Magnetoencephalography distributed source modeling identifies spatiotemporal propagation patterns of interictal...

Magnetoencephalography (MEG) is an important adjunctive method used to localize interictal epileptiform discharges (IEDs). The equivalent current dipole (ECD) method, the current gold standard modeling approach, identifies a single point source of activity. However, IEDs propagate widely and may be better represented by distributed source modeling approaches. Here, we investigate how areas of maximal IED-related activity estimated using dynamic statistical parametric mapping (dSPM) compare to dipoles and surgical resections.

We analyzed resting-state MEG recordings from 38 NIH patients. We localized areas of IED-related activity along the IED rising phase and peak using spatial clustering of the top 5% of dSPM activations, comparing localizations to ECD and surgical resection areas in seizure free patients.

We identified dominant primary activation clusters in all patients and non-primary clusters in 24/38 patients. Dipoles localized closer to primary than non-primary clusters. In 12 post-operative seizure-free patients, the primary cluster center of mass was significantly closer to the resected area than dipoles and more stable over time.

Distributed source modeling adds to our understanding of IED propagation patterns and may be useful in IED localization for epilepsy surgery planning.

dSPM enhances pre-surgical planning by refining IED localization, potentially improving surgical outcomes.