Interictal Epileptiform Discharge Dynamics in Peri-sylvian Polymicrogyria Using EEG-fMRI

Area of Science:

• Neuroscience
• Epileptology
• Medical Imaging

Background:

• Polymicrogyria (PMG) is a common cortical malformation linked to epilepsy.
• Seizures in PMG patients often have complex, hard-to-localize sources.
• Identifying seizure origins is vital for treating drug-resistant focal epilepsy.

Purpose of the Study:

• To investigate the dynamics of interictal epileptiform discharges (IEDs) in patients with unilateral peri-sylvian polymicrogyria (PSPMG).
• To evaluate if simultaneous EEG-fMRI can reveal the precise cerebral sources of epileptic activity.
• To explore the potential of early hemodynamic activity for localizing seizure origins.

Main Methods:

• Case series involving four patients with PSPMG.
• Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) recordings.
• Tracking Blood-Oxygen-Level-Dependent (BOLD) activations before, during, and after IEDs on EEG.

Main Results:

• Focal BOLD activations within the PMG lesion consistently preceded EEG-identified IEDs.
• IED appearance on EEG correlated with stronger, more widespread brain activations.
• Early hemodynamic changes within the lesion suggest localized seizure initiation.

Conclusions:

• Early hemodynamic activity associated with IEDs may provide crucial localizing information for seizure sources.
• IEDs in PSPMG might originate in small, structurally complex areas, with later engagement of wider brain regions.
• This approach offers potential for improved localization in drug-resistant focal epilepsy secondary to PMG.