Delirium: a neurologist's view--the neurology of agitation and overactivity.

Delirium is a term used variously to characterize a change in behavior. Neurologists most often use the term to describe a patient who has acutely developed a hyperactive agitated state. In many patients, agitation and overactivity are explained by toxic and metabolic factors and infections. Lesions, especially strokes, in some brain regions have been reported to cause sudden agitation and a hyperactive state, often with an increased amount of speech output, the topics of which flit from one subject to another. Strokes and other lesions that involve the temporal lobes, fusiform and lingual gyri, caudate nucleus, and anterior cingulum have been reported to cause an acute hyperactive state similar to that found in patients with delirium tremens related to alcohol withdrawal.