OBJECTIVE: In this article we describe the course of synchronization between different EEG channels during nocturnal seizures in one patient with nocturnal frontal lobe epilepsy (NFLE).
METHODS: The functional interactions between the different EEG channels during the nocturnal seizures were analyzed by means of the so-called synchronization likelihood (SL). SL is a measure of the dynamical interdependencies between a time series (EEG channel) and one or more other time series. In contrast to coherence, SL measures linear as well as non-linear interdependencies and it can do so as a function of time, making it suitable for non-stationary time series.
RESULTS: The main result of our single-patient study is the demonstration of a significant hyper-synchronization during NFLE seizures in the 8-12 Hz band which seems to be stopped by an increase in synchronization in the 0.5-4 Hz band, towards the end of each ictal episode.
CONCLUSIONS: We suggest that a self-inhibiting complex mechanism might be responsible for the termination of ictal episodes which might take place at the level of the cortical layers and might involve mainly pyramidal neurons.
SIGNIFICANCE: This study shows that advanced EEG analysis methods can help the current understanding of ictal manifestations of NFLE.