Stereotypic Movement Disorder

What is Stereotypic Movement Disorder (SMD)

Stereotypic Movement Disorder (SMD) involves frequent repetitive, sometimes rhythmic, but purposeless movements. The repetitive movements may lead to self-injury or bodily harm. Symptoms usually appear within the first 3 years of life and consistently impact normal daily functioning. SMD is usually diagnosed in children with intellectual or developmental disabilities. It is more common in boys than in girls but can impact both genders. Sometimes SMD is misdiagnosed as tics or obsessive-compulsive disorder (OCD).

Often, children with intellectual disabilities or developmental disabilities, such as autism, are diagnosed with SMD. However, not all people who are diagnosed with SMD have intellectual or developmental disabilities. Some people who are diagnosed with SMD have other neurological conditions or have had a brain injury. However, for some normal developing children diagnosed with SMD, the cause remains unknown. 

Stereotypies are defined as repetitive movements or sounds and can include simple or more complex movements. Common stereotypic movements that constitute a diagnosis of SMD include hand flapping or waving, finger tapping, body rocking, pacing, head banging, and self-biting. The movements cause significant distress and impact normal daily functioning. SMD symptoms may lesson with treatment and medication.

Signs and Symptoms

There are several symptoms common to SMD. Symptoms include:

  • Body rocking
  • Hand flapping or hand waving
  • Head banging
  • Self-hitting
  • Self-biting
  • Nail biting
  • Skin picking
  • Mouthing or biting of objects

Symptoms present differently for each individual, often with a signature or primary repetitive movement. Sometimes the movements can be stress, excitement, or boredom induced. Symptoms may be classified as mild, moderate, or severe. Depending on the severity of the symptoms, treatment may include behavior modification or protective measures, or both.


The cause of SMD in normal developing children remains unknown. Ongoing research suggests that there may be a genetic link, but more research is needed. Research has also theorized that the stereotypies can be a function of too much or too little sensory stimulation. 

Children may experience the movements as a way to self-soothe when stressed or overstimulated, or there’s an inability to escape the overwhelming external or internal stimuli. The movements can help alleviate anxiety and stress, which then creates a positive reinforcement for the repetitive movements. Alternatively, children may also exhibit stereotypies when bored or under-stimulated.

Additionally, stereotypic movements can also occur due to drug use, certain medications, brain injuries, or other neurological conditions.


Treatment options for SMD consist of psychotherapy that includes behavioral modification techniques, and much less frequently, medication may be prescribed. Therapy seeks to reduce the repetitive movements to a more manageable level, allowing the child to function at a more normal level in daily life. In more extreme cases, behavior modification and protective measures (such as wearing a helmet) are used when self-injury may occur. Specific behavior therapies that are used include:

  • Differential reinforcement of other behaviors (DRO). This is a behavioral therapy that rewards socially appropriate behavior, thus creating positive reinforcement, which helps to reduce stereotypies.
  • Functional communication training (FCT). This therapy helps children learn to identify stress triggers and body cues and helps to develop alternative ways of responding to the stress instead of using repetitive movements to cope. Alternative responses and verbal strategies are rewarded.
  • Relaxation techniques. Mindfulness and body-based exercises help children learn how to regulate their nervous system and keep their body feeling calm and relaxed. Being in a relaxed and calm body lessens the impulse for stereotypic movements.

Research has shown inconsistent results regarding the effectiveness of medication intervention, and it is not prescribed often as a treatment for SMD. Exceptions may include recommending medication for children with autism or severe developmental or intellectual disabilities who have stereotypies. Additionally, if drug use is the cause of stereotypies, they usually clear up after cessation of the drug.

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