Definition of Motor Stereotypy
Does your child bang his or her head repeatedly, rock back and forth, flap their hands, or even bite their fingernails? If so, your child might be exhibiting symptoms of motor stereotypy. The loose definition of motor stereotypy is a repetitive action that serves no function, and these actions fit that criteria. This definition includes those who experience these repetitive actions due to autism or other disabilities and conditions, as well as people who may have a negative drug interaction.
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), however, the disorder of motor stereotypy is not just a repetitive action that serves no function, it can also interfere with normal activities, or cause injury to the person doing it. To be diagnosed with motor stereotypy, it must last for longer than 4 weeks, and cannot be caused by drug usage, a medical condition, or a developmental disorder.
Complex vs. Common Motor Stereotypy
Psychologists tend to divide those afflicted by this disorder into two different categories: common/complex stereotypes, and primary/secondary stereotypes. Common stereotypes are far more common than complex stereotypes, and include nail biting, tooth grinding, and similar habits. Complex stereotypes, on the other hand, usually consist of limb movements such as hand flapping, and are far more socially jarring. Outside of these two categories lies the stereotypy of head nodding, which does not fill all of the requirements of either category, but shares many characteristics with complex stereotypes.
Primary vs. Secondary Stereotypy
Stereotypies can also be categorized as primary or secondary. Primary stereotypes are those that are found in children who are otherwise completely normal developmentally. Secondary stereotypes, on the other hand, are those that are found in children with some other neurologic or behavioral disorder, such as autism, mental retardation, schizophrenia, or OCD.
Think of it like this: Imagine you’re looking at two kids. Both of them are flapping their hands in front of their faces (a stereotypy). One of them has autism; the other does not.
The stereotypes look the same, but the first child is exhibiting a secondary stereotypy because it is related to an outside cause - in this case, autism. The second child is exhibiting a primary stereotypy.
The Difference Between Motor Stereotypies and Tics
People often confuse tics and motor stereotypes, as they look very similar. There are several characteristics, however, that can distinguish one from the other. For example, stereotypes begin at an earlier age (usually before age three), whereas tics usually begin between the ages of five and seven. Each stereotypic movement tend to last longer than a tic, and has more of a rhythmic feel. In addition, when a child exhibiting stereotypes is distracted or redirected, the stereotypes immediately stop; tics do not stop due to distraction.
Other Facts About Motor Stereotypy
Although researchers do not yet know what causes motor stereotypy, there seems to be some genetic component. Stereotypy does not cause or contribute to autism or other conditions, and the only real treatment appears to be behavioral therapy, which should be performed by a professional therapist.
Most children will retain some level of the stereotypy without treatment, with one Johns Hopkins University study showing that only 3-5% of students completely resolved their stereotypy without outside intervention.
This post is part of the series: Dealing With Perseveration in Autistic Children
Does your child or student with autism perseverate? If so, this series contains articles that can help you. They focus on dealing with perseveration in autistic children, and include descriptions of perseverative behavior and how to respond to them.