Stereotypic movement disorder

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. While stereotypic movements are common in infancy and early childhood, a diagnosis of SMD is made only when such behaviors are prolonged, intense, and cause significant impairment. The diagnosis requires that the behavior in question must not be due to the direct effects of a substance, autism, or another medical condition.

The cause of this disorder is not known. However, current research suggests that dysfunction in corticostriatal-thalamo-cortical (CSTC) circuits and imbalances between the direct and indirect pathways of the basal ganglia may play a role in its development. Both environmental and genetic factors have been proposed as potential risk factors. Environmental factors include limited social interaction, neglect, and psychological stress, while a genetic predisposition is suspected, although no specific gene has been identified.

There are no definitive treatments for SMD. However, behavioral interventions, particularly habit reversal training, have shown promise in reducing symptoms. Pharmacological treatments such as clonazepam and naltrexone have also been identified as potential treatments, but findings remain inconclusive.