Fast oscillations >40 Hz localize the epileptogenic zone: An electrical source imaging study using high-density...

Area of Science:

• Neuroscience
• Epileptology
• Biomarkers

Background:

• Fast Oscillations (FO) >40 Hz are a potential biomarker for the epileptogenic zone (EZ).
• Evidence for FO detection using scalp electroencephalography (EEG) is limited.
• High-density EEG (HD-EEG) offers increased spatial resolution for source localization.

Purpose of the Study:

• To evaluate the utility of electrical source imaging of FO using 256-channel HD-EEG for identifying the EZ.
• To assess the accuracy of FO localization compared to surgical outcomes.

Main Methods:

• Analysis of HD-EEG recordings from 10 focal drug-resistant epilepsy patients with successful surgical outcomes.
• Identification and verification of FO events.
• Electrical source imaging of spikes and FO using the Maximum Entropy of the Mean framework.
• Validation of source localization maps against the surgical cavity.

Main Results:

• FO were identified in 50% of patients with superficial or intermediate deep generators.
• FO source localization maps accurately identified the EZ within the surgical cavity in 100% of cases.
• Reduced electrode coverage (10-10 and 10-20 systems) significantly decreased localization accuracy (60% and 40%, respectively).

Conclusions:

• Fast Oscillations (FO) recorded with HD-EEG effectively localize the epileptogenic zone (EZ).
• HD-EEG provides superior detection and localization of FO compared to conventional EEG methods.
• This study demonstrates the potential of FO localization using HD-EEG as a viable EZ marker.