Causality within the Epileptic Network: An EEG-fMRI Study Validated by Intracranial EEG

Area of Science:

• Neuroscience
• Medical Imaging
• Epileptology

Background:

• Accurate Seizure Onset Zone (SOZ) localization is critical for drug-resistant focal epilepsy surgery.
• Electroencephalography with functional Magnetic Resonance Imaging (EEG-fMRI) is a non-invasive tool for pre-surgical evaluation.
• fMRI maps of interictal epileptiform activities (IED) often reveal widespread networks, complicating focal SOZ identification.

Purpose of the Study:

• To validate Dynamic Causal Modeling (DCM) for analyzing EEG-fMRI data in identifying the epileptogenic network driver.
• To assess DCM's utility in localizing the SOZ in a patient with frontal lobe epilepsy.

Main Methods:

• Applied DCM to EEG-fMRI data from a patient with frontal lobe epilepsy.
• Analyzed blood oxygenation level dependent (BOLD) signal changes related to IED.
• Compared DCM results with EEG source imaging (ESI) and psycho-physiological interaction analysis.

Main Results:

• EEG-fMRI showed BOLD signal increases in the left frontal pole and ipsilateral dorso-lateral frontal cortex.
• DCM identified the left dorso-lateral frontal cortex as the driver of activity in the fronto-polar region.
• DCM findings were consistent with subsequent intracranial EEG monitoring, confirming the SOZ in the dorso-lateral frontal cortex.

Conclusions:

• DCM applied to EEG-fMRI data is a promising method for identifying the epileptogenic network driver.
• This approach can provide crucial information for epilepsy surgery planning.
• Combining EEG-fMRI with advanced BOLD signal analysis enhances SOZ localization accuracy.