".
Behavioral disorders treated with HRT include tics, trichotillomania, nail biting, ...
may be useful [ as well as decoupling.] No treatment is an option when movements are not interfering with daily life.[
]
Prognosis
Prognosis depends on the severity of the disorder. Recognizing symptoms early can help reduce the risk of self-injury, which can be lessened with medications. Stereotypic movement disorder due to head trauma may be permanent.[
]
Epidemiology
Although not necessary for the diagnosis, individuals with intellectual disability are at higher risk for SMD.[ It is more common in boys, and can happen at any age][
]
References
Further reading
*
External links
{{Emotional and behavioral disorders
Neurological disorders
Neurological disorders in children
Neurodevelopmental disorders