Multifocal epilepsy in children is associated with increased long-distance functional connectivity: An explorative EEG-fMRI study.

Objective: Multifocal epileptic activity is an unfavourable feature of a number of epileptic syndromes (Lennox-Gastaut syndrome, West syndrome, severe focal epilepsies) which suggests an overall vulnerability of the brain to pathological synchronization. However, the mechanisms of multifocal activity are insufficiently understood. This explorative study investigates whether pathological connectivity within brain areas of the default mode network as well as thalamus, brainstem and retrosplenial cortex may predispose individuals to multifocal epileptic activity.

EEG-fMRI in myoclonic astatic epilepsy (Doose syndrome).

Objective: To identify neuronal networks underlying generalized spike and wave discharges (GSW) in myoclonic astatic epilepsy (MAE).

Methods: Simultaneous EEG-fMRI recordings were performed in 13 children with MAE. Individual GSW-associated blood oxygenation level-dependent (BOLD) signal changes were analyzed in every patient.

EEG-fMRI in atypical benign partial epilepsy.

Atypical benign partial epilepsy (ABPE) is a subgroup among the idiopathic focal epilepsies of childhood. Aim of this study was to investigate neuronal networks underlying ABPE and compare the results with previous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) studies of related epilepsy syndromes. Ten patients with ABPE underwent simultaneous EEG-fMRI recording.

Variability of EEG-fMRI findings in patients with SCN1A-positive Dravet syndrome.

Purpose: Dravet syndrome (DS) or severe myoclonic epilepsy of infancy is an intractable epileptic encephalopathy of early childhood that is caused by a mutation in the SCN1A gene in most patients. The aim of this study was to identify a syndrome-specific epileptic network underlying interictal epileptiform discharges (IEDs) in patients with DS.

Methods: Ten patients with the diagnosis of DS associated with mutations in the SCN1A gene were investigated using simultaneous recording of electroencephalography and functional magnetic resonance imaging ((EEG-fMRI).

Improving sensitivity of EEG-fMRI studies in epilepsy: the role of sleep-specific activity.

Using simultaneous recordings of EEG and functional MRI (EEG-fMRI) in patients with focal epilepsy, recent studies have revealed insufficient sensitivity and a lack of correspondence between epileptic EEG foci and activation patterns in some patients. In this study of children with focal epilepsy, we explore whether sleep-specific activity (sleep spindles, k-complexes and vertex sharp waves) may increase the sensitivity of EEG-fMRI of interictal epileptiform discharges (IED). When considering the sleep-specific activity in a statistical model, it was possible to increase the statistical significance of the activated voxels inside of the expected source of the IED and to reduce the number of activated voxels outside of it.

Neuronal networks in children with continuous spikes and waves during slow sleep.

Epileptic encephalopathy with continuous spikes and waves during slow sleep is an age-related disorder characterized by the presence of interictal epileptiform discharges during at least >85% of sleep and cognitive deficits associated with this electroencephalography pattern. The pathophysiological mechanisms of continuous spikes and waves during slow sleep and neuropsychological deficits associated with this condition are still poorly understood. Here, we investigated the haemodynamic changes associated with epileptic activity using simultaneous acquisitions of electroencephalography and functional magnetic resonance imaging in 12 children with symptomatic and cryptogenic continuous spikes and waves during slow sleep.

Non-REM sleep influences results of fMRI studies in epilepsy.

Although negative blood oxygen level-dependent (BOLD) signal changes are very frequent findings in neuroimaging studies of neuronal networks underlying interictal epileptiform discharges (IEDs), the nature of negative BOLD effects in epilepsy remains unclear. To investigate the influence of sleep on BOLD responses to internal activity such as IED, hemodynamic changes associated with IED were analysed in sleep stages 1 and 2 in four children with focal epilepsies who underwent simultaneous EEG-fMRI recordings. There were significantly more voxels with negative BOLD responses and better fit of the expected with the real course of BOLD signal for the negative BOLD effect in sleep stage 2 compared to stage 1.

Different neuronal networks are associated with spikes and slow activity in hypsarrhythmia.

Purpose: West syndrome is a severe epileptic encephalopathy of infancy characterized by a poor developmental outcome and hypsarrhythmia. The pathogenesis of hypsarrhythmia is insufficiently understood.

Methods: We investigated eight patients with infantile spasms and hypsarrhythmia (group I) and 8 children with complex partial seizures (group II) using simultaneous recordings of electroencephalogram (EEG) and functional MRI.