Procedure
A pair of quadripolar Medtronic DBS electrodes were bilaterally and stereotaxically inserted into the anterior part of the thalamus during general anaesthesia. Contact lengths of the electrode are 1.5 mm, whereas intercontact spacing is 0.5 mm. Electrode diameter is 1.27 mm. Besides frontal transventricular and extraventricular trajectories, the posterior parietal extraventricular approaches were used in accordance with the decisions of the clinical-neurosurgical team. In accordance with the clinical protocol patients underwent a 48 hour, postsurgical video-EEG monitoring with externalized thalamic leads, that is thalamic LFP co-registered with scalp EEG/polygraphy. The first 48 hours were recorded without thalamic stimulation (DBS-off). One whole-night seizure-free records of the 48 hours DBS-off records were selected and analyzed in the present study.