Combining Electrical and Magnetic Fields for Source Analysis: A(n) Attractive or Repelling Thought. Issue 5 (September 2019)

• Record Type: Journal Article
• Authors: Shih, Jerry J.
• Is Part Of: Epilepsy currents. Volume 19:Issue 5(2019)
• Page Start: 291
• Page End: 293
• Publication Date: 2019-09
• Subjects: Epilepsy -- Periodicals; 616.853005
• DOI: 10.1177/1535759719868692
• Languages: English
• ISSNs: 1535-7597

Abstract

Electromagnetic Source Imaging in Presurgical Workup of Patients With Epilepsy: A Prospective Study. Duez L, Tankisi H, Hansen PO, et al. Neurology . 2019;92(6):e576-e586. doi:10.1212/WNL.0000000000006877 . Epub 2019 Jan 4. PMID: 30610090 Objective: To determine the diagnostic accuracy and clinical utility of electromagnetic source imaging (EMSI) in presurgical evaluation of patients with epilepsy. Methods: We prospectively recorded magnetoencephalography (MEG) simultaneously with electroencephalogram (EEG) and performed EMSI, comprising electric source imaging, magnetic source imaging, and analysis of combined MEG-EEG data sets, using 2 different software packages. As reference standard for irritative zone (IZ) and seizure onset zone (SOZ), we used intracranial recordings and for localization accuracy outcome 1 year after operation. Results: We included 141 consecutive patients. Electromagnetic source imaging showed localized epileptiform discharges in 94 (67%) patients. Most (72%) of the epileptiform discharge clusters were identified by both modalities, 15% only by EEG, and 14% only by MEG. Agreement was substantial between inverse solutions and moderate between software packages. Electromagnetic source imaging provided new information that changed the management plan in 34% of the patients, and these changes were useful in 80%. Depending on the method, EMSI had a concordance of 53% to 89% with IZ and 35% to 73% with SOZ. Localization accuracy of EMSI was between 44% and 57% which was not significantly different from magnetic resonance imaging (49%-76%) and PET (54%-85%). Combined EMSI achieved significantly higher odds ratio compared to electric source imaging and magnetic source imaging. Conclusion: Electromagnetic source imaging has accuracy similar to established imaging methods and provides clinically useful, new information in 34% of the patients. Classification of evidence: This study provides class IV evidence that EMSI had a concordance of 53% to 89% and 35% to 73% (depending on analysis) for the localization of epileptic focus when compared to intracranial recordings (IZ and SOZ), respectively.