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Mental imagery of photic stimulation provokes paroxysmal EEG activity in a photosensitive patient who self-induces seizures

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Abstract

This article reports a case of a 14 year-old male photosensitive epileptic patient who was able to induce fits subjectively by the mental imagery of the effective visual stimuli. The patient underwent a comprehensive electroencephalographic (EEG) examination including hyperventilation. The basic EEG showed abnormalities. Intermittent photic (IPS) and pattern stimulations (PtnS), evoked photo and pattern paroxysmal responses (PPRs) within a wide range of frequencies from 2–50 flashes per second (fps) and 0.5–6 cycles per degree (cdp) respectively. The patient was able to reconstruct the PPRs mentally on exposure to the effective stimuli of 25 and 50 fps, and 2.0 and 3.25 cpd respectively. His cognitive functions were not affected when exposed to photostimulation. However, on exposure to pattern stimulation, he became totally confused and his consciousness was impaired. These findings showed that self-induction of fits in photosensitive epilepsy is a mental phenomenon which takes place with or without loss of cognitive function depending on the rate and frequency of the physical and the ‘imagined’ stimuli.

Sommario

Viene riportato il caso di un paziente maschio di 14 anni, affetto da epilessia fotosensibile, che era in grado di autoindursi le crisi attraverso la rappresentazione mentale dello stimolo visivo. Lo studio elettroencefalografico (EEG) evidenziava anomalie epilettiformi intercritiche e una risposta fotoparossistica (fps: a stimoli con flashes compresi tra 2 e 50 Hz), era inoltre presente una risposta a pattern di stimolazione a griglia (PPRs: con frequenze spaziali comprese tra 0.5 e 6 cicli per grado). Le funzioni cognitive non erano alterate durante fps mentre si osservava compromissione dalla coscienza durante PPRs. Effetti analoghi erano determinati dalla ricostruzione mentale della stimolazione con flashes (25–50 Hz) e con patterns (2–3.25 cicli per grado). I risultati dimostrano che l'autoinduzione di crisi nell'epilessia fotosensibile è dipendente dalla capacità di ricostruire mentalmente le caratteristiche fisiche dello stimolo visivo efficace.

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Authors and Affiliations

  1. Formerly of Aston University Clinical Neurophysiology Unit, Birmingham, UK

    Anyanwu E. MSc (AIMLS, FRSH)

  2. Flat 10 Old College House, 188 College Road, Saltley, B8 3TQ, Birmingham, U.K.

    Anyanwu E. MSc (AIMLS, FRSH)

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  1. Anyanwu E. MSc
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Anyanwu, E. Mental imagery of photic stimulation provokes paroxysmal EEG activity in a photosensitive patient who self-induces seizures. Ital J Neuro Sci 18, 93–100 (1997). https://doi.org/10.1007/BF01999569

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  • DOI: https://doi.org/10.1007/BF01999569

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