aura

   Also known as aural phenomenon and psychical state. The term aura is Greek for wind, breeze, or smell. Its introduction into medicine has been attributed to the Greek physician Pelops, the master of the great Galen of Pergamum (129-c. 216 AD). Reportedly, Pelops used the term to denote the phenomena he had often observed preceding attacks of epilepsy (referred to as "the disease called sacred" throughout the Hippocratic Corpus). Being struck by 'marches' of involuntary motor movements starting in the foot or hand, and apparently ascending up to the head, Pelops conceptualized the aura as a "cold vapour" affecting the limbs and passing up through the peripheral blood vessels - which the Greeks believed to be filled with air - towards the head. Aurae were studied extensively during the 19th century, notably by the British neurologist John Hughlings Jackson (1835-1911). By then they were no longer conceptualized as being mediated by vapours nor were the blood vessels conceptualized as containing air. But the notion of a peripheral origin of the aura remained largely in place. Jackson's concept of uncinate epilepsy as the pathophysiological basis of aurae reversed the notion of their peripheral origin. Today the terms aura and aura epileptica are used to denote an ictal manifestation of an epileptic seizure that manifests itself in the form of a sensory (i.e. hallucinatory), psychosensory, and/or experiential symptom. The hallucinatory symptoms are also referred to as ictal hallucinations. An aura may occur either in isolation or as a 'warning symptom' preceding a paroxysmal neurological event such as an epileptic seizure or a migraine attack. As the German psychiatrist and philosopher Karl Jaspers (1883-1969) wrote, "During [an aura] the outer world disappears; the inner experiences become overpowering, consciousness narrows and in this restricted state it can yet have a moment of high illumination." Aurae typically last for seconds, or at most minutes. In his writings on uncinate epilepsy, Jackson focused primarily on aurae mediated by the temporo-sphenoidal lobe. It is now known, however, that they can be mediated by the parietal and occipital lobes as well and that they can manifest themselves in any of the sensory modalities. In accordance with the sensory modality involved, they were classified in 1998 by the International League Against Epilepsy (ILAE) as *somatosensory aura, *visual aura, *auditory aura, *olfactory aura, *gustatory aura, *autonomic aura, *abdominal aura, and * psychic aura. A rare type ofaura that can persist for months or even years without any signs of cerebral infarction is referred to as *persistent aura without infarction. Historical personages who described their own experience ofwhat have been retrospectively identified as aurae include Charles Lutwidge Dodgson (better known as Lewis Carroll, 1832-1898), Hildegard of Bingen (1098-1179), and Fyodor Mikhailovich Dosto-evsky (1821-1881). Today the term aura is also used by the ILAE as the name of a major category of epileptic seizures, namely those affecting the sensory sphere (see the entry Epilepsy and hallucinations). In parapsychology, the term aura is used somewhat differently, denoting a * visual halo of subtle, multicoloured, and luminous radiations said to surround human beings and other living creatures.

   References

   Gowers, W.R. (1885). Epilepsy. London: Churchill.

   Jaspers, K. (1997). General psychopathology. Volume 1. Translated by Hoenig, J., Hamilton, M.W. Baltimore, MA: Johns Hopkins University Press.

   Lüders, H., Acharya, J., Baumgartner, C., Banbadis, S., Bleasel, A., Burgess, R., Dinner, D.S., Ebner, A., Foldvary, N., Geller, E., Hamer, H., Holthausen, H., Kotagal, P., Morris, H., Meencke, H.J., Noachtar, S., Rosenow, F., Sakamotot, A., Steinhoff, B.J., Tuxhorn, I., Wyllie, E. (1998). Semiological seizure classification. Epilepsia, 39, 1006-1013.

   Bien, C.G., Benninger, F.O., Urbach, H., Schramm, J., Kurthen, M., Elger, C.E. (2000).

   Localizing value of epileptic visual auras. Brain, 123, 244-253. Wilkinson, F. (2004). Auras and other hallucinations: Windows on the visual brain. Progressin Brain Research, 144, 305-320.