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Electroencephalography (EEG) is a method that is used to study the state of the human brain and is based on recording its electrical activity. This examination allows you to detect the spread of pathological processes and signs of epilepsy.
The average duration of the procedure is about an hour, but it is highly informative, makes it possible to track functional changes in the brain, the dynamics of the disease, and evaluate the impact of ongoing therapy.
Since the procedure does not cause any pain or discomfort, EEG can be called one of the most accurate and most gentle methods of examining the brain.
EEG principle
The human brain is made up of millions of special cells called neurons. Each of them generates its own electrical impulse. Within individual parts of the brain, impulses must be coordinated. They can also make each other stronger or weaker. Their strength and amplitude are not stable and are constantly changing.
This is the bioelectrical activity of the brain. To register it, special electrodes are applied to the intact scalp, which will pick up vibrations, amplify them and record them in the form of special curves, the so-called waves. The latter, depending on their shape, frequency and amplitude, are divided into five types: α- (alpha), β- (beta), δ- (delta), θ- (theta) and μ- (mu) waves. Each of the waves reflects the work of a certain part of the brain and is named by the first letter of its Latin name.
Their registration in real time is the essence of encephalography.
Historical information
Hans Berger, a physiologist and psychiatrist from Germany, is considered one of the founders of the electroencephalography method. In 1924, using a device for measuring small currents called a galvanometer, he was the first to perform a procedure resembling an EEG recording.
Later, a special device called an encephalograph was created to conduct electroencephalography. To date, there are stationary encephalographs, which make it possible to conduct research exclusively in a special room, and portable ones, which are designed for long-term monitoring and can be moved.
It is noteworthy that initially the EEG was considered solely as a method to identify mental disorders in a person. Only with time did it become clear that the technique also made it possible to detect deviations not related to psychiatry.
Significance of the EEG
EEG is a highly informative diagnostic method that allows you to:
- assess the nature of brain dysfunction and how pronounced they are;
- determine the location of the pathological focus;
- clarify information obtained during other diagnostic procedures (for example, computed tomography);
- see how effective the therapy is;
- identify areas of the brain in which epileptic activity is present;
- evaluate the work of the brain in the periods between attacks;
- identify the causes of panic attacks and fainting;
- study the sleep-wake cycle.
It should be borne in mind that if a person has convulsive seizures, the study will be informative only if it is carried out after about a week.
Benefits of electroencephalography
Today, electroencephalography is widely used in neuropathological practice. It makes it possible to clarify a huge number of problematic situations that are associated with the diagnosis and differentiation of neurological diseases. One of the indisputable advantages of encephalography is the fact that it not only helps to identify certain problems, but also helps to distinguish true disorders from hysterical manifestations or simulations.
In addition, the procedure is not as expensive as an examination with a tomograph or other similar devices. EEG equipment is available in most hospitals.
The procedure does not have any negative impact on human health and condition. The patient is fully functional. It is possible to conduct a study even for patients in serious condition, children and adults of any age, since it does not cause deterioration, discomfort or pain.
Indications for the procedure
To date, electroencephalography is widely used in the practice of a neuropathologist to solve a number of problems.
An EEG is recommended:
- with prolonged insomnia and other sleep disorders, including sleep apnea, somnambulism and talking during sleep;
- with a convulsive attack;
- with diseases of the thyroid gland;
- with signs of developmental disorders in children or mental disorders in adults;
- after recent traumatic brain injury;
- with pathological changes in the vessels of the neck and head, brain tumors detected during ultrasound;
- with frequent migraines, complaints of regular dizziness, feeling of constant fatigue;
- with panic attacks, autism, Asperger’s syndrome, stuttering, nervous tics, delayed speech and mental development in children;
- with meningitis, encephalitis, after stroke and microstroke;
- after neurosurgical operations.
Противопоказания
It is noteworthy that there are no absolute contraindications for electroencephalography. In the event that a person suffers from convulsive attacks, he is diagnosed with coronary heart disease, hypertension, mental disorders, an anesthesiologist is always present during the diagnosis.
The procedure should be postponed if there are open wounds, traumatic injuries, postoperative sutures or any signs of an inflammatory process in the area where it is necessary to install the electrodes. Also, the study is not conducted for patients with SARS.
How to prepare for an EEG
It should be noted that there are no special restrictions that should precede the procedure. However, there are a number of rules that it is recommended to follow in order for the examination to be successful and informative.
First of all, inform your doctor if you are taking any medications. You may have to stop taking them for a while or change the dosage.
At least twelve hours before the procedure, and even better – a day, exclude from the diet foods that contain caffeine, carbonated drinks, chocolate and cocoa, as well as foods that contain them, foods with energy components, for example, taurine. You should also avoid products with a sedative effect.
Wash your hair before the procedure. It is not recommended to use additional styling products (oils, gels, balms, varnishes, etc.) as this may affect the quality of contact between the electrodes and the skin.
In the event that the main purpose of the procedure is to identify seizure activity, you need to sleep before the study.
In order for the result to be as reliable as possible, the patient should avoid stressful situations and refrain from driving for twelve hours before the procedure.
Eating is recommended two hours before the procedure.
In the event that the patient is prescribed EEG sleep monitoring, the night before should be sleepless. Immediately before the procedure, the subject will receive a special sedative drug that will enable him to fall asleep during the electroencephalography.
In the event that a child must undergo an examination, parents should first prepare him psychologically for manipulations, explaining that there will be no pain and discomfort. You can practice putting on a cap for the pool under the pretext of playing pilots or astronauts, teach your baby to breathe deeply, showing him how to do it, by personal example. On the eve of the procedure, the child should wash their hair without using any additional styling products. Before leaving the house, the baby should be fed and reassured. Just in case, parents are advised to bring delicious food and drink, a favorite toy that will help calm and distract the baby.
Please note that if the above rules are not followed, the EEG result may not be very accurate or informative. In this case, the procedure will have to be repeated.
Performing an EEG
Electroencephalography is performed in a special room that is completely isolated from light and sound. The patient sits in a chair or is asked to lie down on a couch. A special cap with electrodes is put on his head first. During the procedure, the patient is alone in the room, contact with the doctors is maintained using a camera and a microphone. If the diagnosis is carried out on a child, one of the parents remains in the office.
Before starting the procedure, the patient is asked to close and open their eyes several times to adjust the equipment. During the examination, the eyes must be closed. In the event that during the procedure the patient needs to change position or visit the restroom, he can inform the doctors about this, after which the diagnosis will be suspended.
It is extremely important that during the procedure the patient lies with his eyes closed and does not move. In the event that a person opens his eyes or moves, the doctor makes an appropriate note, since these actions must be taken into account when deciphering the electroencephalogram.
After the resting EEG is recorded, so-called “stress tests” are performed. Their goal is to test how the brain will react to situations that are stressful for it.
So, a hyperventilation test can be performed. The patient is asked to breathe rapidly and deeply for three minutes. Photostimulation with a stroboscopic light source can also be used. It blinks frequently, and this allows you to evaluate how the brain reacts to bright light.
Stress testing can provoke convulsions or an epileptic seizure. The doctors who conduct the study have the appropriate skills to provide emergency care to the patient if necessary.
After the study is completed, the doctor should remind the patient to resume taking medications that were canceled on the eve of the EEG.
The total duration of the procedure is from forty minutes to two hours.
Purpose of EEG video monitoring
One of the varieties of electroencephalography is EEG video monitoring. This is a long-term EEG recording, usually lasting for several hours, that can be taken during sleep. The duration of the procedure in each case is determined by the attending physician and the staff of the laboratory that conducts the examination.
EEG video monitoring is prescribed if a short standard procedure does not reveal pathologies, but they are present.
Also, this type of examination allows you to evaluate the EEG during wakefulness and sleep.
Many patients are interested in the question of whether it is mandatory to sleep during the study. The answer to this question cannot be unambiguous, because it depends on the specific situation. So, for example, if the reason for the examination is a tic that disturbs the patient during wakefulness, it is not necessary to sleep during the examination.
At the same time, EEG video monitoring during sleep sometimes helps to identify conditions that neither the patient nor his relatives may even be aware of.
A feature of this procedure is that it can be carried out not only during the day, but also at night. In the event that a sleep EEG is required, nocturnal monitoring is more rational. In the daytime, not everyone can fall asleep without problems.
At the same time, we should not forget that conducting many hours of the procedure in a completely isolated room can be extremely tiring for the patient, especially when it comes to a child. Most pathologies can be detected during a relatively short recording of a conventional EEG.
Also nighttime EEG video monitoring is much more expensive.
Conclusion of electroencephalography
The result of the EEG study is presented by printouts of the obtained graphs and a conclusion in which the specialist notes the presence and nature of violations. Sometimes the result is recorded on electronic media – this is appropriate if long-term EEG video monitoring is carried out. All printouts and conclusions, as well as charts, should be carried with you during the consultation with a neurologist.
In this case, the doctor must explain to the patient that the EEG result in itself is not yet a diagnosis. This is just one of the fragments that helps the doctor draw conclusions about the patient’s condition.