stereotypic movement disorder
in DSM–IV–TR and DSM–5, a disorder characterized by repetitive, nonfunctional, and often self-injurious behaviors, such as head banging, biting or hitting parts of the body, rocking, or hand waving. It may be associated with intellectual disability and can arise at any age, though typically its onset begins in early childhood. Stereotypic movement disorder is distinguished from other disorders marked by repetitive or persistent movements, such as tic disorders, trichotillomania, and obsessive-compulsive disorder; by stereotyped movements that may occur without self-injury in a neurodevelopmental disorder such as autistic spectrum disorder; or by involuntary movements resulting from the effects of a medication or other substance (as in tardive dyskinesia) or from another medical condition such as Huntington’s disease.