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Imaging seizure activity: a combined EEG/EMG-fMRI study in reading epilepsy

Afraim Salek-Haddadi, Thomas Mayer, Khalid Hamandi, Mark Symms, Oliver Josephs, Dominique Flügel, Friedrich Woermann, Mark P Richardson, Uta Noppeney, Peter Wolf & Matthias J Koepp

abstract

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.
   
citation Salek-Haddadi A, Mayer T, Hamandi K, Symms M, Josephs O, Flügel D, Woermann F, Richardson M P, Noppeney U, Wolf P, Koepp M J. Imaging seizure activity: a combined EEG/EMG-fMRI study in reading epilepsy. Epilepsia 2008; 50:256-64.
   
type journal paper/review (English)
date of publishing 19-08-2008
journal title Epilepsia (50/2)
ISSN electronic 1528-1167
pages 256-64
PubMed 18717713
DOI 10.1111/j.1528-1167.2008.01737.x