Abstracts

Because of the excellent therapeutic effect and high safety of deep brain stimulation (DBS) in certain neurologic disorders, its clinical application has been extended to the treatment of epilepsy. Therefore, the procedure of stimulation electrode implantation provides an opportunity for studying neurophysiology of deep brain structures. We investigated the ictal EEG activity of subthalamic nucleus (STN) in treatment of patient with refractory epilepsy by deep brain stimulation (DBS). Seven patients with refractory epilepsy underwent implantation of DBS leads into bilateral STN. In addition to the extension of STN leads as intracranial EEG electrodes, subdural strips were implanted to the corresponding cortical regions of epileptogenesis. To obtain ictal and interictal epileptiform discharges, prolonged video-EEG recording was performed before delivering electric impulses into the STN. In a patient, the intracranial EEG was co-registered with electromyography of muscles involved in the myoclonic seizures. Over 50 epileptic seizures including partial seizures, atypical absence seizures, myoclonic seizures, tonic seizures, tonic-clonic seizures, and unclassified seizures were recorded. Ictal EEG activities in the STN had fast alpha activity, rhythmic spiking, and quasi/periodic spike/polyspike-and-slow-wave complexes that were not different from cortical epileptic patterns. Where there were bilaterally synchronous and rhythmic spikes and spike/polyspike-and-slow-wave discharges in generalized seizures would be faithfully reflected at bilateral STN simultaneously with opposite polarity. Additionally, myoclonic bursting was present at the STN. The STN generates epileptic EEG activity. The STN participates in the network interactions between cortical and subcortical structures. Diverse seizure activities of the STN reflect the pathogenesis of epilepsy that should influence the outcome of STN DBS.