Stereotypic movement disorder
Stereotypic movement disorder is a disorder characterized by repeated, rhythmic, purposeless movements or activities such as head banging, nail biting, or body rocking. These movements either cause self-injury or severely interfere with normal activities. Until 1994, the American Psychiatric Association referred to stereotypic movement disorder as stereotypy/habit disorder.
Stereotypic movements were first described as a psychiatric symptom in the early 1900s. Since then, they have been recognized as a symptom of both psychotic and neurological disorders. They may also arise from unexplained causes. These movements may include:
- head banging
- nail biting
- playing with hair (but not hair pulling, which is considered the separate disorder of trichotillomania)
- thumb sucking
- hand flapping
- nose picking
- body rocking
- picking at the body
- object biting
- compulsive scratching
- eye gouging
- teeth grinding (bruxism)
- breath holding
- stereotyped sound production
The precise definition of stereotypic movement disorder has changed over the past 20 years. Today, it limits the disorder to repetitive movements that cause physical harm or severely interfere with normal activities. These movements cannot be better described by another psychiatric condition such as anxiety disorder, a general medical condition such as Huntington's disease, or as the side effect of a medication or illicit drug (for example, cocaine use).
Stereotypic movements occur in people of any age, including the very young, but they are most prevalent in adolescence. People may exhibit only one particular stereotyped movement or several. The movements may be slow and gentle, fast and frenetic, or varied in intensity. They seem to increase with boredom, tension, or frustration, and it appears that the movements are self-stimulatory and sometimes pleasurable. The root causes are unknown.
Stereotypic movements are common in infants and toddlers. Some estimates suggest that 15–20 percent of children under age three exhibit some kind of rhythmic, repetitive movements. Certainly thumb sucking and body rocking are common self-comforting mechanisms in the very young. This type of repeated movement is temporary, and usually ends by age three or four. It is not the same as stereotypic movement disorder.
Stereotypic movements can be caused by:
- sensory deprivation (blindness or deafness)
- drug use (cocaine, amphetamines)
- brain disease (seizures, infection)
- major psychiatric disorders (anxiety disorder, obsessive-compulsive disorder, autism)
- mental retardation
It has also been suggested that inadequate caregiving may cause the disorder. Although many situations can give rise to stereotypic movements, the root cause of stereotypic movement disorder is unknown. Different theories propose that the causes are behavioral, neurological, and/or genetic. Although there are many theories to account for this disorder, no hard evidence clearly supports one line of reasoning or specific cause.
Symptoms of stereotypic movement disorder include all the activities listed above. It should be noted that many of these activities are normal in infants. They usually begin between five and 11 months, and disappear on their own by age three. In fact, about 55% of infants grind their teeth. These passing phases of repetitive movement in infants are not the same as stereotypic movement disorder. They do not cause harm, and often serve the purpose of self-comforting or helping the child learn a new motor skill.
People with stereotypic movement disorder often hurt themselves. They may pick their nail cuticles or skin until they bleed. They may repeatedly gouge their eyes, bite or hit themselves causing bleeding, bruising, and sometimes, as in the case of eye gouging or head banging, even more severe damage. Some people develop behaviors such as keeping their hands in their pockets, to prevent these movements. In other cases those who hurt themselves appear to welcome, rather than fight, physical restraints that keep them safe. However when these restraints are removed, they return to their harmful behaviors.
Stereotypic movement disorder is most strongly associated with severe or profound mental retardation, especially among people who are institutionalized and perhaps deprived of adequate sensory stimulation. It is estimated that 2–3% of people with mental retardation living in the community have stereotypic movement disorder. About 25% of all people with mental retardation who are institutionalized have the disorder. Among those with severe or profound retardation, the rate is about 60%, with 15% showing behavior that causes self-injury.
Stereotypic movements are common among children with pervasive developmental disorderssuch as autism, childhood degenerative disorder, and Asperger's disorder. These movements can also be seen in people with Tourette's disorder or with tics. Head banging is estimated to affect about 5% of children, with boys outnumbering girls three to one, although other stereotypic behaviors appear to be distributed equally between males and females. Despite its association with psychiatric disorders, there are some people with normal intelligence and adequate caregiving who still develop stereotypic movement disorder.
Stereotypic movements are diagnosed by the presence of the activities mentioned above. Young children rarely try to hide these movements, although older children may, and the first sign of them may be the physical harm they cause (bleeding skin, chewed nails). Often parents mention these repetitive movements when the physician takes a history of the child.
The difficulty in diagnosing stereotypic movement disorder comes from distinguishing it from other disorders where rhythmic, repetitive movements occur. To be diagnosed with stereotypic movement disorder, the following conditions must be met:
- The patient must show repeated, purposeless motor behavior.
- The patient must experience physical harm from this behavior or it must seriously interfere with activities.
- If the patient is mentally retarded, the behavior must be serious enough to need treatment.
- The behavior must not be a symptom of another psychiatric disorder.
- The behavior must not be a side effect of medicinal or illicit substance use.
- The behavior must not be caused by a diagnosed medical condition.
- The behavior must last at least four weeks. The disorder may be classified as either with self-injurious behavior or without self-harm.
This definition of stereotypic movement disorder rules out many people who show repetitive movement because of autism or other pervasive developmental disorders. It also rules out those with obsessive-compulsive disorder, where movements are apt to be ritualistic and follow rigid rules or patterns. In addition, specific disorders such as trichotillomania (hair pulling) do not fall under the diagnosisof stereotypic movement disorder, nor do developmentally appropriate self-stimulatory behavior among young children, such as thumb sucking, rocking or transient pediatric head banging.
There are few successful treatments for stereotypic movement disorder. When the patient harms himself, physical restraints may be required. In less severe situations, behavioral modifications using both rewards and punishments may help decrease the intensity of the behavior. Drugs that have been used with some success to treat stereotypic movement disorder include clomipramine(Anafranil), desipramine(Norpramin), haloperidol(Haldol) and chlorpromazine(Thorazine).
Stereotypic movements peak in adolescence, then decline, and sometimes disappear. Although behavior modificationmay reduce the intensity of the stereotypic movements, rarely does it completely eliminate them. Stressand physical pain may bring on these movements, (which may come and go for years), especially among those patients with severe mental retardation.
Stereotypic movement disorder cannot be prevented. Interventions should be done to prevent self-injury.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders.4th ed. text revised. Washington DC: American Psychiatric Association, 2000.
Hales, Robert E., Stuart C. Yudofsky, and John A. Talbot. The American Psychiatric Press Textbook of Psychiatry.3rd ed. Washington, DC: American Psychiatric Press, 2000.
Sadock, Benjamin J. and Virginia A. Sadock, eds. Comprehensive Textbook of Psychiatry.7th ed. Vol. 2. Philadelphia: Lippincott Williams and Wilkins, 2000.
Tish Davidson, A.M.