Many patients have a concern about having an EEG: can abnormal discharges be captured when they are not having a seizure? The answer is yes: yes. Epilepsy is a chronic disease with recurrent seizures. During the interictal period, there are abnormal discharges in the brain tissue, which are usually scattered and do not cause clinical seizures. When these discharges gradually intensify and accumulate to a certain level, they will cause clinical seizures. Most patients with epilepsy obtain an interictal EEG when they have an outpatient EEG. Because outpatient EEGs are short (usually 1 hour) and seizures usually occur several times a month, it is difficult to catch interictal EEGs. For medical treatment, an interictal EEG is sufficient. For surgical treatment, seizure EEG needs to be captured in order to localize the epileptic focus. Therefore, a long-range video EEG with continuous EEG testing is required.