Some cranial diseases, such as brain tumors, cerebrovascular disease, and intracranial infections, can cause seizures, especially lesions of the cerebral cortex that often cause seizures; some patients with congenital central nervous system malformations are prone to seizures; viral infection damage to the brain during embryonic development, radiation exposure or other causes of embryonic dysplasia can cause seizures; fetal Birth injuries and hypoxia during delivery are also a major cause of epilepsy, and cranial trauma can also cause epilepsy. These epilepsies with obvious causes are called secondary epilepsies and can often be detected by cranial MRI or brain CT, which is necessary for patients suspected of having epilepsy. However, there are other patients in whom no abnormalities can be found on cranial MRI or CT and the cause of the epilepsy cannot be found. Most of these patients are younger and are classified as having primary epilepsy.