Abstracts

Rationale: To analyze chronological changes in phase-amplitude coupling (PAC) and verify whether PAC analysis can diagnose epileptogenic zones during seizures.

Methods:

We analyzed 30 seizures in 10 patients with mesial temporal lobe epilepsy who had ictal discharges with preictal spiking followed by low-voltage fast activity patterns on intracranial electroencephalography. We used the amplitude of two high-frequency bands (ripples: 80-200 Hz, fast ripples: 200-300 Hz) and the phase of three slow wave bands (0.5-1 Hz, 3-4 Hz, and 4-8 Hz) for modulation index (MI) calculation from 2 minutes before seizure onset to seizure termination. We evaluated the accuracy of epileptogenic zone detection by MI, in which a combination of MI was better for diagnosis and analyzed patterns of chronological changes in MI during seizures.

Results:

 MI_{Ripples/3-4 Hz} and MI_{Ripples/4-8 Hz} in the hippocampus were significantly higher than those in the peripheral regions from seizure onset. Corresponding to the phase on intracranial electroencephalography, MI_{Ripples/3-4 Hz} decreased once and subsequently increased again. MI_{Ripples/4-8 Hz} showed continuously high values.

Conclusions: Continuous measurement of MI_{Ripples/3-4 Hz} and MI_{Ripples/4-8 Hz} could help identify epileptogenic zones.

Funding: JST CREST (Grant No. JPMJCR20F1 and 21-181028507) and JSPS KAKENHI (Grant No. 21 K09160)