A patient visiting a hospital will without exception have an EEG done, if not more than once. There are various types of EEG, what is the difference? Ordinary scalp EEG: Usually takes about half an hour or so and is mainly used to observe the electrical characteristics of the brain during the interictal period. Dynamic EEG: also known as EEG holter. the subject wears it for use in the daily life environment, completes a 24-hour recording of all EEG activity, followed by computerized processing of the recorded data. the advantage is that the patient can move about on a daily basis, and the disadvantage is that there is no video footage. Mostly used to rule out the diagnosis of epilepsy. Long-range video EEG: In addition to observing the interictal EEG features, the patient’s sleep EEG features can be observed, and sometimes the patient’s clinical seizures can be captured, which is important for clarifying the type of epilepsy, guiding the use of medication, and preoperative evaluation. Usually 4-24 hours. Mostly used to clarify seizure type and preoperative evaluation. Seizure catching continuous EEG: Long-range video EEG is recorded continuously without interruption until the patient has 2-3 or even more typical clinical seizures. The monitoring time is variable depending on the patient’s usual seizure frequency and medication intake; some can be done in one day, while others need several days or even tens of days of continuous video EEG monitoring. It is mostly used for preoperative localization analysis in patients with intractable epilepsy. Intracranial EEG: Craniotomy or transcranial microvascular surgery, electrodes are placed into the skull before EEG recording. It is mostly used for localization of epileptic foci in patients with intractable epilepsy who cannot be accurately localized by non-invasive methods. Intracranial electrodes are less disturbed, rich in EEG signals, and have good localization effect.