Complex Motor Stereotypies: An Evolving Neurobiological Concept

Abstract

Complex motor stereotypies are repetitive arm and/or hand flapping, waving and wiggling movements that begin before the age of 3 years, occur repeatedly throughout the day and stop with distraction. These movements are commonly seen in children with autism, but also appear in otherwise normally developing individuals labelled as primary. Although proposed to have a psychological and neurobiological mechanism, evidence suggests that there is an abnormality within the corticostriatal–thalamocortical circuitry or its connecting structures. Animal models include both drug-induced (i.e., via stimulants or cocaine) and spontaneously appearing prototypes. Neurochemical investigations, primarily in rodents, have identified a variety of neurotransmitter alterations, with an emphasis on dopamine or glutamate; however, findings are inconsistent. We hypothesize that, based on its various roles in controlling and modulating movements, the frontal cortex will ultimately be shown to be the prime site of abnormality in this disorder. Future studies investigating both humans and animal models are essential for attaining a greater understanding of the pathobiology underlying motor stereotypies.