An EEG is generally better the sooner the better for patients after a convulsion. Convulsion is an episodic disease that causes involuntary twitching or strong contraction of the whole body or localized groups of skeletal muscles, and is generally believed to be caused by abnormal discharges of motor neurons in the brain. The main purpose of an EEG in patients with convulsions is to find out whether there are abnormal discharges in the brain, so as to make a diagnosis and differential diagnosis. It is best to do an EEG immediately after the convulsion, as the excitability of neurons is still relatively high after the convulsion, and the probability of abnormal brain discharges appearing on the EEG is relatively high. However, in the interictal period after the end of the convulsion, about half of the patients with epilepsy will have a normal EEG. Therefore, a normal EEG in a patient with convulsions cannot exclude the possibility of abnormal brain discharges. Patients should seek medical attention as soon as possible after the convulsions to clarify the cause of the disease and treat it under the guidance of a doctor.