Symposium 6. Epilepsy: Advanced EEG in clinical practice SY6.1. Infraslow, DC shift and high frequency oscillations: Established tool or research topic?

Abstract

Since 1990s digital EEG has been rapidly introduced and almost replaced analogue EEG, and currently furthermore wide-band EEG is clinically available. It ranges from infraslow or DC shifts (since 1990s) to high frequency oscillation (HFO) such as over 300Hz or even 1kHz (since 2000s) depending on the degree of sampling rate. Therefore, currently clinical EEG may belong to the 2nd generation of digital EEG as “wide-band EEG era”. Therefore, it is very important to differentiate those digital EEG features as to whether they are already established tools or still research topics. Research topics can be divided into biological research topics. It includes infraslow or DC shifts. Ictal infraslow or DC shifts has been extensively investigated as the research topics in basic and clinical fields, and at least a part of them (invasive ictal DC shifts) is very close to a tool (Nakatani et al, 2018). Among pathological HFO, interictal, invasive HFO is at least partly regarded as a tool. Physiological HFO such as language and memory are actively investigated as the research topics. Mathematical EEG data analysis with clear hypothesis or condition is also regarded as methodological research topics (3D source analysis, Granger causality analysis, etc). Clinical tools are also listed as follows; quantitative EEG analysis such as frequency band mapping, time-frequency analysis and voltage map. Those are strong tools for clinical practice and for clinical research for CNS function and its pathological state.