Blom - A Dictionary of Hallucinations

Parnassia Bavo Group & University of Groningen, Paradijsappelstraat 2, 2552 HX The Hague, The Netherlands

Also known as visceral aura and epigastric aura. The term abdominal aura is indebted to the Latin words abdomen (belly) and aura (wind, smell). It is used to denote a type of *somatosensory or *somaesthetic aura that typically manifests itself as a rising epigastric sensation. Other presentations of the abdominal aura include viscerosensitive sensations such as abdominal discomfort, visceromotor symptoms presenting in the form of tachycardia, borborygmi or vomiting, and vegetative symptoms such as blushing and sweating. Pathophysiologically, the abdominal aura is associated with aberrant neuronal discharges in sensory cortical areas representing the abdominal viscera. Etiologically, it is associated primarily with paroxysmal neurological disorders such as migraine and epilepsy. The abdominal aura can be classified as a *somatic or *coenesthetic hallucination. The term is used in opposition to various terms denoting other types of somatosensory aura, notably *splitting of the body image and *paraesthesia.

The term absinthism is indebted to the French noun absinthe , which in turn derives from the Greek noun apsinthion (wormwood). It has various connotations, referring either to the habitual ingestion of absinth or to a group of symptoms associated with absinth intoxication and/or withdrawal. This group of symptoms includes hallucinations and other *psychotic phenomena, *amaurosis fugax, insomnia, vertigo, tremors, transient paralysis of the limbs, *delirium, and epileptic seizures. Absinth is an emerald-green liqueur flavoured with extracts of green anise, florence fennel, and grande wormwood (sometimes referred to as the holy trinity), as well as a mix of other herbs. It was created around 1792 as an all-purpose patent remedy by the French physician Pierre Ordinaire (17411821). The drink, which was marketed by the Swiss distiller Henri-Louis Pernod (17761851), became extremely popular in 19th-century Europe and, to a lesser extent, in the United States. Among those who contributed to the almost mythical proportions of absinths reputation were Charles Baudelaire (18211867), Edouard Manet (18321883), Edgar Degas (18341917), Vincent van Gogh (18531890), Oscar Wilde (18541900), and Henri de Toulouse-Lautrec (18641901). The mechanism of action of absinth in the mediation of hallucinations is unknown. The person credited with conducting the first experimental biomedical research on the drinks hallucinatory effects is the French alienist Jacques Joseph-Valentin Magnan (18351916). Magnan exposed various mammals to the vapours of either wormwood oil (the essence of absinth) or alcohol (the base of absinth). As he reported in 1874, the animals that inhaled the alcohol vapours got drunk, while those that inhaled the vapours of wormwood had a heightened risk of epileptic seizures. On the basis of observations such as Magnans, it has been suggested that thujone (one of the active components of wormwood oil) acts as a convulsant and is thus responsible for mediating the notorious hallucinatory activity of absinth intoxication. However, it has also been suggested that the absolute amounts of thujone in absinth are so small that its effects are overshadowed by those of ethanol, and that the latter ingredient should therefore be held responsible for the majority of symptoms associated with absinthism. In the latter reading, the hallucinations are attributed either to ordinary *alcoholic hallucinosis or to the effects of alcohol withdrawal delirium. A third hypothesis suggests that the hallucinatory effects reported in the 19th century did differ from alcoholic hallucinosis and withdrawal delirium, but only because they were due to cheap imitations of absinth that contained copper sulphate and other toxins instead of chlorophyll from plant extracts to mimic the drinks characteristic emerald-green colour. Some of the other candidate substances for the purported hallucinogenic effects of those imitations are methanol, *nutmeg, calamus, turmeric, and aniline green. The 19th-century European and American authorities considered absinth such a severe threat to public health that around 1900 it was legally prohibited in many Western countries. For over a century, that ban remained largely in place. During the early 21st century many of those countries legalized the consumption of absinth, thus far without any notable effects upon public health.

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Also known as acoenesthesiopathy, general elementary somatopsychosis, and asomatognosia. The term acenesthesia comes from the Greek words a (not), koinos (communal), and aisthanesthai (to notice, to perceive). It translates loosely as not being able to perceive the common sensation. In this context the expression common sensation refers to the classic medical concept of coenesthesis, which refers to the common sensation or common general sensibility arising from the sum of all bodily sense impressions. (For a further explanation of the term coenesthesis, see the entry Coenesthetic hallucination.) The terms acenesthesia and acoenesthesiopathy are used to denote a rare condition characterized by a total lack of awareness of ones own physical body, or a loss of the sensation of physical existence. The German neurologist and neurosurgeon Otfrid Foerster (18731941) is commonly credited with providing the first case report of a person suffering from acenesthesia in a paper published in 1903. Foerster himself used the German expression allgemeine elementare Somatopsychose (i.e., general elementary somatopsychosis) to denote this condition. The individual described in this paper complained that she could no longer feel her head, her arms, her legs, or any of her other body parts, unless they were touched by someone or something. In his paper Foerster attributes this disorder of coenesthesia to a lack of function of the somatopsyche and points out that it would seem to have a chronic course. In 1905 the term acoenesthesiopathy was attached to this condition by the French neurologists Paul Camus and Gaston Deny. Camus and Deny envisage acoenesthesiopathy as a disorder of coenesthesia. As a generic term for this group of disorders they propose the term *coenesthesiopathy. Unilateral feelings of nothingness are referred to in the literature as *hemiasomatognosia, imperception for one-half of the body, hemidepersonalization, negative phantoms, autosomatamnesia, and autosomatagnosia. It is as yet uncertain whether acenesthesia deserves to be classified as a distinct nosological entity or rather as a symptom occurring in the context of disorders such as *dissociation and migraine. In the context of migraine, it is known as a complication of the equally rare bilateral spectrum. Today the term acenesthesia has been largely discarded in favour of asomatognosia, a term attributed to the French psychiatrist Jean Lhermitte (18771959). Moreover, modern descriptions of asomatognosia/acenesthesia tend to include cases in which the lack of awareness of bodily feelings is restricted to one or more body parts, such as an arm, a leg, both arms, or both legs. Pathophysiologically, acenesthesia is associated primarily with lesions affecting one or more parts of the parietal cortex involved in embodiment and corporeal awareness (more specifically, the premotor cortex). In the literature on asomatognosia right-sided parietal lesions would seem to dominate, affecting the contralesional side of the body. Acenesthesia should not be confused with *total anaesthesia, which is characterized by a failure to detect tactile and other somatosensory stimuli, or with Cotards syndrome, a condition in which the affected individual may have the delusional conviction as opposed to the perceptual experience that his or her body has ceased to exist. However, it may be accompanied by Cotards syndrome or even by *negative autoscopy (i.e. the failure to visually perceive ones own body).