EEG is a graphical representation of the spontaneous, rhythmic electrical activity of a population of brain cells recorded through electrodes, using a sophisticated electronic instrument that amplifies the spontaneous bioelectricity of the brain through the scalp. Abnormal EEG is characterized by abnormalities in frequency, amplitude, waveform, distribution, symmetry, stability, and responsiveness of the basic rhythm; abnormalities in the amplitude, interrelationship between amplitudes, and distribution of the frequency bands; and the disappearance of physiological responses or the appearance of abnormal responses, or increased slow activity. In addition, some patients will also have related pathological waves, as follows: 1. Spike, spike, spike-slow integrated wave, spike-slow integrated wave, multiple spike-slow integrated wave: most common in epilepsy, but also seen in tumors, trauma, inflammation and degenerative diseases; 2. Triphasic wave: most common in metabolic encephalopathy, such as liver and kidney failure and various causes of hypoxia; 3. Flat wave: also known as isotonic wave, common in 3, flat waves: also known as isotonic waves, commonly found in patients with severe brain damage or deep coma caused by various reasons; 4, glove waves: seen in deep brain tumors, vascular lesions, Parkinson’s syndrome and psychosis, etc. EEG is an effective method to examine changes in brain function, but because changes in brain function are dynamic and variable, patients with clinical manifestations of brain dysfunction cannot be completely excluded from the existence of brain disease when no abnormality is found in one EEG examination, and EEG reexamination should be performed regularly to accurately detect the disease.