Spatial Patterns and Variation in High-Frequency Oscillation Rates and Amplitudes in Intracranial EEG Recordings
Abstract number :
1.015
Submission category :
1. Translational Research: 1A. Mechanisms / 1A3. Electrophysiology/High frequency oscillations
Year :
2017
Submission ID :
340307
Source :
www.aesnet.org
Presentation date :
12/2/2017 5:02:24 PM
Published date :
Nov 20, 2017, 11:02 AM
Authors :
Hari Guragain, Mayo Clinic; Jan Cimbalnik, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czech Republic; Matt Stead, Mayo Clinic; David Groppe, The Krembil Neuroscience Centre, Toronto, Canada; Daniel Kenney-Jung, Ma
Rationale: High-frequency oscillations (HFOs) have been described as interictal or resting-state intracranial EEG (iEEG) biomarkers for the localization of seizure-generating brain tissue. However, HFOs can also play a role in normal cognitive processing. Accurate identification of seizure onset zone requires differentiation between pathological and physiological HFOs, and characterization of normal or non-pathological HFO activity in different brain regions. Methods: This study reports HFO (100-600 Hz) rates measured in 70 patients with intractable epilepsy who underwent wide-bandwidth iEEG as part of clinical presurgical assessment. Discrete HFOs were identified with an automated detector (Cimbalnik, Worrell, & Stead, 2016) in two-hour segments of high quality recordings likely to represent sleep. Electrode locations were determined by coregistering the patient’s pre-operative MRI with an x-ray CT image acquired immediately after electrode implantation. Electrode localization in standard MNI atlas space was performed using iELVis (Groppe, et al., 2016), and anatomic locations for each electrode provided by the Desikan-Killiany atlas incorporated in FreeSurfer (Desikan, et al., 2012). Results: HFO rates were measured in seizure onset zone (SOZ) and non-seizure onset zone (non-SOZ) for different anatomical structures in the brain. SOZ and non-SOZ were determined from the patient’s clinical iEEG study by one or more certified epileptologists. HFO rates were found to be significantly higher in SOZ than non-SOZ in aggregate, and individually in parietal and occipital lobes (p < 0.001) . HFO rates in mesial temporal structures (hippocampus and amygdala) were significantly higher than temporal neocortex (p < 0.003) . Conclusions: Rates of HFOs can vary significantly with the anatomic location of electrodes. The variation in SOZ and non-SOZ HFO rates for different brain regions highlights the importance of assessing HFO rates in the context of the anatomic locations of electrodes. Funding: The Mayo Clinic, National Institute of Health, The David Hawk Foundation.Institutional resources for research by Czech Technical University in Prague, Czech Republic, and the Czech Science Foundation: grant No. 17-20480S
Translational Research