How to record high-frequency oscillations in epilepsy: A practical guideline

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• High-frequency oscillations (HFOs) recorded in the 80-500 Hz range offer novel information for localizing epileptogenic brain tissue.
• Despite their discovery two decades ago, questions persist regarding HFOs' utility as biomarkers and their clinical application in epilepsy surgery planning.

Purpose of the Study:

• To provide practical, technical guidance on recording, evaluating, and interpreting HFOs (ripples, fast ripples, and very high-frequency oscillations).
• To address challenges in HFO analysis and facilitate their clinical translation.

Main Methods:

• Review of current technologies and methodologies for HFO detection and analysis.
• Emphasis on low-noise recording techniques to minimize artifacts.
• Discussion of artifact sources (muscle, movement, filtering) impacting both magnetoencephalography and intracranial electroencephalography (iEEG) recordings.

Main Results:

• Low-noise recording is crucial for accurate HFO identification.
• HFO analysis, whether visual or automated, remains challenging due to artifacts.
• Both magnetoencephalography and iEEG are susceptible to similar artifact types.

Conclusions:

• High-frequency oscillations show promise as biomarkers for epilepsy.
• This review synthesizes the current state of HFO recording and identification.
• Potential challenges to the clinical translation of HFOs are highlighted.