title: Does the Thalamo-Cortical Synchrony Play a Role in Seizure Termination?
abstract: The mechanisms underlying seizure termination are still unclear despite their therapeutic importance. We studied thalamo-cortical connectivity and synchrony in human mesial temporal lobe seizures in order to analyze their role in seizure termination. Twenty-two seizures from 10 patients with drug-resistant mesial temporal lobe epilepsy undergoing pre-surgical evaluation were analyzed using intracerebral recordings [stereoelectroencephalography (SEEG)]. We performed a measure of SEEG signal interdependencies (non-linear correlation), to estimate the functional connectivity between thalamus and cortical regions. Then, we derived synchronization indices, namely global, thalamic, mesio-temporal, and thalamo-mesio temporal index at the onset and the end of seizures. In addition, an estimation of thalamic "outputs and inputs" connectivity was proposed. Thalamus was consistently involved in the last phase of all analyzed seizures and thalamic synchronization index was significantly more elevated at the end of seizure than at the onset. The global synchronization index at the end of seizure negatively correlated with seizure duration (p = 0.045) and in the same way the thalamic synchronization index showed an inverse tendency with seizure duration. Six seizures out of twenty-two displayed a particular thalamo-cortical spike-and-wave pattern at the end. They were associated to higher values of all synchronization indices and outputs from thalamus (p = 0.0079). SWP seizures displayed a higher and sustained increase of cortical and thalamo-cortical synchronization with a stronger participation of thalamic outputs. We suggest that thalamo-cortical oscillations might contribute to seizure termination via modulation of cortical synchronization. In the subgroup of SWP seizures, thalamus may exert a control on temporal lobe structures by inducing a stable hypersynchronization that ultimately leads to seizure termination.
authors.affiliation: Service de Neurophysiologie Clinique, CHU Timone, Assistance Publique des Hôpitaux de Marseille , Marseille , France.
authors.forename: Elisa
authors.initials: E
authors.lastname: Evangelista
authors.affiliation: UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France.
authors.forename: Christian
authors.initials: C
authors.lastname: Bénar
authors.affiliation: Service de Neurophysiologie Clinique, CHU Timone, Assistance Publique des Hôpitaux de Marseille , Marseille , France ; UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bonini
authors.affiliation: UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France ; Service de Neurochirurgie Fonctionnelle et Stéréotaxie, Assistance Publique des Hôpitaux de Marseille , Marseille , France.
authors.forename: Romain
authors.initials: R
authors.lastname: Carron
authors.affiliation: UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Colombet
authors.affiliation: UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France ; Service de Neurochirurgie Fonctionnelle et Stéréotaxie, Assistance Publique des Hôpitaux de Marseille , Marseille , France.
authors.forename: Jean
authors.initials: J
authors.lastname: Régis
authors.affiliation: Service de Neurophysiologie Clinique, CHU Timone, Assistance Publique des Hôpitaux de Marseille , Marseille , France ; UMR1106, INSERM , Marseille , France ; Institut de Neurosciences des Systèmes Marseille, Aix Marseille Université , Marseille , France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bartolomei
keywords: focal seizures; intracerebral EEG; seizure termination; synchrony; thalamus