Spatio-temporal source localization and Granger causality in ictal source analysis

Area of Science:

• Neuroscience
• Epileptology
• Biomedical Engineering

Background:

• Accurate localization of ictal onset zones is crucial for epilepsy surgery.
• Distinguishing primary seizure sources from secondary ones remains a challenge.
• Integrating spatio-temporal analysis with causal interaction estimation offers a novel approach.

Purpose of the Study:

• To introduce and validate a new ictal source analysis method combining spatio-temporal source localization and causal interaction estimation.
• To differentiate primary ictal sources initiating events from secondary sources resulting from propagation.
• To assess the clinical utility of this approach in presurgical evaluation for epilepsy patients.

Main Methods:

• The proposed method utilizes the Finite Impulse Response (FIR) estimation (FINE) approach for identifying neural electrical sources from scalp-electroencephalography (EEG) data.
• Granger causality estimation is employed on source waveforms derived from FINE to characterize causal interactions between neural sources.
• The analysis was applied to a case study of an epilepsy patient with symptomatic magnetic resonance imaging (MRI) lesions.

Main Results:

• The analysis successfully identified the primary ictal source within the visible MRI lesion.
• The method effectively distinguished the primary source from secondary sources based on causal interactions.
• The findings from the proposed analysis were consistent with the MRI findings for presurgical evaluation.

Conclusions:

• The combined spatio-temporal source localization and causal interaction estimation approach provides a robust method for ictal source analysis.
• This technique can accurately pinpoint the primary seizure focus, even in the presence of structural lesions.
• The proposed method holds promise for improving presurgical evaluation in epilepsy patients.