Cerebral Activity Related to Primary Motor Stereotypies in Children: An EEG Study.

Background: * Motor stereotypies are a movement disorder characterized by involuntary, repetitive, and rhythmic movements. These movements have a predictable pattern and seem purposeful, but they serve no obvious function, tend to be prolonged, and can be suppressed. Common examples of motor stereotypies include hand waving, head nodding, and body rocking. * Researchers are interested in learning more about motor stereotypies. Many children with autism and other developmental disorders tend to exhibit these behaviors, but normal healthy children and even some adults have demonstrated motor stereotypies under certain conditions (including boredom and stress). More research is needed to determine the internal causes of and potential successful treatments for these behaviors. Objectives: \- To use electroencephalography (EEG) to study cerebral activity related to stereotypies in children. Eligibility: \- Children between 7 and 18 years of age who demonstrate stereotypy movements on a consistent basis (at least 10 times a day for at least 4 months). Design: * The study will require two visits to the National Institutes of Health Clinical Center. * First visit: Outpatient screening visit to determine the child s eligibility for the study, including questionnaires for parents/guardians and a medical assessment of the stereotypies. * Second visit: Participating children will spend 1 day in a room at the NIH Clinical Center Pediatric Day Hospital. During the visit, participants will wear a portable EEG unit to measure brain activity. For the first hour of the visit, researchers will perform movement tests to study the brain activity related to normal movements. For the rest of the day, participants may play games, watch television or movies, read, or nap, while continuing to wear the EEG to monitor brain activity related to the stereotypic movements. * Participants will receive a small amount of compensation for their time and participation.