Psychosis and status epilepticus: Borderland or hidden cause?

Psychiatry, over the past century, has tended to echo the view of Hughlings-Jackson that ‘‘compound mental states cannot be owing to an epileptic discharge’’ (HughlingsJackson, 1958). The approach to investigating psychosis in patients with epilepsy has been to concentrate on the empirical use of descriptive psychopathology in order to delineate the various psychiatric syndromes and determine to what extent the various abnormalities of affect, thought (delusions), and perception (hallucinations) are similar to or differ from those seen in the ‘‘functional’’ psychoses in patients without epilepsy. An almost entirely separate ‘‘positivist’’ tradition has evolved within neurology. The central theorem of this school is that hallucinations occur as a consequence of the activation of a localized group of neurons, which can be investigated by cerebral recording and cerebral stimulation. The ‘‘gold standard’’ investigation has been intracranial stereoelectroencephalography (SEEG). Key differences between these two approaches lie in the definition of an hallucination and in the concept of a ‘‘compound mental state. ’’ David defines ‘‘hallucination’’ from the psychiatric perspective as ‘‘a sensory experience which occurs in the absence of corresponding external stimulation of the relevant sensory organ, has sufficient sense of reality to resemble a veridical perception, over which the subject does not feel s/he has direct and voluntary control, and which occurs in the awake state’’ (David, 2004); usually these may be auditory, but tactile and olfactory hallucinations are also seen in functional psychoses such as schizophrenia. The neurologic definition of a hallucination is undoubtedly broader; according to Denis Williams ‘‘an hallucination, which is a percept without a stimulus may be organic or psychotic.Local disturbance of the brain has evoked a perceptual response. (yet) there can be no fundamental difference between sensations felt in a limb or through the eye as a result of a local epileptic discharge. (crucially) the feelings called fear, depression or pleasure arising during the attack (also) have no local reference and for physiological purposes can be considered to be organic hallucinations’’ (Williams, 1959). In psychiatry the presence of hallucinations is usually taken to signify psychosis (i.e., complex mental states), yet although most psychiatrists would consider a patient experiencing complex auditory hallucinations or persecutory delusions to be ‘‘psychotic,’’ probably none would extend this term to include those experiencing ictal affects such as fear, rage, or depression. At the phenomenologic level the reduction of all these symptoms into the single category ‘‘hallucination’’ is both confusing and unhelpful. At the electrophysiologic level, however, distinction between many of these diverse psychopathologic categories is often not possible. It can be demonstrated that repeated seizures of a single area within the same patient can produce different psychic responses, whereas stimulation of widely distinct areas within the same individual can produce remarkable similar phenomena (Fish et al., 1993). Penfield noted that auras could be reproduced by electrical stimulation of the temporal lobe (Penfield, 1938). He was interested in the evocation of memory and distinguished between what he called experiential (mental events from the patients personal past) and interpretive phenomena (to do with the present circumstances of the patient). A key element of his later thinking was that experiential responses occur virtually only in seizures arising from the lateral temporal isocortex, where the stimulus was strong enough to provoke an afterdischarge (Penfield & Perot, 1963). The anatomic basis was revised further by Gloor, who imputed a key role for limbic structures rather than temporal neocortex (Gloor et al., 1982). He considered that the experiential phenomena were not the result of a loss of inhibitory control, as Hughlings-Jackson believed, but were the result of positive activation of limbic structures. In his matrix theory, he proposed that ‘‘an epileptic discharge within the temporal lobe at the onset of a seizure, Address correspondence to Dr. Brent Elliott, Department of Neuropsychiatry, The National Hospital for Neurology and Neuropsychiatry, Queen Square, London WC1N 3BG, U.K. E-mail: brent.elliott@ btinternet.com