106 Functional Network Analysis in Surgical Epilepsy Patients Using Magnetoencephalography. (August 2015)

• Record Type: Journal Article
• Authors: Englot, Dario J.; Knowlton, Robert C.; Chang, Edward F.; Kirsch, Heidi E.; Nagarajan, Srikantan S.
• Is Part Of: Clinical neurosurgery. Volume 62(2015)Supplement 1
• Publication Date: 2015-08
• Subjects: Nervous system -- Surgery -- Congresses; Neurosurgery; Nervous system -- Surgery; Neurologie; Congresses; Conference papers and proceedings; 617.48
• DOI: 10.1227/01.neu.0000467068.09682.e5
• Languages: English
• ISSNs: 0069-4827

Abstract

Abstract : INTRODUCTION: Intractable focal epilepsy is a devastating disorder with profound effects on cognition and quality of life. Epilepsy surgery can lead to seizure freedom in patients with focal epilepsy; however, sometimes it fails owing to an incomplete delineation of the epileptogenic zone (EZ). Brain networks in epilepsy can be studied with resting-state functional connectivity (RSFC) analysis, yet previous investigations using functional MRI or electrocorticography have produced inconsistent results. Magnetoencephalography (MEG) allows noninvasive whole-brain recordings, and can be used to study both long-range network disturbances in focal epilepsy and regional connectivity at the EZ. METHODS: In MEG recordings from presurgical epilepsy patients, we examined: (1) global functional connectivity maps in patients vs controls, and (2) regional functional connectivity maps at the region of resection, compared with the homotopic nonepileptogenic region in the contralateral hemisphere. RESULTS: Sixty-one patients were studied, including 30 with mesial temporal lobe epilepsy and 31 with focal neocortical epilepsy. Compared with a group of 31 controls, epilepsy patients had decreased RSFC in widespread regions, including perisylvian, posterior temporoparietal, and orbitofrontal cortices ( P < .01, false discovery rate-corrected). Decreased mean global connectivity was related to longer duration of epilepsy and higher frequency of consciousness-impairing seizures ( P < .01, linear regression). Furthermore, patients with increased regional connectivity within the resection site (n = 24) were more likely to achieve postoperative seizure freedom (87.5% with Engel I outcome) than those with neutral (n = 15, 64.3% seizure free) or decreased (n = 23, 47.8% seizure free) regional connectivity ( P < .02, χ 2 ). CONCLUSION: Widespread global decreases in functional connectivity are observed in patients with focal epilepsy and may reflect deleterious long-term effects of recurrent seizures. Furthermore, enhanced regional functional connectivity at the area of resection may help predict seizure outcome and aid surgical planning.