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Objective: To investigate how rewarming impacts the evolution of EEG background in neonates with hypoxic-ischemic encephalopathy (HIE) undergoing therapeutic hypothermia (TH)., Methods: We recruited a retrospective cohort of 15 consecutive newborns with moderate (9) and severe (6) HIE monitored with a continuous EEG during TH and at least 12h after its end. EEG background was analyzed using conventional visual and quantitative EEG analysis methods including EEG discontinuity, absolute and relative spectral magnitudes. One patient with seizures on rewarming was excluded from analyses., Results: Visual and quantitative analyses demonstrated significant changes in EEG background from pre- to post-rewarming, characterized by an increased EEG discontinuity, more pronounced in newborns with severe compared to moderate HIE. Neonates with moderate HIE also had an increase in the relative magnitude of slower delta and a decrease in higher frequency theta and alpha waves with rewarming., Conclusions: Rewarming affects EEG background in HIE newborns undergoing TH, which may represent a transient adaptive response or reflect an evolving brain injury., Significance: EEG background impairment induced by rewarming may represent a biomarker of evolving encephalopathy in HIE newborns undergoing TH and underscores the importance of continuously monitoring the brain health in critically ill neonates., (Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.)

Purpose: We present two methods of implantation for the investigation of suspected insular and perisylvian epilepsy that combine depth and subdural electrodes to capitalize on the advantages of each technique., Methods: Retrospective study of all intracranial EEG studies that included insular electrodes from 2004-2010. Patients were divided according to the implantation scheme. The first method (type 1) consisted of a craniotomy, insertion of insular electrodes after microdissection of the sylvian fissure, orthogonal implantation of mesiotemporal structures with neuronavigation, and coverage of the adjacent lobes with subdural electrodes. The second method (type 2) consisted of magnetic resonance imaging (MRI)-stereotactic frame-guided depth electrode implantation into insula and hippocampus using sagittal axes, and insertion of subdural electrodes through burr holes to cover the adjacent lobes. The combined implantations were developed and performed by one neurosurgeon (AB)., Key Findings: Nineteen patients had an intracranial study that sampled the insula, among other regions. Sixteen patients were implanted using the first method, which allowed a mean of 4, 5, 20, 15, and 42 contacts per patient to be positioned into/over the insular, mesial temporal, neocortical temporal, parietal, and frontal areas, respectively. The second method (three patients) allowed a mean of 8, 7, 16, 6, and 9 contacts per patient to sample the same areas, respectively. The four patients in whom transient neurologic deficits occurred were investigated with use of type 1 implantation., Significance: Combined depth and subdural electrodes can be used safely to investigate complex insular/perisylvian refractory epilepsy. Choice of implantation scheme should be individualized according to presurgical data and the need for functional localization., (Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.)

Gamma band electroencephalography (EEG) abnormalities have been reported in patients with epilepsy. We aimed to investigate whether patients with febrile seizures (FS) show abnormalities of the gamma frequency steady-state visual evoked potential (SSVEP) components evoked by intermittent photic stimulation (IPS). We analyzed the magnitude and phase alignment of the 50–100 Hz SSVEP components elicited by IPS from 12 FS patients, 5 siblings of FS patients, and 15 control children between 6 and 36 months of age. Patients with FS showed significantly higher SSVEP magnitude and phase alignment values when compared to both the siblings and control groups. Detected abnormalities could either represent the direct consequence of seizures or indicate a preexisting tendency to hypersynchrony in FS patients. Future prospective studies could assess whether SSVEP abnormalities are associated with complex rather than simple FS, or have a prognostic value for the development of epilepsy following FS. [ABSTRACT FROM AUTHOR]

Seizures are common and worsen the outcome in critically ill neonates. Predicting seizure recurrence could allow individualizing antiepileptic treatment and improving the outcome. To identify EEG signatures of seizure recurrence, we investigated periictal spectral power and electrographic characteristics of seizures in five consecutive asphyxiated neonates under continuous EEG monitoring. All patients had high seizure burden while undergoing hypothermic neuroprotection. Two neonates had recurrence of seizures on rewarming. Spectral power analysis of fifteen artifact-free consecutive ictal events demonstrated, in all neonates, a significant increase in overall spectral power from the interictal to preictal and ictal periods ( p < 0.01). Delta frequency power increase was consistently observed in all patients. Alpha power increase was more pronounced in the two patients with recurrence of seizures on rewarming and significant when comparing both interictal-to-preictal and interictal-to-ictal periods. In these two patients, preictal and ictal alpha activity displayed a regional, hemispheric or even diffuse distribution contrasting with the focal seizure onset. This distinct alpha activity preceding ictal onset could represent a biomarker of propensity for seizure recurrence. Future studies should be performed to confirm whether quantitative periictal characteristics and electrographic features allow predicting the risks of seizure recurrence in asphyxiated hypothermic neonates and other critically ill patients. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the development of the magnitude and phase alignment of steady-state visual evoked potentials induced by 5Hz intermittent photic stimulation in 46 children (3 to 16years) and 8 adults, as a function of age. We found that, over the occipital region, magnitude values were the highest in 8–11-year old children, but decreased with age over all other cerebral regions. Phase alignment values increased with age over the occipital, parietal and frontal cerebral regions. We interpret these findings in terms of the development of functional interactions between different cortical areas involved in the processing of visual stimuli. [Copyright &y& Elsevier]