Semantically-Triggered Reading Epilepsy: An Experimental Case Study

Abstract

Primary reading epilepsy (PRE) is a rare syndrome in which epileptic seizures are electively provoked by reading. Cognitive neuropsychology has demonstrated the existence of at least two pathways for reading, the sublexical pathway involved in converting graphemes to phonemes, and the lexical pathway used when meaning is conveyed. Which of these specific pathways is relevant in triggering epileptic discharges remains largely unknown. We report the case of a patient suffering from PRE in which the two routes were distinguished on the basis of the reading material employed. Significantly less epileptic discharges were observed when the patient read non-words than words. In view of our findings, we tentatively contrast a lexical form of PRE, triggered by the activation of semantic knowledge structures, with a sublexical form, triggered by non-word reading. Evidence from the literature suggests that the former is characterized by bilateral EEG activating patterns, whereas the latter involves preferentially the left hemisphere.