Electromagnetic source imaging predicts surgical outcome in children with focal cortical dysplasia

To evaluate the diagnostic accuracy of electromagnetic source imaging (EMSI) in localizing spikes and predict surgical outcome in children with drug resistant epilepsy (DRE) due to focal cortical dysplasia (FCD).

We retrospectively analyzed magnetoencephalography (MEG) and high-density (HD-EEG) data from 23 children with FCD-associated DRE who underwent intracranial EEG and surgery. We localized spikes using equivalent current dipole (ECD) fitting, dipole clustering, and dynamical statistical parametric mapping (dSPM) on EMSI, electric source imaging (ESI), and magnetic source imaging (MSI). We calculated the distance from the seizure onset zone (D_SOZ) and resection (D_RES). We estimated receiver operating characteristic (ROC) curves with Youden's index (J) to predict outcome.

EMSI presented shorter D_SOZ (15.18 ± 9.06 mm) and D_RES (8.56 ± 6.24 mm) compared to ESI (D_SOZ: 25.04 ± 16.20 mm, p < 0.009; D_RES: 18.88 ± 17.30 mm, p < 0.03) and MSI (D_SOZ: 23.37 ± 8.98 mm, p < 0.03; D_RES: 15.51 ± 10.11 mm, p < 0.02) for clustering in patients with good outcome. Clustering showed shorter D_SOZ and D_RES compared to ECD fitting and dSPM (p < 0.05). EMSI had higher performance as outcome predictor (J = 70.63%) compared to ESI (J = 41.27%) and MSI (J = 33.33%) for clustering.

EMSI provides superior localization and improved predictive performance than individual modalities.

EMSI can help the surgical planning and facilitate the localization of epileptogenic foci.