- 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 one's own physical body, or a loss of the sensation of physical existence. The German neurologist and neurosurgeon Otfrid Foerster (1873-1941) 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 acoen-esthesiopathy 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, hemidepersonaliza-tion, 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 aso-matognosia/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. Pathophysio-logically, 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 Cotard's 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 Cotard's syndrome or even by * negative autoscopy (i.e. the failure to visually perceive one's own body).ReferencesFoerster, O. (1903). Ein Fall von elementarer allgemeiner Somatopsychose. (Afunktion der Somatopsyche.) Ein Beitrag zur Frage der Bedeutung der Somatopsyche für das Wahrne-mungsvermögen. Monatsschrift für Psychiatrie und Neurologie, 14, 189-205.Deny, G., Camus, P. (1905). Sur une forme d'hypochondrie aberrante due à la perte de la conscience du corps. Revue Neurologique,9, 461-167.Deny, G., Camus, P. (1905). Sur un cas de délire métabolique de la personnalité lié à des troubles de la cœnesthésie. Archives de Neurologie, 20, 257-268.Sacks, O. (1992). Migraine. Revised and expanded. New York, NY: Vintage Books.Arzy, S., Overney, L.S., Landis, Th., Blanke, O. (2006). Neural mechanisms of embodiment: Asomatognosia due to premotor cortex damage. Archives of Neurology, 63, 1022-1025.
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