High-Frequency Oscillations Recorded on the Scalp of Patients with Epilepsy Using Tripolar Concentric Ring Electrodes

June 30, 2014
Panel B shows 12 minutes of bipolar EEG from Fp2-F4 (1-70 Hz, 200 S/s). Panel A is the corresponding spectrogram. Panel E shows 30 seconds of EEG from Panel B at the onset of the generalized seizure (dashed line). Panels C, D, and F are the corresponding tEEG signals from Fp2’ (1-100 Hz, 200 S/s). Note the high gamma-band burst HFOs just prior to the partial seizure (highlighted by ellipse in panel C).

Panel B shows 12 minutes of bipolar EEG from Fp2-F4 (1-70 Hz, 200 S/s). Panel A is the corresponding spectrogram. Panel E shows 30 seconds of EEG
from Panel B at the onset of the generalized seizure (dashed line). Panels C, D, and F are the corresponding tEEG signals from Fp2’ (1-100 Hz, 200 S/s). Note
the high gamma-band burst HFOs just prior to the partial seizure (highlighted by ellipse in panel C).

Epilepsy is the second most prevalent neurological disorder (~1% prevalence) affecting approximately 67 million people worldwide with up to 75% from developing countries. The conventional electroencephalogram is plagued with artifacts from movements, muscles, and other sources. Tripolar concentric ring electrodes automatically attenuate muscle artifacts and provide improved signal quality. We performed basic experiments in healthy humans to show that tripolar concentric ring electrodes can indeed record the physiological alpha waves while eyes are closed. We then conducted concurrent recordings with conventional disc electrodes and tripolar concentric ring electrodes from patients with epilepsy. We found that we could detect high frequency oscillations, a marker for early seizure development and epileptogenic zone, on the scalp surface that appeared to become more narrow-band just prior to seizures. High frequency oscillations preceding seizures were present in an average of 35.5% of tripolar concentric ring electrode data channels for all the patients with epilepsy whose seizures were recorded and absent in the corresponding conventional disc electrode data. An average of 78.2% of channels that contained high frequency oscillations were within the seizure onset or irritative zones determined independently by three epileptologists based on conventional disc electrode data and videos.

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Authors

See complete bios of the authors in the full version of this article.

W BesioW Besio
Dr. Besio is an Associate Professor in the Electrical, Computer, and Biomedical Engineering Department at the University of Rhode Island. His laboratory performs research to develop innovative biomedical instrumentation for diagnosis and therapies for enhancing the lives of persons with disease and disability.

I Martinez-JuarezI Martinez-Juarez
Dr. Martínez-Juárez is a Neurologist-Epileptologist and Head of the Epilepsy Clinic, National Institute of Neurology and Neurosurgery, Mexico, Professor of Clinical Epileptology Fellowship, National Autonomous University of Mexico (UNAM) and National Institute of Neurology and Neurosurgery, Mexico. Her research interests are in juvenile myoclonic epilepsy and genetics of epilepsy.

O MakeyevO Makeyev
Dr. Makeyev is with the Department of Electrical, Computer, and Biomedical Engineering at the University of Rhode Island, Kingston, RI. His broad research interests include development and application of computational intelligence and statistics based signal processing and pattern recognition methods to engineering problems with an emphasis on biomedical engineering.

J GaitanisJ Gaitanis
Dr. Gaitanis is an Associate Professor of Neurology and Pediatrics (clinical) at the Warren Alpert Medical School of Brown University and the Director of Pediatric Epilepsy at Hasbro Children’s Hospital. His research interests include brain malformations, pediatric epilepsy, and use of electroencephalography in the diagnosis of neurological conditions.

A BlumA Blum
Dr. Blum is an Associate Professor of Neurology at the Alpert Medical School of Brown University. His current research interests focus upon epilepsy co-morbidities, particularly psychiatric and cognitive concerns, epilepsy in older populations, and the pathophysiology of epileptic seizures including mechanisms germane to SUDEP, sudden unexplained death in epilepsy.

R FisherR Fisher
Dr. Fisher is is Maslah Saul MD Professor and Director of the Stanford Epilepsy Center. He received the Ambassador Award from the International League Against Epilepsy, the 2005 AES Service Award, and the 2006 Annual Clinical Research Award. He has served on the Board of the ILAE and as Editor-in-Chief of the Journal, Epilepsia. His research is on new devices to treat epilepsy.

A MedvedevA Medvedev
Dr. Medvedev is a neurophysiologist and computational neuroscientist. His expertise includes systems electrophysiology, high density EEG, source localization, near-infrared optical brain imaging, functional connectivity, signal analysis and neural network modeling. Dr. Medvedev’s research focuses on neural mechanisms of cognitive processes in healthy participants as well as patients with various neurological disorders.

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