Abstract Details

Title Alpha-gamma Frequencies and Their Possible Role in Seizure Evolution

Topic Epilepsy/Clinical Neurophysiology (EEG)

Presentation(s) S28 - (-)

Poster/Presentation
Number 006

Objective

Background Previous studies of HFO from intracranial microelectrodes and/or single neuron recordings emphasized frequencies above 100 Hz as being a more significant bio marker of the epileptogenic region.

Design/Methods Ten patients with medically refractory partial epilepsy undergoing commercially available intracranial macroelectrode monitoring (5 depth electrodes, 5 subdural grids) were analyzed. Digital EEG data was sampled at 2 kHz at various intervals. Multiband frequency and power analysis were performed to characterize the predominating frequency during the interictal, pre-ictal, ictal, and postictal periods.

Results Thirty-three seizures[mdash]15 seizures collected from subdural grid and 18 from depth electrodes[mdash]were analyzed. In seven patients who remained seizure free post-operatively, their 19 seizures demonstrated a significant increase in 10-30 Hz frequencies 2-5 seconds before the appearance of HFO in selected contacts. Focal surgical resections were performed in the areas correlated to the synchronization of these alpha-gamma range frequencies and HFO prior to and during the patients' clinical seizures, thus confirming the localization of seizure onset. In contrast, 14 seizures from three patients who did not become seizure-free post-operatively did not demonstrate the synchronization of alpha-gamma range frequencies.

Conclusions In our study, alpha-gamma frequencies activity preceding the more typical HFO pattern and their associated synchronization correlated with post-operative seizure freedom. Our study suggests that HFO may not be the first ictal manifestation in some cases, and defining the frequencies that best represent the initial ictal onset zone remains to be determined.

Authors/Disclosures
John R. Jefferson, MD (Seton) PRESENTER	Dr. Jefferson has nothing to disclose.
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Pieter Van Doorn, MD (Erasmus University Medical Center)	The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Hansa. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Octapharma. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Roche. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Anexxon. The institution of Dr. Van Doorn has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Grifols. Dr. Van Doorn has received publishing royalties from a publication relating to health care.
	No disclosure on file
Evgeny Tsimerinov, MD, PhD, FAAN (Neurology, Inc)	No disclosure on file
	No disclosure on file
Dawn Eliashiv, MD, FAAN (UCLA)	Dr. Eliashiv has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Neuropace. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Medtronic. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for UCB. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for eisai. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for SK Lifesciences. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for UCB. Dr. Eliashiv has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Medtronic's. Dr. Eliashiv has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for neuropace. The institution of Dr. Eliashiv has received research support from NINDS. The institution of Dr. Eliashiv has received research support from Neuropace. Dr. Eliashiv has received publishing royalties from a publication relating to health care.
Jeffrey M. Chung, MD, FAAN (Cedars-Sinai Medical Center)	Dr. Chung has received personal compensation in the range of $500-$4,999 for serving as an Expert Witness for Asvar Law. Dr. Chung has received personal compensation in the range of $500-$4,999 for serving as a Consultant with Oak Crest Institute of Science.

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