- Also known as allachesthesia, allesthesia, allaesthesia, allochaesthesia, allochesthesia, alloesthesia, and atopognosis. The term allachaesthesia comes from the Greek words allache (elsewhere) and aisthanesthai (to notice, to perceive). It translates loosely as 'perception in a different place' and refers to a mislocation of tactile sensations to a location other than the one that is actually being touched. The term allachaesthesia was introduced in or shortly before 1894 by the British neurologist Thomas Grainger Stewart (1877—1957) to denote horizontal or diagonal displacements of localization for touch confined to the ipsilat-eral side of the body. Stewart noted that this phenomenon bore a resemblance to *allochiria (i.e. a condition characterized by a mislocation of sensory stimuli to the corresponding opposite half of the body). Today allochiria is generally considered a variant or subset of the class allachaesthesia. Two variants of allachaesthesia that occur in other sensory modalities are gustatory allachaesthesia and * visual allachaesthesia. Another condition phenomenologically related to allachaesthesia is * spinal cord damage-induced synaesthesia. It is unlikely, however, that the two phenomena are related in a pathophysiological sense as well. A condition in which unilateral stimulation produces bilateral tactile sensations is called * synchiria.ReferencesStewart, T.G. (1894). A clinical lecture on a case of perverted localisation of sensation or allachaesthesia. British Medical Journal,1, 1—4.Meador, K.J., Allen, M.E., Adams, R.J., Loring, D.W. (1991). Allochiria vs allesthesia. Is there a misperception? Archives of Neurology, 48, 546—549.
Dictionary of Hallucinations. J.D. Blom. 2010.