Considerations for long-range EEG monitoring

Long-range EEG monitoring is not necessary in the routine work of clinical epilepsy diagnosis and treatment, but is essential when the diagnosis is in doubt and for preoperative localization assessment. However, long-range EEG monitoring differs from routine EEG examinations in that the proper placement of electrodes and the risk of seizures due to the prolonged duration of the monitoring should be paid close attention to during the monitoring process. These tasks are usually shared by doctors and technicians, but in most of the EEG rooms in China, this task is undertaken by nurses and technicians. In our long-term clinical work, we have summarized the matters that should be paid attention to during the long-distance EEG monitoring: 1. Electrode placement: Because the electrodes are easy to fall off, most of the laboratories require that the electrodes be fixed with sponge adhesive and then wrapped with an elastic bandage during the long-distance EEG monitoring. The adhesive is so strong that it must be eluted with acetone solution at the end of the monitoring. Sometimes when temporal lobe epilepsy is suspected, a soft-wire-like buried pterion electrode is often used during monitoring. Such electrodes are prone to being pulled and dislodged from the puncture point inadvertently or during a seizure, affecting the accuracy of the monitoring results. Therefore, it is important to explain that the technician and the patient need to handle the electrode connection wire carefully on the one hand, and carefully secure the exposed electrode wire firmly with gauze, cotton balls, and tape on the other. It is better to fix the electrode wires with tape at several turning points separately so as not to tear off the electrodes in one pull. 2, the administration of hypnotic drugs: in the routine EEG examination often requires about half an hour of sleep EEG monitoring, the purpose is to increase the EEG detection rate of epileptic discharges during sleep. It is customary to give patients chloral hydrate or isoamylbarbital for rapid sleep induction. However, this is not necessary during long-range EEG monitoring because there is enough time to wait and the patient is better off sleeping naturally. All the laboratory needs is to provide a quiet and comfortable environment. 3. Use of video: The diagnosis of some of the monitored patients is still in doubt, so it is very important to clearly record the symptoms during the seizure. Sometimes the aura and EEG manifestations before the seizure are more important because of the different purposes of observation. This requires the recorder to observe carefully, and when the patient is found to have signs of a possible seizure, quickly remove the bedding on the patient to expose his/her limbs so as to record his/her seizure posture on video; at the same time, adjust the angle and focus of the camera to the optimal state. 4. Duration of long-range EEG monitoring: The duration of monitoring is different according to the purpose of EEG monitoring, which can be several days to a week. If the seizure is captured, the time can be longer until the purpose of monitoring is accomplished. However, it is also affected by the implantable electrodes, and too long a period increases the likelihood of infection. In the previous literature, it has been suggested that the detection rate of epileptic discharges in 4-hour EEG monitoring is equivalent to that of 24-hour monitoring. In our opinion: sleep can induce epileptiform discharges, the frequency of which is particularly pronounced in NREM stages 1 and 2, but less so in stages 3 and 4 and REM, and is more frequent in the first sleep cycle throughout the night. Therefore the monitoring process should include at least one full sleep cycle, the approximate duration of which is 90 minutes or more. If a seizure EEG is not required, then the monitoring task can be terminated by finding significant epileptiform discharges. This is when the technician is able to make a request to the physician to stop the EEG monitoring. 5.Preparation work before monitoring: Because the monitoring time is long and in a relatively restricted activity space. In some EEG laboratories with better conditions, patients can have a larger space to move around during monitoring, such as going to the bathroom. However, in most laboratories the patient is confined to moving within 1-2 meters of the examination bed. Therefore, patients are asked to empty their bowels and change into a set of loose clothes that can be unfastened from the chest before monitoring, rather than wearing a pullover, so as not to be able to remove it easily after sweating, which may affect the results of the EEG tracing. In addition, you should spend some time to communicate with the patient or family members, explaining the patient’s seizure and the whole monitoring process may be the case, which is very important for the completion of the monitoring task, but also will reduce unnecessary disputes. So keep in mind: do not ignore these few minutes of communication time, both sides will benefit. 6. Precautions during the monitoring process: During the monitoring, the patient can be given some necessary evoked tests to induce seizures, such as flash stimulation, hyperventilation, sleep deprivation, etc., in order to achieve the purpose of EEG monitoring in a short period of time. Record the duration of the seizure during the seizure; call their names to determine their state of consciousness; protect the patient and keep the airway open to avoid falling off the bed, biting the tongue and electrode dislodgement; notify the doctor in time, and ask if there is any further treatment. 7, the treatment after monitoring: the cloudy period of consciousness after the seizure can often be seen in clinical work, especially in multiple seizures, the patient can even appear mental disorders, especially in the longer seizure time and epilepsy persistence is more common. But often this symptom is often maintained for a short period of time, usually a few minutes or tens of minutes. Some patients recover after a nap. The mechanism of its occurrence is related to ischemia and hypoxia of the brain as well as cerebral edema, so it responds better to oxygenation and dehydration to lower cranial pressure treatment. In clinical practice, there have been cases of patients with prolonged psychiatric disorders after multiple episodes, although the severity of the episodes was not severe and they were treated in a timely manner. The reason for this may be related to a trigger mechanism, which is worth exploring further. After the EEG monitoring task is completed, the patient is escorted back to the general ward, and his/her condition is explained to the on-duty doctors and nurses; the technician has to organize the information in a timely manner, and time-stamp the video recordings so that the doctors can watch them repeatedly. The execution of the EEG long-term monitoring task depends on the mutual cooperation of the above links, which has a great relationship with the work experience of technicians and nursing staff. Understanding the entire workflow of monitoring is necessary for the successful completion of the task.