Epilepsy does not always have foci. Theoretically, epilepsy is a group of clinical syndromes caused by abnormal brain discharges, and there must be an abnormality in the brain cells to cause a seizure, but the abnormality cannot always be detected with current tests. Epilepsy is divided into three categories according to its cause, which is related to whether or not the lesion can be detected: the first category, primary epilepsy, refers to epilepsy in which no abnormality can be detected with the current examination methods. The second category, symptomatic epilepsy, also known as secondary epilepsy, refers to epilepsy in which a definite intracranial lesion can be detected by current means or in which there is a definite history of intracranial injury. The third category, cryptogenic epilepsy, this type of epilepsy is not to find a clear lesion, but from the patient’s clinical manifestations of seizure form and belongs to the symptomatic epilepsy, we have to consider its source is hidden so called cryptogenic epilepsy.