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Imaging seizure activity: A combined EEG/EMG‐fMRI study in reading epilepsy
Author(s) -
SalekHaddadi Afraim,
Mayer Thomas,
Hamandi Khalid,
Symms Mark,
Josephs Oliver,
Fluegel Dominique,
Woermann Friedrich,
Richardson Mark P.,
Noppeney Uta,
Wolf Peter,
Koepp Matthias J.
Publication year - 2009
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1167.2008.01737.x
Subject(s) - epilepsy , reflex epilepsy , neuroscience , psychology , electroencephalography , functional magnetic resonance imaging , audiology , thalamus , supplementary motor area , medicine
Summary Purpose: To characterize the spatial relationship between activations related to language‐induced seizure activity, language processing, and motor control in patients with reading epilepsy. Methods: We recorded and simultaneously monitored several physiological parameters [voice‐recording, electromyography (EMG), electrocardiography (ECG), electroencephalography (EEG)] during blood oxygen level‐dependent (BOLD) functional magnetic resonance imaging (fMRI) in nine patients with reading epilepsy. Individually tailored language paradigms were used to induce and record habitual seizures inside the MRI scanner. Voxel‐based morphometry (VBM) was used for structural brain analysis. Reading‐induced seizures occurred in six out of nine patients. Results: One patient experienced abundant orofacial reflex myocloni during silent reading in association with bilateral frontal or generalized epileptiform discharges. In a further five patients, symptoms were only elicited while reading aloud with self‐indicated events. Consistent activation patterns in response to reading‐induced myoclonic seizures were observed within left motor and premotor areas in five of these six patients, in the left striatum (n = 4), in mesiotemporal/limbic areas (n = 4), in Brodmann area 47 (n = 3), and thalamus (n = 2). These BOLD activations were overlapping or adjacent to areas physiologically activated during language and facial motor tasks. No subtle structural abnormalities common to all patients were identified using VBM, but one patient had a left temporal ischemic lesion. Discussion: Based on the findings, we hypothesize that reflex seizures occur in reading epilepsy when a critical mass of neurons are activated through a provoking stimulus within corticoreticular and corticocortical circuitry subserving normal functions.