Abstract Details

Title A Novel Method To Map Interictal Epileptiform Discharges from Simultaneous EEG-fMRI Data

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S28 - (-)

Poster/Presentation
Number 002

Objective

Background Studies of functional connectivity have shown that spontaneous fMRI signals are robustly correlated across the brain, and the spatial pattern of correlation is generally invariant across time. We hypothesize that during IED events, regions with IEDs have significantly different patterns of fMRI signal correlation compared to baseline (no IED).

Design/Methods Simultaneous EEG-fMRI was performed on two patients with focal temporal epilepsy. We identified >10 events of brief (<2 s), isolated (>16 s apart) IEDs with identical morphology, and >10 IED events that do not fit these criteria. The former group of IEDs was analyzed by conventional methods. For the latter group of IEDs, a whole-brain pattern of fMRI signal correlation was computed for each voxel. The computation was then repeated for a group of time segments without IED to obtain another pattern of correlation at baseline. For each voxel, differences between the two patterns were summarized into a metric, namely the difference multiplied by the mean of the two correlation coefficients averaged across the whole brain.

Results In each patient, our analysis of non-brief or non-isolated IED events identified a cluster of voxels with large metric values representing significant differences in fMRI correlation patterns. Its location was consistent with both the scalp EEG and the conventional analysis using only the brief isolated IED events.

Conclusions Our new method can map various types of IEDs, in particular the non-brief non-isolated IED events, from simultaneous EEG-fMRI.

Authors/Disclosures
Junjie Liu PRESENTER	No disclosure on file
Barbara C. Jobst, MD, PhD, FAAN (Dartmouth-Hitchcock Med Ctr)	Dr. Jobst has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for AAN. The institution of Dr. Jobst has received research support from Neuropace, Inc.. The institution of Dr. Jobst has received research support from Harvard Pilgrim. The institution of Dr. Jobst has received research support from NIH. The institution of Dr. Jobst has received research support from CDC.
Terrance Darcey	No disclosure on file
Erik J. Kobylarz, MD, PhD (Dartmouth-Hitchcock Medical Center)	No disclosure on file
David K. Li, MD (University of British Columbia)	Dr. Li has received personal compensation in the range of $0-$499 for serving on a Scientific Advisory or Data Safety Monitoring board for Biogen. Dr. Li has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Biogen. Dr. Li has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Academy of Health Care Learning. Dr. Li has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Sanofi-Genzyme. Dr. Li has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Consortium of MS Centers.

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