EEG Ictal Power Dynamics, Function-Structure Associations, and Epilepsy Surgical Outcomes

Area of Science:

• Neuroscience
• Epilepsy Research
• Medical Imaging

Background:

• Postoperative seizure control in drug-resistant temporal lobe epilepsy (TLE) is variable.
• The underlying causes for variable surgical outcomes are not fully understood.
• Extensive spread of synchronized ictal activity may contribute to poor outcomes.

Purpose of the Study:

• To investigate how seizure spread is determined by structural network topology.
• To test the hypothesis that extensive seizure spread impacts postoperative seizure control.
• To develop novel quantifiable assessments from intracranial EEG (iEEG) for epilepsy research.

Main Methods:

• Analyzed iEEG data from 157 seizures in 27 TLE patients (favorable vs. unfavorable outcomes).
• Developed a quantifiable method to measure seizure power dynamics within anatomical regions.
• Mapped time-frequency power spectrums onto individual MRIs and compared spatiotemporal dynamics and structural connectivity (FA).

Main Results:

• Seizures in patients with unfavorable outcomes showed significantly larger maximum activation sizes.
• Faster spread of beta-band power (within 1 second) was observed in unfavorable outcome seizures.
• A significant correlation between beta power and fractional anisotropy (FA) was found, especially in the unfavorable outcome group.

Conclusions:

• Ictal iEEG power dynamics are mechanistic factors associated with surgical outcomes in TLE.
• The structural-functional relationship between brain networks and seizure activity influences surgical success.
• Integrating structural and functional data may improve prediction of epilepsy surgery outcomes.