Sleep-epilepsy interactions in patients with intractable generalized tonic seizures and depth electrodes in the centro median thalamic nucleus
Sleep-epilepsy interactions were studied in ten patients with Lennox-Gastaut Syndrome (LGS) suffering intractable generalized tonic seizures associated with generalized ictal fast spikes and interictal slow spike-wave complexes, where electrodes were implanted in the centromedian thalamic nucleus (CM) as part of a neuroaugmentive procedure for seizure control. In these patients, continuous all night recordings according to International Guidelines were performed to quantitatively determine changes in sleep patterns produced by the epileptic condition and changes in ictal and interictal surface and CM EEG activities produced by sleep stages. LGS patients showed significantly longer wakefulness (W) and shorter slow wave sleep (SWS) II than normals. Patients with seizures during the night showed shorter latency and larger number of paradoxical sleep (PS) periods than those patients without seizures. Ictal and interictal spike-wave EEG activities appeared together in surface and CM regions during all sleep stages with a ratio SURFACE/CM almost equal to one and PS did not focalize ictal and interictal activities in thalamic or cortical regions. Occurrence and duration of "myoclonic" ictal EEG component and number of interictal spike-wave complexes were higher during SWSII while they were smaller during PS than during W.