Spatiotemporal propagation patterns of generalized ictal spikes in childhood absence epilepsy Vasileios Kokkinos a,b,⇑ , Andreas M. Koupparis b , Michalis Koutroumanidis a , George K. Kostopoulos b a Department of Clinical Neurophysiology and Epilepsies, Guy’s, St Thomas’ and Evelina Hospital for Children, NHS Foundation Trust, London, United Kingdom b Neurophysiology Unit, Department of Physiology, Medical School, University of Patras, Greece article info Article history: Accepted 31 May 2017 Available online 17 June 2017 Keywords: Benign childhood epilepsies EEG Childhood absence epilepsy Ictal spikes Generalized discharges highlights  Generalized ictal spikes have propagation patterns of high intra- and low inter-patient consistency.  Generalized ictal spike propagation patterns transform into lateralized diminished forms.  Generalized ictal spike propagation patterns transform into non-lateralized reverse direction forms. abstract Objective: This work investigates the spatial distribution in time of generalized ictal spikes in the typical absences of childhood absence epilepsy (CAE). Methods: We studied twelve children with CAE, who had more than two typical absences during their routine video-EEG. Seizures were identified, and ictal spikes were marked over the maximum electroneg- ative peak, clustered, waveform-averaged and spatiotemporaly analyzed in 2D electrode space. Results: Consistency of spatiotemporal patterns of ictal spikes was high between the absences of the same child, but low between children. Three main discharge patterns were identified: of anterio- posterior propagation, of posterio-anterior propagation and confined to the frontal/prefrontal regions. In 4 patients, the propagation patterns transformed during the seizure into either a lateralized dimin- ished or a non-lateralized reverse direction form. Most spikes originated fronto-temporaly, all maximized over the frontal/prefrontal electrodes and mostly decayed prefrontaly. In 4 patients, lateralized propaga- tion patterns were identified. Conclusions: Ictal spike propagation patterns suggest that epileptogenic CAE networks are personalized, interconnect distal areas in the brain – not the entire cortex – with a tendency to generate bilateral sym- metrical discharges, sometimes unsuccessfully. The transformation of propagation patterns during the seizure indicates the existence of dynamic interplay within epileptogenic networks. Significance: Our results support the revised concept of ictogenesis of ILAE definition in genetic (also known as idiopathic) generalized epilepsies. Understanding the focal features in CAE avoids misdiagnosis as focal epilepsy and inappropriate treatment. Ó 2017 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. 1. Introduction Childhood absence epilepsy (CAE) is the prototype syndrome of genetic (idiopathic) generalized epilepsy (GGE/IGE) characterized by typical absence seizures (TAS) (Gibbs et al., 1935; Penfield and Jasper, 1954; ILAE 1989; Berg et al., 2010). TAS manifest as brief impairment of consciousness of sudden onset and offset, without aura or post-ictal symptoms (Panayiotopoulos et al., 1989), frequently accompanied by spontaneous eye-opening, star- ing, random eye-blinking and automatisms (Hirsch and Marescaux, 1994; Panayiotopoulos, 1997). The EEG background activity is gen- erally normal, and 2.5–4 Hz generalized spike-wave discharges (GSWDs) occur either interictally (when brief) or ictally as a con- tinuous sustained discharge (Duncan and Panayiotopoulos, 1995). The ictal GSWD is a high-amplitude generalized, bilateral syn- chronous, symmetrical rhythmic discharge with well-formed spikes that form a distinctive regular complex with the subsequent wave (Panayiotopoulos, 1997). http://dx.doi.org/10.1016/j.clinph.2017.05.021 1388-2457/Ó 2017 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved. ⇑ Corresponding author at: Neurophysiology Unit, Department of Physiology, Medical School, University of Patras, 26500, Greece. E-mail address: info@vasileioskokkinos.gr (V. Kokkinos). Clinical Neurophysiology 128 (2017) 1553–1562 Contents lists available at ScienceDirect Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph