Motoric subtypes of delirium.

Delirium is a common neuropsychiatric disorder with wide ranging symptoms and significant morbid impact. Disturbances of motor behavior are an important feature of delirium and form the basis for the most commonly studied clinical subtype. This article reviews the relevance of motoric disturbance to delirium phenomenology and discusses possible neurobiological causes for different presentations of motor behavior in delirium. Evidence is presented to support the usefulness of using motorically defined subtypes based on identified differences according to underlying origins, pathophysiologies, responsiveness to therapy and natural course. Methodological issues relating to motoric subtype studies are addressed and suggestions for future research are made.