When a patient with epilepsy is seen, the doctor will diagnose the patient as having ‘primary epilepsy’ or ‘secondary epilepsy’ in the medical record. What is the basis for this diagnosis? Although epilepsy is a chronic brain disease, there are many complex causes. Some causes are very clear, such as brain tumors, traumatic brain injury, stroke, brain dysplasia and intracranial infections, and other central nervous system disorders can cause seizures secondary to epilepsy, so these types of epilepsy are called secondary epilepsy. However, there is a significant number of patients with epilepsy for whom the cause of their seizures cannot be found with current tests, and therefore are referred to as ‘primary epilepsy’. However, it is now thought that some of these may be due to genetic and genetic mutations, while others may have hidden causes, which will eventually be identified and discovered as medical tests continue to develop. For example, in some patients with focal cortical dysplasia, the lesion can only be detected by MRI with special imaging. In general, primary epilepsy is more common in children, while secondary epilepsy is more common in adults and older patients.