Magnetic source imaging in non-lesional neocortical epilepsy: Additional value and comparison with ICEEG

Objective: To investigate the utility of magnetic source imaging (MSI) for localizing the epileptogenic zone (EZ) and predicting epilepsy surgery outcome in non-lesional neocortical focal epilepsy (NLNE) patients. Methods: Data from 18 consecutive patients with NLNE who underwent presurgical evaluation including intracranial electroencephalography (ICEEG) and MSI were studied. Follow-up after epilepsy surgery was +/- 24 months. Intracranial electroencephalography and MSI results were classified using a sublobar classification. Results: Sublobar ICEEG focus was completely resected in 15 patients; seizure-free rate was 60%. Eight patients showed sublobar-concordant ICEEG/MSI results and complete resection of both regions; seizure-free rate was 87.5%. Seizure-free rate in cases not matching these criteria was only 30% (p=0.013). Conclusions: Magnetoencephalography is a useful tool to localize the EZ and determine the site of surgical resection in NLNE patients. When sublobar concordance with ICEEG is observed, MSI increases the predictive value for a seizure-free epilepsy surgery outcome in these patients. (C) 2012 Elsevier Inc. All rights reserved.