Clinical applications of EEG in epileptology: (a) for the diagnosis and differential diagnosis of epilepsy. There are two prerequisites for the diagnosis of epilepsy: (1) clinical symptoms of seizures caused by brain dysfunction; (2) epileptiform discharges detected by EEG. (b) For the typing of epilepsy. Different types of epilepsy have different EEG manifestations. (3) To assist in the rational clinical selection of antiepileptic drugs and to judge the reduction and discontinuation of antiepileptic drugs. (iv) To determine prognosis. (v) To assist in the surgical treatment of epilepsy. The key to surgical treatment of epilepsy is the selection of indications and the accurate localization of the epileptogenic focus. Preoperative EEG monitoring is to understand the origin and diffusion mode of seizures, to assist in the accurate localization of epileptogenic foci, and to provide reference for the selection of surgical modality. Zhang Hua, Department of Neurosurgery, Tangdu Hospital, Fourth Military Medical University Video EEG (V-EEG) is a combination of an EEG monitoring system and a video recording device to record the clinical manifestations of the patient’s seizures and EEG simultaneously. The doctor can carefully observe the clinical manifestations of the patient’s seizures according to the video data and analyze them against the simultaneous EEG recordings, which can more accurately determine the type of seizures and the possible starting site, as well as accurately It can also improve the accuracy and reliability of EEG monitoring results by accurately grasping the patient’s activity status and corresponding EEG changes in each time period, timely detecting and eliminating various interference artifacts and electrode faults. The following is a summary of questions related to epilepsy EEG monitoring: 1. Must video EEG be performed before epilepsy surgical treatment? The most important factor in deciding on surgical treatment for a patient with intractable, focal epilepsy is the consistency of the results of different assessment protocols for the epileptogenic source area after the pre-surgical treatment evaluation of that patient. These evaluation protocols include: seizure symptomatology, interictal EEG, interictal EEG, neuroimaging, and all neuropsychological testing associated with the lesion. Long-time video electroencephalography (V-EEG) monitoring provides the patient’s clinical seizure manifestations, interictal EEG and ictal EEG simultaneously, which has a pivotal role in epilepsy surgical treatment and is an indispensable part of the preoperative examination for epilepsy surgery. 2. Is there any damage to human body when EEG is performed? As a non-invasive examination method, we place electrodes on the human scalp, not to energize the head, but to direct the spontaneous and rhythmic weak electrical signals of brain cell groups through electrodes and wires, which are amplified, filtered and processed by EEG machine and reflected on the computer screen to get different graphics of EEG activities, so as to make a judgment on the patient’s brain condition. Therefore, if we know the working principle and examination mechanism of EEG, we can conclude that EEG examination not only has no damage to human body, but also is an indispensable examination means for understanding patients’ condition, timely treatment and health recovery. 3.Why do I need to do video EEG monitoring when I have already done CT or MRI examination? CT or MRI is an imaging test, which can only distinguish the abnormalities in brain structure. Video electroencephalography (V-EEG) monitoring can identify functional abnormalities in the brain and can directly detect epileptic foci. Epileptic foci detected by EEG sometimes need to be confirmed by CT or MRI for accurate localization. Therefore, one of the two tests is indispensable for the localization of epileptic foci. 4.What are the preparations to be done before video electroencephalogram (V-EEG) monitoring? (1) The doctor should inform the patient of the video EEG examination, inform him/her of the purpose of the examination and the time of the machine, explain the examination requirements clearly to the patient, eliminate the patient’s concerns, so that the patient can fully understand and cooperate with the examination, and provide relevant medical history information. (2) Patients should clean their heads before the examination, and cut their hair short if necessary. No hair oil, hair wax, mousse or other substances should be applied. (3) Patients need to be accompanied by relatives after entering the video monitoring ward to help the patient to alert and observe, record and describe the patient’s performance during seizures and relevant information requested by the physician. (4) Patients and accompanying persons should turn off their cell phones, computers and video games after entering the video monitoring ward to avoid electromagnetic wave interference affecting the accuracy of the EEG examination. (5) For patients who are too young or unable to cooperate, give chloral hydrate orally or by enema if necessary. 5.What are the precautions and requirements when doing video EEG (V-EEG) examination? (1) Patients must be supported by bedside guardrails during V-EEG monitoring to avoid accidental injury during seizures. (2) During the whole process of V-EEG monitoring, all patient activities should be controlled within the range of the camera lens and the electrode leads should be connected reliably to ensure the quality of V-EEG monitoring. (3) Do not play, make noise or fight in the monitoring room, and keep the room quiet and comfortable. (4) Chaperones should not sleep with the patient. When the patient has a seizure, the chaperone should immediately ring the bell to alert the patient, do not press or pull the patient, do not block the camera lens, and lift the patient’s cover to facilitate observation of the patient’s performance during the seizure and pay attention to the patient’s safety. Record the patient’s condition and time during the seizure in detail and in a timely manner. (5) When the patient has a seizure, the nurse should immediately be in place to observe the situation and lift the covers to note whether the camera is blocked, closely observe the seizure and clinical manifestations, observe the patient’s consciousness, while turning the patient’s head to the side and removing the pillow to prevent the patient’s airway from being obstructed. Make relevant records in a timely manner. (6) The patient should be given oxygen immediately after the seizure, and in case of critical condition, the physician should be notified promptly for treatment. (7) The EEG monitoring personnel should frequently inspect the monitoring ward to keep abreast of the patient’s seizure and check the connection status of the electrode leads. (8) The EEG monitor should monitor the patient and the records continuously, closely and directly so that seizure events and technical failures in the EEG records can be identified quickly. The resulting valid and detailed test results will be important for the diagnosis of epilepsy and the localization of the epileptogenic zone. 6.How long does video EEG (V-EEG) monitoring need to be done before I can get off the machine? One of the most important means to improve the positive diagnostic rate of EEG is to extend the recording time. Some patients with epilepsy have seizures only at night; some patients have seizures and abnormal EEG manifestations mainly after waking up in the morning or just before waking up from sleep; and some patients only have epileptiform discharges during sleep. Infrequent interictal epileptiform discharges may be triggered by sleep. Therefore, in principle, video electroencephalography (V-EEG) monitoring is usually done for more than 24 hours and includes the sleep process. Patients evaluated preoperatively for epilepsy sometimes require longer monitoring in order to capture multiple habitual seizures. 7. Do I need to discontinue my antiepileptic medication during video EEG (V-EEG) monitoring? When performing V-EEG monitoring prior to epilepsy surgery, 2-3 or more habitual seizures must be recorded in order to provide a reference for preoperative localization. For patients with more frequent seizures, it is not necessary to stop the medication. For patients with sparse seizures and who cannot tolerate prolonged monitoring, the purpose of monitoring can be achieved by reducing or stopping the medication to induce seizures if necessary. However, medication reduction and discontinuation may change the original seizure form and epileptiform discharges, so in principle, the specific situation should follow medical advice. 8.Why do I need to do the video EEG monitoring for the second time after I have done it? As mentioned above, during the preoperative evaluation of epilepsy, the patient’s clinical seizure manifestations, interictal EEG and seizure EEG evaluation results are consistent in order to accurately locate the epileptic focus. However, in some patients with epilepsy, the clinical manifestations of seizures are complex, and there are various forms of interictal and ictal EEGs, so the information obtained in one visit is not sufficient to accurately localize the epileptogenic focus. Therefore, it is necessary to perform invasive intracranial electrode (video) EEG monitoring twice or even several times to achieve accurate localization of the epileptogenic focus. 9.Do I have to catch a seizure to perform V-EEG monitoring? Can I get off the machine without seizures? For patients undergoing preoperative epilepsy surgical evaluation, at least 2-3 or more habitual seizures should be captured in principle. For patients with very low seizure frequency who fail to capture seizures during prolonged video EEG (V-EEG) monitoring, if their clinical presentation is stereotyped and information such as interictal EEG and imaging can help to accurately localize them, they can be discharged without seizures. 10. Why continue monitoring when there have already been seizures during video EEG (V-EEG) monitoring? It is more clinically meaningful to capture the same seizures as usual, called habitual seizures. Only capturing at least 2-3 habitual seizures can be meaningful for localization of the epileptic focus.