- Also known as acute confusional state, acute organic reaction, acute brain syndrome, confuso-oneiric state, and toxic-metabolic encephalopathy. The term delirium comes from the Latin verb delirare, which means to go off the furrow, to derail. The term was used in the Hippocratic Corpus and other ancient medical texts with a variety of connotations, mostly revolving around the notion of a disturbance in the train of thinking. The various contexts in which the term was used are often epistemologically discontinuous with current medical thinking. During the first part of the 19th century (and especially in the French medical literature) the term delirium (délire)was used for a variety of mental states, including those characterized by disorders of intellectual function, errors of judgment (i.e. delusions), and perceptual disturbances (such as hallucinations). For a long time, delirium was distinguished from mental illness by the presence of fever. It was the French alienist Alexandre Jacques François Brierre de Boismont (1797-1881) who in 1845 made an important contribution to the syndro-matic approach which is in use today by suggesting that delirium should be conceptualized as an acute, prototypical type of insanity. Today thetermdeliriumisusedtodenoteahetero-geneous mental and neurobehavioural syndrome which is by definition associated with organic disease, although not necessarily with fever. As to its symptomatology, delirium is characterized primarily by alterations in the level of consciousness (i.e. 'clouding'), and by a disorientation in time and space. Additional symptoms may include attention deficits, impairments of cognitive functioning, delusions, hallucinations, " illusions, speech disorders, an altered sleep-wake cycle, and behavioural symptoms such as restlessness, agitation, disrobing, plucking, physical aggression, and wandering. The hallucinations and illusions occurring in the context of delirium are primarily of a "visual nature, although the other sensory modalities may be involved as well. "Zoopsia and "formicative hallucinations are considered classical symptoms. The term " delirium tremens is reserved for delirious states occurring in the context ofalcohol withdrawal.ReferencesEsquirol, J.-E.D. (1965). Mental maladies. A treatise on insanity. A facsimile of the English edition of 1845. Translated by Hunt, E.K. New York, NY: Hafner Publishing Company.Kandinsky, V. (1885). Kritische und klinische Betrachtungen im Gebiete der Sinnestäuschungen. Erste und zweite Studie. Berlin: Verlag von Friedländer und Sohn.
Dictionary of Hallucinations. J.D. Blom. 2010.