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


CONCLUSIONS
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.
Salek-Haddadi
Afraim
A
Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, Queen Square, London, United Kingdom.
Mayer
Thomas
T
Hamandi
Khalid
K
Symms
Mark
M
Josephs
Oliver
O
Fluegel
Dominique
D
Woermann
Friedrich
F
Richardson
Mark P
MP
Noppeney
Uta
U
Wolf
Peter
P
Koepp
Matthias J
MJ
D000328:Adult; D001921:Brain / Q000503:physiopathology; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology; D004562:Electrocardiography; D004569:Electroencephalography; D004576:Electromyography; D020195:Epilepsy, Reflex / Q000175:diagnosis / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology; D005152:Facial Muscles / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009415:Nerve Net / Q000503:physiopathology; D009474:Neurons / Q000502:physiology; D010100:Oxygen / Q000097:blood*; D012660:Semantics; D012815:Signal Processing, Computer-Assisted; D014705:Verbal Behavior / Q000502:physiology; D055815:Young Adult
D010100:Oxygen