epilepsy and hallucinations

   The term epilepsy comes from the Greek verb epilambanein (to attack). It refers to a neurological disorder characterized by recurrent seizures. The introduction of the term epilepsy is generally attributed to the Persian physician and philosopher Abu Ali Al-Hoessein Ibn Abdoel-lah Ibn Sina, better known as Avicenna (9801037). Among the more or less synonymous historic names are falling evil, great evil, Herculean disease, hieron nosema, morbus caducus, mor-bus lunaticus, morbus major sonticus, nosema paideon, sacred disease, and 'the disease called sacred'. The latter expression stems from the Hip-pocratic Corpus, where it was used to express the authors' suspicion of a natural rather than a metaphysical affliction. Nevertheless, epilepsy retained its metaphysical connotations until the 18th century and beyond. Today the seizures characteristic of epilepsy are attributed to abnormal, excessive, and/or synchronous neuronal discharges in the brain. Over the years, the International League Against Epilepsy (ILAE) has issued several classifications of epilepsy, designed to facilitate clinical diagnosis and empirical research. The members of this classification constitute epileptic syndromes, i.e. hypothetical noso-logical constructs involving neurological diseases that can be held responsible for the mediation of certain types of seizure. The ILAE has also issued several classifications of epileptic seizures. An arrangement of epileptic seizures according to the sensory spheres or modalities in which they may manifest themselves yields the following classification: motor seizures (affecting the motor sphere), dialeptic seizures (affecting the consciousness sphere), special seizures (affecting the autonomic sphere), and " aurae (affecting the sensory sphere). Hallucinations, "illusions, and " sensory distortions occurring prior to an epileptic seizure tend to be relegated to the aura category. However, these perceptual phenomena also occur during the aftermath of a seizure. In the international literature, both types of epilepsy-related hallucinatory phenomena are also referred to as experiential phenomenon, experiential hallucinosis, experiential response, ictal hallucination, epileptic hallucination, and hallucinatory epilepsy. A third category of hallucinatory phenomena attributed to epilepsy are those occurring in the context of a "twilight state. A relation between epilepsy and hallucinations has been suspected for at least 2,000 years. In 1889 the British neurologists John Hughlings Jackson (1835-1911) and Charles Beevor (18541908) were the first to describe an " olfactory aura occurring in the context of an epileptic seizure, with a demonstrable tumour in the patient's right temporal lobe. Jackson went on to study aurae, developing his nosological models of the "dreamy state and uncinate epilepsy. Since the time of Jackson and Beevor, aurae have been described for each of the sensory modalities. When occurring exclusively in the context of epilepsy, such aurae are referred to as aura epileptica. These phenomena typically last for several seconds, sometimes minutes. With the aid of cortical probing experiments it has been demonstrated that aurae can also be evoked artificially. In accordance with the sensory modality involved, the ILAE classifies aurae as "somatosensory aura, "visual aura, " auditory aura, "olfactory aura, " gustatory aura, " autonomic aura, " abdominal aura, and " psychic aura. The latter class is reserved for hallucinations or illusions of epileptic origin that are not confined to a single sensory modality. Such "compound hallucinations maybe accompaniedby"metamorphopsias (such as " micropsia or " macropsia), and/or an alteration in the sense of familiarity (such as dereal-ization, "déjà vu,or * jamais vu). In rare instances, they may develop into a full-blown "Alice in Wonderland syndrome. Aurae taking the shape of " complex visual hallucinations are less common and tend to be briefer than stereotyped ones. As to their pathophysiology, it has been suggested that " stereotyped hallucinations are associated primarily with aberrant neuronal discharges affecting the sensory cortex, whereas complex ones may be associated with discharges affecting the limbic structures.

   References

   Jackson, J.H., Beevor, C.E. (1889). On a case of epileptic attacks with an olfactory aura from a tumour in the right temporosphenoidal lobe. Lancet, 1, 381.

   Karbowski, K., ed. (1982). Halluzinationen bei Epilepsien und ihre Differentialdiagnose.Bern: Verlag Hans Huber.

   Lüders, H., Acharya, J., Baumgartner, C., Ban-badis, 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.

   Mauguière, F. (1999). Scope and presumed mechanisms of hallucinations in partial epileptic seizures. Epileptic Disorders, 1, 81-91.

   Ohman, R., Vogel, A., eds. (1984). Temporal lobe epilepsy, psychotic and neurological manifestations, clinical tradition and new vistas. Proceedings ofa symposium held in Copenhagen, 10-11 November 1982. Acta Psychiatrica Scan-dinavica supplementum no. 313, Vol. 69. Copenhagen: Munksgaard.

   Pryse-Phillips, W. (2003). Companion to clinical neurology. Second edition. Oxford: Oxford University Press.

   Sowa, M.V., Pituck, S. (1989). Prolonged spontaneous complex visual hallucinations and illusions as ictal phenomena. Epilepsia, 30, 524-526.

   Taylor, I., Scheffer, I.E., Berkovic, S.F. (2003). Occipital epilepsies: Identification of specific and newly recognized syndromes. Brain, 126, 753-769.