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Introduction Many questions concerning the mechanisms that drive neurons to hypersynchronize remain unsolved, but synaptic as well as non-synaptic events are likely to be involved. Here Optical Imaging (OI) of the epileptic brain by concomitant electroencephalography (FOS-ECoG/HD-EEG), allow investigating the changes in the cellular environment associated with Interictal Epileptic Spikes (IES). The FOS changes (milliseconds) are related to non-synaptic events neuronal activation while ECoG-HDEEG investigates the synaptic events related to the IES. Methods In 3 patients with frontal epileptic spikes, High-Density EEG (HD-EEG) was acquired with 64 electrodes. In 15 epileptic penicillin rats’ experiments, ECoG signals were acquired with two monopolar electrodes disposed over the somatosensory cortex. FOS were recorded with a frequency-domain spectrophotometer at a sampling rate of 62.5 Hz with 16/2 detectors and 4/2 sources in patients and rats respectively. In order to provide an independent control condition to evaluate the method and the specificity of FOS in IES, the FOS signal in response to electrical stimulation of the median nerve was evaluated in both species. Results In both species median nerve stimulation (mERP) induces similar changes in FOS signal consisted in an increase followed by a decrease in the FOS concomitant to the mERP. In both species, alternating increase–decrease-increase in FOS occurred 200 ms before to 180 ms after the IES peak. This started before any changes in EEG signal. Time–frequency domain ECoG-HD EEG analysis revealed alternating decrease-increase–decrease in the EEG spectral power concomitantly with changes in FOS during IES. The FOS response was weaker with a lower signal-to-noise ratio when recorded on the scalp than when recorded from the cortex.This suggests a tight relationship between (de) synchronization and neuronal volume changes during IES. Conclusion FOS-ECoG/HDEEG analysis revel complex changes surrounding the IES and illustrating the complexity of the underlying mechanisms of IES generation. These changes in the neuronal environment around IES in frontal lobe epilepsy in children and in rats raise new questions about the synaptic and non-synaptic mechanisms that propel the neurons to IES hypersynchronization. Because it unable to evaluate non-invasively the synaptic and non-synaptic compartments, this multiscale multimodal high temporal resolution approach offer the opportunity to thoroughly investigate the pathophysiology of the IES. FOS response was specific to exogenous stimuli or endogenous neuronal activation (IES). The observed responses in epileptic patients were similar to those on epileptic rats using similar acquisition protocol and data analysis processes. This suggests that the mechanisms involved are fairly specific to the epileptic spikes, independently of the species and of the type of epilepsy.

EEG is an important tool for early cerebral evaluation in neonatal hypoxo-ischemic encephalopathy (HIE). The aim of our study was to precise the EEG prognosis value before starting hypothermia and during 72 h hypothermia in neurodevelopment evaluation with at least 2 years clinical follow-up. We analyzed 98 newborns admitted for suspicion of HIE. First EEG was done before 6 h of life, it was surveyed continuously and analyzed twice a day during 72 H hypothermia and in 12 h following rewarming. EEG recordings were characterized according to the French classification. The neurologic outcome was assessed at 24 months. Eighty-four infants completed neurodevelopmental follow-up. 18 of newborns died during the neonatal period. Among the survivors, 64%, 21% and 15% had respectively normal, moderate and severe outcomes. The first EEG before hypothermia do not correlated with the neurodevelopmental outcome. On the other hand, The EEG characteristics between 36 and 60 h of life, correlated strongly with the outcome. Normal or mildly abnormal EEG (minor abnormalities or discontinuous tracing type A) after the first 48 h had 95% positive predictive value EEG for normal or moderate impairment at 2 years (negative predictive value 77%, specificity 91%). Severe EEG abnormalities (discontinuous tracing type B, paroxysmal or inactive tracings) within the first 48 h had respectively 96% and 76% negative and positive value for poor outcomes (severe outcome or death) (sensitivity 91% and specificity 89%).

Introduction High Density electroencephalography (HD EEG) is the reference non-invasive technique to investigate the dynamics of neuronal networks in Benign Epilepsy with Centro-Temporal Spikes (BECTS). Analysis of local dynamic changes surrounding Interictal Epileptic Spikes (IES) might improve our knowledge of the mechanisms that propel neurons to the hypersynchronization of IES in BECTS. Transient distant changes in the dynamics of neurons populations may also interact with neuronal networks involved in various functions that are impaired in BECTS patients. Methods HD EEG (64 electrodes) of eight well characterized BECTS patients (8 males; mean age: 7.2 years, range: 5–9 years) were analyzed. Unilateral IES were selected in 6 patients. They were bilateral and independent in 2 other patients. This resulted in a total of 10 groups of IES. Time–frequency analysis was performed on HD EEG epochs around the peak of the IES (±1000 ms), including phase-locked and non-phase-locked activities to the IES. The time frequency analyses were calculated for the frequencies between 4 and 200 Hz Results Time–frequency analysis revealed two patterns of dysregulation of the synchronization between neuronal networks preceding and following hypersynchronization of interictal spikes (±400 ms) in the epileptogenic zone. Dysregulation consists of either desynchronization (n = 6) or oscillating synchronization (n = 4) (4–50 Hz) surrounding the IES. The 2 patients with bilateral IES exhibited only local desynchronization whatever the IES considered. Distant desynchronization in low frequencies within the same window occurs simultaneously in bilateral frontal, temporal and occipital areas (n = 7). Conclusion Using time–frequency analysis of HD EEG data in a well-defined population of BECTS, we demonstrated repeated complex changes in the dynamics of neuronal networks not only during, but also, before and after the IES. In the epileptogenic zone, our results found more complex reorganization of the local network than initially thought. In line with previous results obtained at a microscopic or macroscopic level, these changes suggested the variability strategies of neuronal assemblies to raise IES. Distant changes from the epileptogenic zone in desynchronization observed in the same time window suggested interactions between larger embedded networks and opened new avenues about their possible role in the underlying mechanism leading to cognitive deficits.

Objective Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. Methods We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrared spectroscopy in an intentionally heterogeneous population of six children with spasms in series. Results Regardless of the etiology, spasms were accompanied by two phases of hemodynamic changes; an initial change in the cerebral blood volume (simultaneously with each spasm) followed by a neurovascular coupling in all children except for the one with a large porencephalic cyst. Discussion Changes in cerebral blood volume, like the neurovascular coupling, occurred over frontal areas in all patients regardless of any brain damage suggesting a diffuse hemodynamic cortical response. Significance The simultaneous motor activation and changes in cerebral blood volume might result from the involvement of the brainstem. The inconstant neurovascular coupling phase suggests a diffuse activation of the brain likely resulting too from the brainstem involvement that might trigger diffuse changes in cortical excitability.