Virtual Cortical Stimulation Mapping of Epilepsy Networks to Localize the Epileptogenic Zone

Area of Science:

• Neuroscience
• Computational Neuroscience
• Medical Engineering

Background:

• Cortical stimulation mapping (CSM) is crucial for localizing the epileptogenic zone (EZ) in epilepsy patients.
• Current CSM methods are limited by time constraints and potential patient harm, restricting comprehensive mapping.
• Identifying seizure onset zones is vital for targeted epilepsy treatment.

Purpose of the Study:

• To develop and validate a virtual CSM (vCSM) procedure using pre-seizure intracranial EEG data.
• To assess the efficacy of vCSM in localizing the EZ and predicting surgical outcomes.
• To enhance the diagnostic capabilities for epilepsy surgery planning.

Main Methods:

• A linear time-varying network (LTVN) model was identified from electrocorticography (ECoG) and stereo-EEG (SEEG) data using sparse least squares estimation.
• Virtual CSM was simulated by applying impulse perturbations to the LTVN model to measure network after-discharges (ADs).
• An impulse response ratio (IRR) metric was computed from AD heatmaps to compare EZ contacts with other regions.

Main Results:

• The vCSM procedure generated spatio-temporal heatmaps of ADs before, during, and after seizures.
• A higher IRR was observed in patients with successful surgical outcomes compared to those with failed outcomes.
• The findings suggest vCSM can provide valuable insights into EZ localization.

Conclusions:

• Virtual CSM offers a non-invasive approach to complement traditional CSM in epilepsy surgery.
• The IRR metric derived from vCSM shows potential as a predictor of surgical success.
• This computational method may improve the precision of EZ localization and treatment planning.