Hallucinations in Psychoses and Affective Disorders by Paolo Brambilla & Massimo Carlo Mauri & Alfredo Carlo Altamura

Author:Paolo Brambilla & Massimo Carlo Mauri & Alfredo Carlo Altamura
Language: eng
Format: epub
ISBN: 9783319751245
Publisher: Springer International Publishing

7.5 Epilepsy

Epilepsy is a group of neurological disorders characterized by epileptic seizures [46]. During a seizure, an abnormal, excessive, hypersynchronous discharge of a group of cortical neurons can lead to hallucinations or illusions. These phenomena, when they forego an impairment of consciousness and/or a generalized seizure, are called epileptic auras. They can manifest in a fully awake state, but can also be associated with various degrees of disturbed consciousness and various other seizure manifestations, such as motor activity and automatisms.

The modalities of the symptoms can provide localizing information. For example, when epileptic focus is located in a brain region involved in sensory integration, the seizure discharge can give rise to auditory, gustatory, olfactory, somatic, and visual false sensations. More rarely, in addition to these elementary sensory perceptions, hallucinations can be more complex (e.g., perceptions of visuospatial scenes or hearing elaborated music). By involving emotional circuits of the brain, the seizures can lead to hallucinatory emotional states (e.g., fear or joy), illusions (e.g., déjà vu or déjà vécu), or delusional beliefs (e.g., identity change or bizarre religious experiences). Auditory hallucinations have a specific localization of epileptic focus near Heschl’s gyrus and the auditory association areas [47]. Olfactory hallucinations are relatively infrequent in epilepsy and are a manifestation of temporal lobe epilepsy [48]. Gustatory hallucinations are also considered rare in epilepsy. Isolated brief gustatory hallucinations could be elicited from stimulation of the right Rolandic operculum, parietal operculum, amygdala, hippocampus, medial temporal gyrus, and anterior part of the right temporal gyrus [49]. Somatic hallucinations (e.g., abdominal and epigastric sensations) are associated with electric activity in the postcentral gyrus, parietal operculum, insula, and inferior parietal lobule [50]. Visual hallucinations, elementary and complex, and visual illusions are common in occipital seizures. Epileptic visual hallucinations are usually elementary, brief, stereotyped, and fragmentary. They can be divided into positive (flashes of color, bright-colored spots, phosphenes) and, more rarely, negative manifestations (amaurosis, scotoma). Elementary hallucinations usually last between 5 and 30 s. Their onset is usually monolateral, appearing in the temporal visual hemifield and then moving horizontally to the contralateral side [51]. If the hallucinatory images are restricted to one visual field, they have lateralizing value to the contralateral occipital cortex. Illusions, on the other hand, may appear as objects changing in size (macropsia and micropsia) and shape (metamorphopsia), or losing color (achromatopsia) [52]. Involvement of the posterior parietal and temporal association cortex renders the hallucinations more complex and colorful [53, 54]. Complex visual hallucinations tend to last from a few seconds to minutes, with the patient retaining insight into the unreality of the experience [52]. They may be more prolonged as a form of nonconvulsive status epilepticus and if occurring during sleep they can be interpreted as dreams. Palinopsia is a peculiar type of epileptic manifestation in which images persist or duplicate; in this case, the epileptic focus has been localized to the right posterior cerebral region. Another interesting phenomenon is autoscopy, in which subjects perceive mirror images of themselves of normal size, shape, and density in situations from their past or performing complex tasks.

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