 About 25 of patients with drug-resistant partial epilepsy who undergo long-term video-EEG monitoring develop at least one partial secondary generalized tonic-clonic seizure. However, these patients cannot be individualized a priori. Therefore, all adult patients with drug-resistant epilepsy who will undergo long-term video-EEG monitoring in one of the participating centres, will lack all exclusion criteria, and will give their written informed consent to participate to the study if they develop GTCS, will be included in the study. They will all benefit from continuous monitoring of pulse oximetry together with video, EEG, and respiration recordings, and will be equipped with a peripheral venous catheter throughout the video-EEG. The modalities of the video-EEG monitoring will be consistent with the current practices and similar across the 14 centres apart from the venous catheter which is not standard practice. 