Stereotypic Movement Disorder

What is stereotypic movement disorder?

Stereotypic movement disorder (SMD) involves repetitive and purposeless movements that happen in a specific pattern, like head banging and body rocking. The movements interfere with regular activity and/or may cause bodily harm.

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), stereotypic movement disorder happens when the behavior can’t be better explained by another diagnosis or the effects of substances or medications.

SMD typically begins before 3 years of age and continues into adulthood.

What are motor stereotypies?

Some people consider stereotypic movement disorder and motor stereotypies the same thing, but they’re different. It helps to know what motor (movement) stereotypies are and when healthcare providers consider them a disorder.

You can think of motor stereotypies as just actions or symptoms, and stereotypic movement disorder as a condition.

Providers classify motor stereotypies into two types:

• Simple motor stereotypies. These are very common behaviors in both children and adults that involve repetitive movements. Examples include thumb-sucking, leg bouncing, hair twirling and nail-biting. Simple motor stereotypies don’t typically interfere with your ability to function or cause significant distress.
• Complex motor stereotypies. These are more complex repetitive movements, like hand flapping, body rocking, and mouth and face movements. Complex motor stereotypies typically begin before age 3 and tend to persist throughout adolescence and adulthood. They often affect your ability to function and may cause bodily harm. SMD typically involves complex motor stereotypies.

Providers then classify each type of motor stereotypy as primary or secondary:

• Primary motor stereotypies happen without an underlying cause or neurodevelopmental disorder.
• Secondary motor stereotypies develop as part of a condition or neurodevelopmental disorder, like autism spectrum disorder (ASD) or a developmental delay.

In other words, if a child with ASD has motor stereotypies, providers view them as features of ASD (often called stimming), not stereotypic movement disorder. To be diagnosed with SMD, your child can’t have another diagnosis that explains the stereotypies.

How common is stereotypic movement disorder?

It’s difficult for researchers to say how common SMD is specifically, but it’s generally rare. They have more data on motor stereotypies.

Complex motor stereotypies are rare — studies show they affect 3% to 4% of children. But the rate of complex motor stereotypies is higher in children with certain diagnoses. They affect up to 61% of children with developmental disabilities and up to 88% of children with ASD.

Studies show that primary simple motor stereotypies occur in roughly 20% to 70% of typically developing children — they’re very common.

What are the symptoms of stereotypic movement disorder?

Stereotypic movement disorder involves motor (movement) stereotypies that affect your child’s ability to function or cause harm. Examples include:

• Hand flapping
• Body rocking
• Head banging
• Finger or arm wiggling
• Mouth and face movements (orofacial movements)
• Hitting, scratching or biting self
• Severe nail biting

These behaviors tend to happen more at times of:

• Increased stress
• Anxiety
• Excitement
• Focused concentration
• Boredom

Distraction typically reduces or stops the behaviors.

Children with SMD often say the movements feel pleasing or “right.” This is different from obsessive-compulsive behaviors, for example, in which you feel like you must do repetitive behaviors to get rid of obsessive thoughts. When someone tries to suppress or stop a child with SMD from doing the behaviors, the child often expresses frustration or irritation.

What causes stereotypic movement disorder?

Researchers don’t know the exact cause of stereotypic movement disorder. The repetitive movements aren’t associated with another neurological or neurodevelopmental diagnosis.

But in general, researchers think motor stereotypies develop due to an imbalance in certain brain chemicals (neurotransmitters), like dopamine, acetylcholine and GABA.

There also seems to be a genetic link with complex motor stereotypies. Children with complex motor stereotypies are more likely to have a first-degree relative (biological sibling or parent) with them. But researchers haven’t identified a specific gene that may be responsible for the movements.

How is stereotypic movement disorder diagnosed?

To get a diagnosis of stereotypic movement disorder (SMD), your child must meet all the following criteria:

• The repetitive movements exist for at least four weeks.
• The movements interfere with your child’s social, academic or other activities or cause self-injury.
• There’s no other medical explanation for the movements.

To start, your child’s healthcare provider will do a physical exam and ask you about your child’s medical history. They’ll ask about your child’s symptoms, like:

• When they started
• How often they happen
• If certain situations or environments trigger them
• How they affect your child’s daily functions

They’ll have to rule out other common causes of complex motor stereotypies, like autism spectrum disorder. This may involve various assessments and screenings.

Your child’s provider may also recommend some laboratory tests, like blood tests, to check if a physical condition is causing the movements.

What is the treatment for stereotypic movement disorder?

Stereotypic movement disorder doesn’t require treatment. But if your child wants help in reducing their movements — or the behaviors are causing self-injury — habit reversal training (HRT) can be effective. It can help reduce the severity and frequency of the movements.

HRT involves strategies like recognizing and identifying signs of when your child is about to start the movements and replacing them with other behaviors. Your child will use these strategies to self-manage the behaviors. In the classroom and at home, your child’s teacher and caregivers can also interrupt and redirect the behaviors.

If the motor stereotypies involve self-injury, like head banging or self-scratching, you may need to use interventions to protect your child. This could involve measures like having your child wear a helmet or having them wear gloves to reduce scratch injuries. Your child’s healthcare provider or an occupational therapist can help you come up with specific strategies unique to your child’s behaviors.

Studies show that medications may help manage complex motor stereotypies in children with autism and other neurodevelopmental diagnoses. But there aren’t studies that show these same medications can help with stereotypic movement disorder.

Can I prevent stereotypic movement disorder?

Researchers don’t know the cause of stereotypic movement disorder, so you can’t prevent it.

What can I expect if my child has stereotypic movement disorder?

The behaviors of SMD typically persist throughout adolescence and adulthood. As long as the movements aren’t causing self-injury, they’re not harmful. It may help to see your child’s behaviors simply as their way of interacting with the world. Sure, the behaviors may be different. But they’re not “wrong.”

If your child wants help with the movements, reach out to their healthcare provider or an occupational therapist. Giving your child a say in their own care can help them feel more in control of their body and have positive effects on their mental health.

What questions should I ask my child’s healthcare provider?

If your child has stereotypic movement disorder, it may help to ask their healthcare provider the following questions:

• What caused stereotypic movement disorder?
• How can we be sure that my child doesn’t have another diagnosis?
• Should I be looking for signs of other conditions?
• How can I help my child with stereotypic movement disorder?
• What specialists could help my child with stereotypic movement disorder?