Intraoperative electrical stimulation to localize the epileptogenic focus For patients in whom preoperative evaluation can localize the epileptogenic focus and surgical treatment is given, intraoperative cortical electroencephalography (ECoG) can further identify the epileptogenic focus, guide the extent of surgical resection, and assess the completeness of resection. However, in fact, we rarely use (ECoG) to localize the seizure initiation area. Because of the short intraoperative (ECoG) detection time, unclear meaning, and interference by anesthesia and other factors, it is difficult to record the washout EEG during seizures except for a few patients. In addition to intraoperative localization of functional brain areas, intraoperative electrical cortical stimulation can be used to induce discharges, clinical subencephalic seizures, aura seizures and clinical seizures, and thus be used as an aid to intraoperative localization of epileptogenic foci. Intraoperative electrical cortical stimulation can induce both habitual and non-habitual seizures. The significance of intraoperative electrical stimulation for localizing epileptogenic foci is still highly controversial. The distribution of intraoperative interictal spikes, the onset and duration of post-discharge, and the local brain tissue stimulation to induce the patient’s usual seizures are not always used to accurately localize the area of the epileptogenic focus. Stimulation intensity, stimulation pulse width, stimulation frequency, stimulation duration, and stimulation fraction may affect the outcome of electrical stimulation. Therefore, when intraoperative electrical stimulation is performed to locate the epileptogenic focus, various factors need to be taken into consideration to carefully analyze and locate the epileptogenic focus.