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Background: The identification of a biomarker for sudden unexpected death in epilepsy (SUDEP) has the potential to save lives. Generalized convulsive seizures and postictal generalized suppression on electroencephalography (EEG) most often precede sudden unexpected death in epilepsy (SUDEP) and are potential biomarkers. We identify the EEG and seizure characteristics associated with postictal generalized EEG suppression in children with epilepsy.Methods: Video EEGs were reviewed for seizure type, duration and semiology, and electrographic features. To identify predictors of postictal generalized EEG suppression, we identified 40 children with generalized convulsive seizures from a group of 399 patients who experienced an electroclinical seizure during video-EEG. Seventy-seven generalized convulsive seizures with and without postictal generalized EEG suppression were anayzed.Results: Age of seizure onset was older in 19 children with postictal generalized EEG suppression (mean 6.8 years old, 95% CI [4.7-8.9]) than in 21 without postictal generalized EEG suppression (3.0 years old, [1.1-4.1], P = 0.041). Postictal generalized EEG suppression occurred significantly more often from sleep than awake (point of estimate 16.67; 95% CI [0.97-32.36], P < 0.038). Shorter duration of the clonic phase (-0.76; [-1.338, -0.133], P = 0.018) was significantly associated with postictal generalized EEG suppression. Ictal symmetric tonic extension posturing significantly increased the odds of postictal generalized EEG suppression (42.94; [18.77, 67.12], P = 0.001). All 15 generalized convulsive seizures with a terminal burst-suppression pattern were followed by postictal generalized EEG suppression in contrast to 19 of 62 generalized convulsive seizures without burst-suppression (15.32, P < 0.001).Conclusions: Ictal decerebrate-like symmetric tonic extension posturing with shorter clonic phase and a terminal burst-suppression pattern identify malignant generalized convulsive seizures, associated with postictal generalized EEG suppression and a potentially increased risk of sudden unexpected death in epilepsy. [ABSTRACT FROM AUTHOR]

Objective A post-spike slow wave (PSS) as part of a spike and slow wave is presumably related to inhibition of epileptic activity. In this study, we evaluated dynamic changes of PSS power toward seizure onset in patients with focal cortical dysplasia (FCD) type II. Methods We collected data from 10 pediatric patients with FCD type II, who underwent invasive monitoring with subdural grids. The PSS were averaged based on spike-triggering in 30 s epochs during both interictal and preictal periods. We quantitatively measured and compared PSS power and distribution between interictal and preictal periods, both within and outside the seizure onset zone (SOZ). Results PSS power was significantly higher in all areas during preictal period compared with interictal period. During preictal period, PSS power within SOZ was significantly higher than outside SOZ. From interictal to preictal period, the number of electrodes with high power PSS significantly increased within SOZ and decreased outside SOZ. Conclusions Toward seizure onset, PSS power increased in all areas, predominantly within SOZ, and became confined into SOZ in a subset of FCD type II patients. Significance Preictal PSS power increase and confinement into SOZ accompany transition to seizures. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]