Spatial relationship between fast and slow components of ictal activities and interictal epileptiform discharges in epileptic spasms

Objective: We analyzed the spatial distribution and concordance of fast (>10 Hz) and slow (<5 Hz) electroencephalogram (EEG) components of ictal activities and interictal epileptiform discharges (IIED) recorded by intracranial video EEG (IVEEG) in children with epileptic spasms (ES). Methods: We studied eight children with ES, who underwent IVEEG before resective surgery for epilepsy. We quantified the root-mean-square (RMS) amplitude of the fast and slow components of ictal activities during ES and IIED. We compared the concordance between the spatial distributions of the fast and slow components of ES and IIED. Results: There was a larger concordance between the spatial distributions of the fast and slow components in IIED than in ES (p = 0.0206 and 0.0401). Conclusions: The spatial concordance between the fast and slow EEG components was significantly different between ES and IIED. Significance: The mechanisms underlying the generation of slow EEG components may differ between ES and IIED. The slow EEG components of ES might indicate an extensive epileptic network involving remote symptomatic zones for ES in either the cortical or subcortical areas. The high spatial concordance between the fast and slow components of IIED suggests the involvement of a local inhibitory process within the epileptic cortex. (C) 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.