What is an EEG of the brain, indications and results. Everything about conducting an EEG (encephalogram) of the brain What is visible on the EEG

In order to avoid encountering such problems, it is necessary to carry out appropriate diagnosis in the presence of warning symptoms. High on the list of the most important procedures is electroencephalography, a fairly common type of brain research. Preparation for an EEG has a number of significant features that require special attention.

Brief introduction to EEG

This type of examination allows, through scanning, to track the activity of each part of the brain, neural impulses and, most importantly, the EEG clearly records the level of coordination of the actions of all components of the brain part (or the property of rhythm). If a person’s central nervous system is attacked by one or another ailment, diagnostics will reveal a disruption in the functioning of the organ.

Carrying out the test is not particularly difficult. The patient sits comfortably on an equipped couch in a reclining position. Certain points of the head are treated with a gel that ensures the conduction of impulses, and small electrodes are attached to the surface. When making a diagnosis, a person must relax his muscles and close his eyelids.

Next, a computer program is launched, which, using sensors, records brain activity and provides the necessary information in the form of several graphs. The procedure can last 1 hour, and in some cases the whole night under the close supervision of a doctor. The decrypted data will be received after a few days.

Despite the painlessness of EEG, a small child may become alarmed by what is happening, so the mother should be nearby and, if necessary, calm the child

Using EEG it is possible to detect:

• foci of epileptic activity;
• possible causes of fainting and panic attacks;
• various pathologies in the functioning of the brain and central nervous system as a whole;
• the effect of the prescribed complex of drugs on the body;
• violation of relevant functions, etc.

Indications and contraindications

It is worth noting a fairly wide range of anomalies, upon detection of which the doctor, with a high degree of probability, will prescribe his patient a referral for an electroencephalogram of the brain:

• sleep disturbances, such as sleepwalking and insomnia;
• presence of mechanical injuries: bruises, fractures;
• vascular diseases of the brain;
• tumor-like formations;
• mental disorders, neurosis, nervous tics;
• chronic fainting, uncontrollable panic attacks;
• coma state.

• the need to confirm brain death;
• epileptic seizures;
• various seizures;
• stroke;
• disruption of the endocrine system;
• autism, Down syndrome, cerebral palsy (CP);
• encephalitis and meningitis;
• vegetative-vascular dystonia (VSD);
• chronic headache of various types;
• delayed mental development or speech;
• disturbance of vascular circulation in the brain area, etc.

No special contraindications have been identified at the moment, but it is recommended to refrain from EEG for those who have various inflammations caused by infection, focal dermatosis, the presence of open wounds and other injuries in the head area, and the presence of surgically applied sutures that have not yet healed.

Traumatic head injuries are a contraindication to the procedure.

If the patient has pronounced neurological abnormalities in the form of a lack of control over the motor activity of his limbs, diagnosis should be carried out only under the close supervision of a qualified physician.

Procedure for preparing for an EEG

As mentioned earlier, before conducting an encephalogram, attention should be paid to the features of the preparatory stage. There is a classic list of rules, the observance of which will lead to the most accurate result of brain research.

Sometimes the patient is prescribed an EEG during the dream phase. In this case, a prerequisite is the absence of sleep for hours. The body should not be “sleepy” at the time of direct testing of the brain.

Cost of EEG

If you go to a private medical center, you will most likely have to pay about rubles for the session. The cost of research in government institutions is significantly lower - rubles.

An electroencephalogram of the brain can detect pathologies of the central nervous system or, conversely, exclude them. Despite the relative simplicity of diagnosis, you should not neglect the set of basic rules for preparing for an EEG. Remember: only correct adherence to each point will ensure a good examination result and, as a result, will indicate a clear direction to the vector of treatment therapy.

Comments

You can do an EEG at any clinic for a psychiatrist or only where he will refer you

EEG can be done in any suitable hospital

Electroencephalography

Electroencephalography (EEG) is a method for studying the functioning of the brain, based on recording electrical impulses emanating from its individual zones and regions. Such diagnostics have practically no contraindications; is fundamental for identifying epilepsy and some other brain pathologies. Electroencephalography (EEG) requires preliminary preparation. The result is deciphered jointly by the doctor conducting the study (neurophysiologist) and the neurologist treating the patient.

What it is

The brain consists of a huge number of neurons, each of which is a generator of its own electrical impulse. The impulses must be consistent within small areas of the brain; can strengthen or weaken each other. The strength and amplitude of these microcurrents are not stable, but must change.

This electrical (called bioelectrical) activity of the brain can be recorded using special metal electrodes placed on the intact scalp. They pick up brain vibrations, amplify them and record them as different vibrations. This is called electroencephalography, and for a person initiated into this “cipher” it is a graphical display of the brain’s work in real time.

Vibrations recorded on paper or displayed on a monitor are called waves. Depending on their shape, amplitude and frequency, experts divide them into alpha, beta, delta, theta, and mu waves.

Why do you need an EEG?

Diagnostics makes it possible to:

• assess the nature and degree of brain dysfunction;
• study the changes in sleep and wakefulness;
• determine the side and location of the pathological focus;
• clarify other types of diagnostics, for example, computed tomography, when a person has symptoms of neurological diseases, and other research methods do not reveal any structural defect;
• monitor the effectiveness of medications;
• find the areas of the brain where epileptic seizures begin;
• assess how the brain works between periods of seizures;
• determine the causes of crises, panic attacks, fainting.

The EEG does not “see” the injury itself or the site of development of the structural pathological process. And if a person has had an attack of convulsions or their equivalents, the study will be informative only a week or more after it.

Indications

Electroencephalography is widely used in the practice of neurologists. It not only helps to identify epilepsy, but when carried out with stimulation by light or sound, it allows one to distinguish a true visual or hearing disorder from a hysterical one, as well as from a simulation of such a condition.

EEG is indicated for:

• insomnia;
• sleep disorders (sleeping, sleep talking, sleep apnea);
• convulsive attacks;
• identified endocrine diseases;
• traumatic brain injuries;
• pathologies of the blood vessels of the head and neck (detected by ultrasound);
• encephalitis, meningitis;
• vegetative-vascular dystonia;
• after a stroke or mini-stroke;
• frequent headaches;
• dizziness;
• feeling of constant fatigue;
• after neurosurgery;
• more than one episode of fainting;
• panic attacks;
• diencephalic crises;
• any brain damage that developed before or after childbirth;
• stuttering;
• delayed speech development;
• autism;
• frequent awakenings during sleep.

Contraindications

There are no absolute contraindications for performing an EEG. If there are convulsive attacks, the person is sick with coronary heart disease, hypertension, or suffers from mental disorders, an anesthesiologist is present during the diagnosis (especially if functional tests are required).

Read also material about magnetic resonance imaging. What is it and what is it used for.

Preparation

It is not necessary to follow a specific diet, fast or cleanse the intestines before conducting an EEG, but the study is carried out after following several rules for preparing for it:

1. It is up to the doctor to decide whether or not to cancel the planned medication intake. You need to consult him about this in advance.
2. 12 hours before the examination, you need to stop taking products containing caffeine or energy drinks: coffee, chocolate, tea, cola, energy drinks.
3. Wash your hair, do not apply any products (spray, conditioners, masks, oils) to your hair after washing, as this will ensure insufficient contact of the electrodes with the scalp.
4. You need to eat a couple of hours before the procedure.
5. The EEG is carried out in a calm state, that is, you cannot be nervous or worried during the study.
6. If the doctor needs to detect seizure activity in the brain, he may ask the patient to sleep for a short amount of time before the test. In this case, you cannot get to the medical facility while driving.
7. Do not undergo testing if you have ARVI.
8. Do not perform the examination with your hair on your head.

The study is not contraindicated for children and pregnant women, but during these periods it is performed without functional tests.

If an EEG needs to be performed on a child, then first:

• parents need to explain to him the essence of the procedure, that it will not hurt;
• practice putting on a cap (for a pool, a sports one), presenting it in the form of a game of pilots, tank crews, divers;
• practice breathing deeply;
• wash your hair, do not braid your hair, remove your earrings;
• before leaving the child, feed and calm him down;
• take with you delicious food and drink, toys and books (to calm you down, distract you from the procedure).

Progress of the procedure

This type of diagnosis is usually carried out during the day, but sometimes a sleep EEG is more informative.

The patient goes into a special room, isolated from light and sound; a special cap with electrodes is put on his head, he sits in a comfortable chair or lies down on a couch. Only he remains in the room; communication with doctors is maintained using a microphone and camera.

Several times the patient is asked to close and open his eyes to evaluate the artifacts that appear on the encephalogram during blinking. During the diagnostic procedure, the eyes remain closed.

If at any point during the procedure a person needs to change position or go to the toilet, he informs the researcher. Diagnostics is paused.

Various tests can be used to diagnose hidden epilepsy:

1. With a flash of bright light;
2. With monotonous light switching on and off;
3. With hyperventilation, for which the patient is asked to breathe deeply several times (against this background, he may feel dizzy, but this will stop as soon as he breathes as usual);
4. With a loud sound;
5. With falling asleep - independently or with the help of a sedative.

In all these cases, a seizure or its equivalent may develop.

The procedure lasts from 45 minutes to 2 hours during the daytime. After its completion, the person can return to their usual activities.

EEG price in Moscow

EEG is carried out both in public medical institutions and in private clinics.

In budgetary treatment and preventive institutions, the cost of conducting research is rubles. Private medical centers in Moscow, for example, "NIARMEDIC", "SM-Clinic", "Dobromed", "Mental Health" and others offer this diagnosis for rubles.

The video describes the procedure:

How we save on supplements and vitamins: probiotics, vitamins intended for neurological diseases, etc. and we order on iHerb (use the link for a $5 discount). Delivery to Moscow is only 1-2 weeks. Many things are several times cheaper than buying them in a Russian store, and some goods cannot be found in Russia in principle.

Comments

After an encelography of my child’s brain, the conclusion said immaturity, I wanted to find out why this was happening and whether it would go away.

What is ECG, EMG, EEG?

An ECG is an electrocardiogram, a recording of the electrical signals of the heart. The fact that a potential difference arises in the heart when excited was shown back in 1856, during the era of Dubois-Reymond. An experiment proving this was carried out by Kölliker and Müller exactly according to Galvani’s recipe: the nerve leading to the frog’s leg was placed on an isolated heart, and this “living voltmeter” responded by shuddering the leg to each heart contraction.

With the advent of sensitive electrical measuring instruments, it became possible to detect electrical signals from the beating heart by applying electrodes not directly to the heart muscle, but to the skin.

In 1887, for the first time it was possible to register a human ECG in this way. This was done by the English scientist A. Waller using a capillary electrometer (The basis of this device was a thin capillary in which mercury bordered on sulfuric acid. When passing current through such a capillary, the surface tension at the border fluids changed and the meniscus shifted along the capillary.)

This device was inconvenient to use and the widespread use of electrocardiography began later, after the appearance in 1903 of a more advanced device - the Einthoven string galvanometer. (The operation of this device is based on the movement of a conductor with current in a magnetic field. The role of the conductor was played by a silver-plated quartz thread with a diameter of several micrometers, stretched tightly in a magnetic field. When current was passed through this string, it bent slightly. These deviations were observed using a microscope. The device had low inertia and made it possible to record fast electrical processes.)

After the appearance of this device, a number of laboratories began to study in detail how the ECG of a healthy heart differs from that of a heart with various diseases. For these works, V. Einthoven received the Nobel Prize in 1924, and the Soviet scientist A.F. Samoilov, who did a lot for the development of electrocardiography, received the Lenin Prize in 1930. As a result of the next step in the development of technology (the advent of electronic amplifiers and recorders), electrocardiographs began to be used in every major hospital.

When any nerve or muscle fiber is excited, the current in some parts of it flows through the membrane into the fiber, and in others it flows out. In this case, the current necessarily flows through the external environment surrounding the fiber and creates a potential difference in this environment. This makes it possible to record fiber excitation using extracellular electrodes without penetrating into the cell.

The heart is a fairly powerful muscle. Many fibers are synchronously excited in it, and a fairly strong current flows in the environment surrounding the heart, which even on the surface of the body creates potential differences of the order of 1 mV.

In order to learn more about the condition of the heart from an ECG, doctors record many curves between different points of the body. Understanding these curves requires a lot of experience. With the advent of computer technology, it has become possible to largely automate the process of “reading” an ECG. The computer compares the patient's ECG with samples stored in its memory and gives the doctor a probable diagnosis (or several possible diagnoses).

Now many other new approaches to ECG analysis have emerged. This seems very interesting. Based on data recorded from many points of the body and their changes over time, it is possible to calculate how the excitation wave moves through the heart and which parts of the heart have become inexcitable (for example, affected by a heart attack). These calculations are very labor-intensive, but they became possible with the advent of computers.

This approach to ECG analysis was developed by L.I. Titomir, an employee of the Institute for Information Transmission Problems of the USSR Academy of Sciences. Instead of many curves that are difficult to understand, the computer draws on the screen the heart and the distribution of excitation throughout its sections. You can directly see in which area of ​​the heart the excitation is slower, which parts of the heart are not excited at all, etc.

Heart potentials have been used in medicine not only for diagnostics, but also for controlling medical equipment. Imagine that a doctor needs to take x-rays of the heart at different phases of its cycle, i.e. at the moment of maximum contraction, maximum relaxation, etc. This may be necessary for some diseases. But how to catch the moment of greatest contraction? You have to take a lot of pictures in the hope that one of them will fall into the right phase.

And so the Soviet scientists V., S. Gurfinkel, V. B. Malkin and M. L. Tsetlin decided to turn on X-ray equipment from the ECG wave. This required a not very complex electronic device, which included filming with a given delay relative to the ECG wave. The solution to the problem, ingenious in itself, is especially interesting because it was one of the first (now numerous) devices in which the natural potentials of the body control certain artificial devices; This area of ​​technology is called biofeedback.

Skeletal muscles of the body also generate potentials that can be recorded from the surface of the skin. However, this requires more advanced equipment than for recording an ECG. Individual muscle fibers usually work asynchronously, their signals, superimposed on each other, are partially compensated, and as a result smaller potentials are obtained than in the case of an ECG.

The electrical activity of skeletal muscle is called an electromyogram - EMG. The potentials of human muscle fibers were first discovered by listening to them using a telephone by the Russian scientist N. E. Vvedensky back in 1882.

In 1907, the German scientist G. Pieper used a string galvanometer to objectively record them. However, this was a complex and time-consuming method. Only after the cathode oscilloscope and electronic technology appeared in 1923 did electromyography begin to develop rapidly. Now it is widely used in science, medicine, sports, and also for biocontrol.

One of the first great applications of EMG biofeedback is in the creation of prosthetics for people who have lost an arm. Such prostheses were created for the first time in our country.

What is an EEG?

This is an electroencephalogram, i.e. electrical activity of the brain, potential fluctuations created by the work of brain neurons and recorded directly from the surface of the head. Nerve cells, like muscle fibers, do not work simultaneously: when some of them create a positive potential on the surface of the skin, others create a negative one. The mutual compensation of potentials is even stronger here than in the case of EMG. As a result, the amplitude of the EEG is approximately one hundred times smaller than the ECG, so their registration requires more sensitive equipment.

EEG was first recorded by the Russian scientist V. V. Pravdich-Nemsky on dogs using a string galvanometer. He injected dogs with curare to prevent stronger muscle currents from interfering with the recording of brain currents.

In 1924, the German psychiatrist G. Berger began studying human EEG at the University of Jena. He described periodic oscillations of brain potentials with a frequency of about 10 Hz, which are called the alpha rhythm. He was the first to record an EEG “of a person during an epileptic attack and came to the conclusion that Galvani was right in suggesting that during epilepsy a region appears in the nervous system where the currents are especially strong (cells there are continuously excited at high frequency).

Since we were talking about very weak potentials recorded by a little-known doctor, Berger’s results did not attract attention for a long time; he himself published them only 5 years after his discovery. And only after they were confirmed by the famous English scientists Adrian and Matthews in 1930, they were marked with “. the seal of academic approval has been given,” in the words of G. Walter, an English scientist who worked on the clinical aspects of EEG in Goll’s laboratory. In this laboratory, methods were developed that made it possible to determine the location of a tumor or hemorrhage in the brain using EEG, just as they had previously learned to determine the location of a heart attack using ECG.

Later, in addition to the alpha rhythm, other brain rhythms were discovered, in particular rhythms associated with different types of sleep. There are a lot of biofeedback projects using EEG. For example, if a driver’s EEG is recorded all the time, then using a computer it is possible to determine the moment when he begins to doze off and wake him up. Unfortunately, all such projects are still difficult to implement, since the EEG amplitude is very small.

In addition to EEG - fluctuations in brain potential in the absence of special influences, there is also another form of brain potential - evoked potentials (EP).

Evoked potentials are electrical reactions that occur in response to a flash of light, sound, etc. Since many brain neurons respond almost simultaneously to a bright flash of light, evoked potentials usually have a much larger magnitude than the EEG. It is no coincidence that they were discovered much earlier than EEG (in 1875 by the Englishman Keton and independently in 1876 by the Russian researcher V. Ya. Danilevsky).

Evoked potentials can be used to solve interesting scientific problems. For example, after a flash of light, the response (RP) occurs first in the occipital region of the brain. From this we can conclude that it is in this area that light signals arrive.

When the skin is electrically stimulated, evoked potentials arise in the dark region of the brain.

When the skin of the hand is irritated, they appear in one place, the skin of the leg - in another. It is possible to map such responses, and this map shows that the surface of the skin gives a projection to the parietal region of the human cerebral cortex. It is interesting that during this design some proportions are violated, for example, the projection of the hand turns out to be disproportionately large. Yes, this is natural: the brain needs much more detailed information about the hand than, for example, about the back.

What is an ECG of the brain

One of the main methods used in diagnosing diseases of brain origin is the ECG method of the brain, in this case called EEG - electroencephalography. This study is based on recording electrical signals from the resulting discharges of brain cells, otherwise called biopotentials. This diagnostic study appeared relatively recently, like most modern methods actively used at present. The 20th century gave the world EEG, first establishing its use in dogs and then in humans.

The EEG technique helps the doctor assess the performance of the brain, its functionality. EEG is often more effective in diagnostic terms than CT and can show the smallest changes in brain tissue in the absence of such changes on a computed tomograph. In addition to its diagnostic value, EEG helps in differentiating diagnoses. For example, with the help of this research method it is possible to distinguish true epilepsy from other pathologies that imitate it, such as a panic attack, autonomic paroxysm, neuroses of various origins, and psychiatric pathologies.

The brain includes a large number of neurons - its cells, each of which creates its own electrical impulse, which characterizes the performance of the cell. Pulse shaping is a complex process in which signals are amplified or attenuated. An EEG creates a record of this bioelectrical brain activity through metal-based electrodes placed on a clean scalp. These electrodes register and record all brain impulses, and the doctor deciphers the resulting key, which is a reflection of the functional capabilities of the brain.

Conditions for conducting EEG

EEG is an absolutely safe method for the patient and does not have any harmful effects, since it is based on recording the biopotentials of one’s own body. To receive electrical impulses from the brain, the doctor places the necessary electrodes, which are moistened with a special substance, on the patient’s head area.

Even taking into account the high sensitivity of the device for recording EEG - electroencephalograph, for a more informative and high-quality recording of brain activity, the patient must fulfill some of the doctor’s requirements. In this study, a common request from doctors is:

• We request that the patient’s hair be free of gels, mousses, and hairspray, and that the patient’s hair be washed thoroughly. This necessity is required due to the creation of a mechanical obstacle to conducting an EEG, since when using cosmetics and excessive fatty secretions from unwashed hair, a film is formed and electrical impulses do not pass through it;
• The need to indicate information about the medications used for doctors, data on the tolerance of bright light flashes, existing diseases of the heart and vascular network, as well as the respiratory system;
• The day before the study, stop drinking alcohol, energy drinks, coffee drinks, and smoking. If for some reason their appointment took place, then the doctor should be informed;
• Lean eating, however, is not recommended to stop eating at all.

During the diagnostic procedure, the patient lies in a relaxed position, lying or sitting in a chair, with his eyes closed, since external and internal factors in the form of emotional fluctuations and environmental conditions can distort the EEG results. Registration of electrical impulses is carried out in two ways - under resting conditions and with functional tests. Recording in a calm state is a standard, ordinary study, lasting 10 - 30 minutes.

A stress test is necessary if it is necessary to diagnose the compensatory capabilities of the human brain when environmental conditions change. Most often, tests are performed such as opening and closing the eyes, tests using rhythmic stimulation of light and sound, deep breathing movements, falling asleep independently and after using sedatives.

Difficulties may arise when performing an EEG on children. It is difficult for them to explain what the method is, so most often during research the child is asked to play a game, imagining that a helmet with electrodes is the helmet of a superhero or stuntman. Fear in children before and during the procedure can provoke a distortion of the results obtained.

Indications and contraindications of the method

Indications for an EEG study may include the following conditions and suspicions:

• Epileptic seizures, in which it is possible not only to confirm their presence, but also to find the part of the brain responsible for the occurrence of seizures;
• Insomnia or frequent awakenings during sleep;
• Neoplasm of the brain;
• Stuttering and delayed speech development;
• Stroke, microstroke and pre-stroke condition;
• Cerebrovascular disorders of chronic origin;
• Cognitive disorders;
• Autonomic dysfunction;
• Repeated episodes of loss of consciousness;
• Traumatic brain injuries;
• Memory problems;
• Concentration disorders;
• Infectious diseases of the brain such as encephalitis and meningitis;
• Chronic uncaused fatigue;
• Repeated cases of heart rhythm disturbances.

In addition to the diagnostic value of the method in relation to specific diseases, EEG allows:

• Characterize brain performance and the presence of possible abnormalities;
• Assess the cyclicity of sleep and wakefulness;
• More accurately evaluate the results of other diagnostic types, in particular CT;
• Conduct an investigative examination of the effectiveness of the use of medicines;
• To assess the dynamics of brain function after brain surgery.

No contraindications to EEG diagnostics were found; there are only restrictions when conducting specific functional tests. Electroencephalography is a completely safe research method and is not associated with the use of radiation penetrating the human body or the use of foreign substances, therefore it is indicated for both children and adults at any age.

Conclusion EEG is an electroencephalogram, applied to paper in the form of a film or a stack of sheets and represents the depicted curves - waves reflecting brain activity, as well as the doctor’s decoding. The conclusion allows us to identify active areas of the brain in the form of certain waves and rhythms. They are designated by letters of the Greek alphabet. Most often, EEG is performed during the day, but sometimes the manipulation is carried out in the evening, for example, to assess sleep cycles.

In this case, the patient is examined in a specially designated room, isolated from light and sound vibrations. The patient remains alone in the room, the doctor maintains contact with him through installed cameras and a microphone.

EEG is carried out both in public institutions and in private ones. The average price of a study ranges from 400 to 1,500 rubles in budgetary organizations and from 1,500 to 3,500 thousand in private medical centers.

Electroencephalography (EEG): the essence of the examination, what it reveals, its conduct, results

For convenience, both doctors and patients replace the long word “electroencephalography” with an abbreviation and simply call this diagnostic method EEG. It should be noted here that some (probably to enhance the significance of the study) talk about EEG of the brain, but this is not entirely correct, since the Latinized version of the ancient Greek word “encephalon” is translated into Russian as “brain” and in itself is already part of the medical term is encephalography.

Electroencephalography or EEG is a method of studying the brain (BM) in order to identify foci of increased convulsive readiness of its cortex, which is typical for epilepsy (the main task), tumors, conditions after a stroke, structural and metabolic encephalopathies, sleep disorders and other diseases. Encephalography is based on recording the electrical activity of the brain (frequency, amplitude), and this is done using electrodes attached in different places on the surface of the head.

What kind of research is an EEG?

Periodically occurring convulsive seizures, occurring in most cases with complete loss of consciousness, are popularly called falling disease, which official medicine calls epilepsy.

The very first and main method for diagnosing this disease, which has served humanity for many decades (the first EEG recorded dates back to 1928), is encephalography (electroencephalography). Of course, the research apparatus (encephalograph) has now significantly changed and improved, its capabilities with the use of computer technology have expanded significantly. However, the essence of the diagnostic method remains the same.

Electrodes (sensors) are connected to the electroencephalograph, which are placed in the form of a cap on the surface of the subject’s head. These sensors are designed to capture the slightest electromagnetic bursts and transmit information about them to the main equipment (device, computer) for automatic processing and analysis. The encephalograph processes the received impulses, amplifies them and records them on paper in the form of a broken line, very reminiscent of an ECG.

Bioelectric activity of the brain is created mainly in the cortex with the participation of:

• The thalamus, which oversees and redistributes information;
• The ARS (activating reticular system), the nuclei of which, located in various parts of the brain (medulla oblongata and midbrain, pons, diencephalic system), receive signals from many pathways and transmit them to all parts of the cortex.

The electrodes read these signals and deliver them to the device, where recording occurs (graphic image - encephalogram). Processing and analyzing information are the tasks of computer software, which “knows” the norms of biological activity of the brain and the formation of biorhythms depending on age and a specific situation.

For example, routine EEG detects the formation of pathological rhythms during an attack or in the period between attacks; sleep EEG or nighttime EEG monitoring shows how the biopotentials of the brain change while immersed in the world of dreams.

Thus, electroencephalography shows the bioelectrical activity of the brain and the consistency of the activity of brain structures during wakefulness or sleep and answers the questions:

1. Are there any foci of increased convulsive readiness of the brain, and if they are, in what area are they located?
2. What stage is the disease at, how far has it gone or, conversely, has it begun to regress;
3. What effect does the chosen medicine have and is its dose calculated correctly;

Of course, even the most “smart” machine will not replace a specialist (usually a neurologist or neurophysiologist), who receives the right to decipher an encephalogram after undergoing special training.

Features of EEG in children

What can we say about kids, if some adults, having received a referral for an EEG, begin to ask what and how, because they doubt the safety of this procedure. Meanwhile, it actually cannot cause any harm to the child, but it can be really difficult to perform an EEG on a small patient. For babies under one year old, the bioelectrical activity of the brain is measured during sleep, before this they wash their hair, feed the baby and, without deviating from the usual schedule (sleep/wake), adjust the procedure to the child’s sleep.

But if for children under one year old it is enough to wait until they fall asleep, then a child from one to three years old (and some even older) still needs to be persuaded, therefore, up to 3 years of age, the study is carried out in a state of wakefulness only for calm and sociable children, giving preference in other cases to EEG sleep.

Preparations for visiting the appropriate office should begin several days in advance, turning the future trip into a game. You can try to interest the baby in a pleasant trip, where he can go with his mother and his favorite toy, come up with some other options (usually parents are more aware of how to convince the child to sit quietly, not move, cry or talk). Unfortunately, such restrictions are very difficult for young children to withstand, because they still cannot understand the seriousness of such an event. Well, in such cases the doctor is looking for an alternative...

Indications for performing daytime encephalography in a child in a state of sleep or nighttime EEG are:

• Identification of paroxysmal conditions of various origins - epileptic seizures, convulsive syndrome due to high body temperature (febrile convulsions), epileptiform seizures not associated with true epilepsy and differentiated from it;
• Monitoring the effectiveness of antiepileptic therapy with an established diagnosis of epilepsy;
• Diagnosis of hypoxic and ischemic lesions of the central nervous system (presence and severity);
• Determination of the severity of brain lesions for prognostic purposes;
• Study of the bioelectrical activity of the brain in young patients to study the stages of its maturation and the functional state of the central nervous system.

In addition, it is often suggested to do an EEG for vegetative-vascular dystonia with frequent fainting attacks and dizziness, with delayed acquisition of speech skills and stuttering. This method should not be neglected in other cases that require studying the reserves of the functional capabilities of the brain, because the procedure is both harmless and painless, but can provide maximum information for diagnosing a certain pathology. Electroencephalography is very useful if episodes of disturbances of consciousness occur, but their cause is not clear.

Different recording methods

Registration of bioelectric potentials of the brain is carried out in different ways, for example:

1. At the beginning of a diagnostic search that identifies the causes of paroxysmal conditions, a short-term (≈ 15 min) routine method of recording an encephalogram is used, which, to identify hidden disorders, involves the use of provocative tests - the patient is asked to breathe deeply (hyperventilation), open and close his eyes, or give light stimulation (photostimulation);
2. If a routine EEG does not provide the necessary information, then the doctor prescribes encephalography with deprivation (deprivation of sleep at night, completely or partially). To conduct such a study and obtain reliable results, a person is either not allowed to sleep at all, or is woken up 2-3 hours before the subject’s “biological alarm clock” rings;
3. Long-term recording of an EEG with registration of the bioelectrical activity of the brain cortex during “quiet hours” (sleep EEG) takes place if the doctor suspects that changes in the brain occur precisely while in “sleep mode”;
4. Experts consider nighttime EEG, which is recorded in a hospital setting, to be the most informative. The study begins while you are awake (before going to bed), continues when you fall asleep, covers the entire period of night sleep and ends after natural awakening. If necessary, registration of bioelectrical activity of the brain is supplemented by the application of supernumerary electrodes and the use of video recording equipment.

Long-term recording of electrical activity over several hours during sleep and recording of nighttime EEG is called EEG monitoring. Naturally, such methods require the use of additional equipment and material resources, as well as the patient’s stay in a hospital setting.

Time and equipment make up the price

In other cases, there is a need to measure the biopotentials of the brain at the time of an attack. Pursuing similar goals, the patient, as for conducting an overnight EEG, is sent to a hospital for hospitalization, where 24-hour EEG monitoring is carried out using audio and video equipment. Continuous EEG monitoring with video recording throughout the day makes it possible to verify the epileptic origin of paroxysmal memory disorders, isolated auras, as well as episodic psychomotor phenomena.

Electroencephalography is one of the most accessible methods for studying the brain. And for the price too. In Moscow, you can find this study for 1,500 rubles, 8,000 rubles (EEG sleep monitoring for 6 hours), and rubles (night EEG).

In other cities of Russia you can get by with a smaller amount, for example, in Bryansk the price starts from 1200 rubles, in Krasnoyarsk - from 1100 rubles, and in Astrakhan it starts from 800 rubles.

Of course, it is better to do an EEG in a specialized neurological clinic, where in doubtful cases there is the possibility of a collegial diagnosis (in such institutions, many specialists can encrypt the EEG), and also to consult a doctor immediately after the test or quickly resolve the issue regarding other methods of studying the brain.

About the main rhythms of electrical activity of the brain

When interpreting the results of the study, various factors are taken into account: the age of the subject, his general condition (the presence of tremor, weakness in the limbs, visual impairment, etc.), anticonvulsant therapy at the time of recording the bioelectric activity of the brain, the approximate time (date) of the last seizure and etc.

The electroencephalogram consists of various complex biorhythms emanating from the electrical activity of the brain at different periods of time, depending on specific situations.

When decoding the EEG, first of all, pay attention to the main rhythms and their characteristics:

• Alpha rhythm (frequency ranges from 9 to 13 Hz, oscillation amplitude ranges from 5 to 100 μV), which is present in almost all individuals who have no complaints about their health during the period of inactive wakefulness (relaxation during rest, relaxation, shallow meditation). As soon as a person opens his eyes and tries to visually imagine any picture, α-waves decrease and may disappear altogether if the functional activity of the brain continues to increase. When deciphering the EEG, the following parameters of the α-rhythm are important: amplitude (μV) over the left and right hemispheres, dominant frequency (Hz), dominance of certain leads (frontal, parietal, occipital, etc.), interhemispheric asymmetry (%). Depression of the α-rhythm is caused by anxiety, fear, and activation of autonomic nervous activity;
• The beta rhythm (frequency ranges from 13 to 39 Hz, the amplitude of oscillations is up to 20 μV) is not only our wakefulness mode, the beta rhythm is characteristic of active mental work. In a normal state, the expression of β-waves is very weak, their excess indicates an immediate reaction of the brain to stress;
• Theta rhythm (frequency - from 4 to 8 Hz, amplitude is within microvolts). These waves do not reflect a pathological change in consciousness, for example, a person is dozing, half asleep, in the stage of superficial sleep, he is already seeing some dreams, and then θ rhythms are detected. In a healthy person, falling into sleep is accompanied by the appearance of a significant number of θ rhythms. An increase in the theta rhythm is observed during prolonged psycho-emotional stress, mental disorders, twilight states characteristic of some neurological diseases, asthenic syndrome, and concussion;
• The delta rhythm (frequency ranges from 0.3 to 4 Hz, amplitude from 20 to 200 μV) is characteristic of deep sleep (natural falling asleep and artificially created sleep - anesthesia). With various neurological pathologies, an increase in the δ wave is observed;

In addition, other electrical oscillations occur in the cerebral cortex: gamma rhythms reaching high frequencies (up to 100 Hz), kappa rhythms formed in the temporal leads during active mental activity, mu rhythms associated with mental stress. These waves are not particularly interesting from a diagnostic point of view, since they arise under significant mental stress and intense “work of thought”, requiring high concentration of attention. An electroencephalogram, as is known, is recorded, although during wakefulness, but in a calm state, and in some cases, overnight EEG or sleep EEG monitoring is even prescribed.

Video: alpha and beta rhythms on EEG

EEG interpretation

main EEG leads and their designations

A bad or good EEG can only be judged after the final interpretation of the study results. Thus, we will talk about a good EEG if, during the waking period, the following were recorded on the encephalogram tape:

• In the occipital-parietal leads - sinusoidal α-waves with an oscillation frequency ranging from 8 to 12 Hz and an amplitude of 50 μV;
• In the frontal areas - β-rhythms with an oscillation frequency greater than 12 Hz and an amplitude not exceeding 20 μV. In some cases, β-waves alternate with θ-rhythms with a frequency of 4 to 7 Hz and this is also considered normal.

It should be noted that individual waves are not specific to any particular pathology. An example is epileptiform sharp waves, which under some circumstances can appear in healthy people who do not suffer from epilepsy. Conversely, peak-wave complexes (frequency 3 Hz) clearly indicate epilepsy with petit mal seizures, and sharp waves (frequency 1 Hz) indicate a progressive degenerative disease of the brain - Creutzfeldt-Jakob disease, therefore these waves are decoding is considered an important diagnostic feature.

In the period between attacks, epilepsy may not be noticed, since the peaks and sharp waves characteristic of this disease are not observed in all patients who show all the clinical symptoms of the pathology at the time of a convulsive seizure. Moreover, paroxysmal manifestations in other cases can be recorded in absolutely healthy people who do not have any signs or prerequisites for the development of a convulsive syndrome.

In connection with the above, having conducted a single study and not finding epileptic activity on the background EEG (“good EEG”), it is impossible to completely exclude epilepsy based on the results of one test if clinical signs of the disease occur. It is necessary to further examine the patient for this unpleasant disease using other methods.

Recording an EEG during a seizure in a patient with epilepsy may provide the following options:

1. Frequent electrical discharges of high amplitude, which indicate that the peak of the attack has occurred, slowing down of activity - the attack has entered the attenuation phase;
2. Focal epiactivity (it indicates the location of the focus of convulsive readiness and the presence of partial seizures - we will have to look for the cause of the focal lesion of the brain);
3. Manifestations of diffuse changes (registration of paroxysmal discharges and peak-wave) - such indicators indicate that the attack is generalized.

If the origin of the brain lesion is established, and diffuse changes are recorded on the EEG, then the diagnostic value of this study, although not so significant, still makes it possible to find a particular disease that is far from epilepsy:

• Meningitis, encephalitis (especially caused by herpetic infection) - on the EEG: periodic formation of epileptiform discharges;
• Metabolic encephalopathy - on the encephalogram: the presence of “triphasic” waves or diffuse slowdowns in rhythm and bursts of symmetrical slow activity in the frontal areas.

Diffuse changes in the encephalogram can be recorded in patients who have suffered a brain injury or concussion, which is understandable - with severe head injuries, the entire brain suffers. However, there is another option: diffuse changes are found in people who do not have any complaints and consider themselves absolutely healthy. This also happens, and if there are no clinical manifestations of pathology, then there is no cause for concern either. Perhaps, at the next examination, the EEG recording will reflect complete normality.

In what cases does EEG help make a diagnosis?

Electroencephalography, revealing the functionality and reserves of the central nervous system, has become the standard for brain research; doctors consider its implementation advisable in many cases and for various conditions:

1. To assess the degree of functional immaturity of the brain in young patients (in a child under one year old, the study is always carried out during sleep, in older children - depending on the situation);
2. For various sleep disorders (insomnia, drowsiness, frequent awakenings at night, etc.);
3. In the presence of convulsions and epileptic attacks;
4. To confirm or exclude complications of inflammatory processes caused by neuroinfection;
5. For vascular lesions of the brain;
6. After a TBI (brain contusion, concussion) - the EEG shows the depth of the GM’s suffering;
7. To assess the severity of the effects of exposure to neurotoxic poisons;
8. In case of development of an oncological process affecting the central nervous system;
9. For mental disorders of various kinds;
10. EEG monitoring is carried out when assessing the effectiveness of anticonvulsant therapy and selecting optimal dosages of medications;
11. The reason for doing an EEG may be signs of dysfunction of brain structures in children and suspicion of degenerative changes in the nervous tissue of the brain in older people (dementia, Parkinson's disease, Alzheimer's disease);
12. Patients in a coma need to have their brain assessed;
13. In some cases, the study requires surgical operations (determining the depth of anesthesia);
14. Encephalography will help to recognize how far neuropsychic disorders have gone in hepatic cellular failure (hepatic encephalopathy), as well as in other forms of metabolic encephalopathies (renal, hypoxic);
15. All drivers (future and current), when undergoing a medical examination to obtain/replace a license, are asked to undergo an EEG for a certificate provided by the traffic police. The examination is easy to use and easily identifies those who are completely unfit to drive vehicles, which is why it was adopted;
16. Electroencephalography is prescribed to conscripts who have a history of convulsive syndrome (based on medical card data) or in case of complaints of attacks with loss of consciousness accompanied by convulsions;
17. In some cases, a study such as EEG is used to ascertain the death of a significant part of the nerve cells, that is, brain death (we are talking about situations when they say that “a person has most likely turned into a plant”).

Video: EEG and detection of epilepsy

The study does not require special preparation

An EEG does not require any special preparation, but some patients are openly afraid of the upcoming procedure. It’s no joke - sensors with wires are placed on the head, which read “everything that is happening inside the skull” and transmit the full amount of information to the “smart” device (in fact, the electrodes record changes in the potential difference between two sensors in different leads). Adults are provided with symmetrical attachment to the surface of the head of 20 sensors + 1 unpaired one, which is superimposed on the parietal region; for a small child, 12 is enough.

Meanwhile, I would like to reassure particularly suspicious patients: the study is absolutely harmless, has no restrictions on frequency and age (at least several times a day and at any age - from the first days of life to old age, if circumstances so require).

The main preparation is to ensure the cleanliness of the hair, for which the day before the patient washes his hair with shampoo, rinses and dries well, but does not use any chemical hair styling products (gel, foam, varnish). Metal objects used for decoration (clips, earrings, hairpins, piercings) are also removed before an EEG is performed. Besides:

• For 2 days, they give up alcohol (strong and weak), do not drink drinks that stimulate the nervous system, and do not indulge in chocolate;
• Before the study, obtain medical advice regarding medications taken (sleeping pills, tranquilizers, anticonvulsants, etc.). It is possible that certain medications will have to be discontinued in consultation with the treating doctor, and if this cannot be done, then you should inform the doctor who will be involved in deciphering the encephalogram (a note on the referral form) so that he keeps these circumstances in mind and takes them into account when drawing up the conclusion.
• 2 hours before the examination, patients should not allow themselves a heavy meal and relaxation with a cigarette (such activities can distort the results);
• It is not recommended to do an EEG in the midst of an acute respiratory illness, as well as during coughing and nasal congestion, even if these signs do not relate to the acute process.

When all the rules of the preparatory stage are followed, certain points are taken into account, the patient is seated in a comfortable chair, the places where the surface of the head comes into contact with the electrodes are lubricated with gel, sensors are attached, a cap is put on or dispensed with, the device is turned on - the recording begins... Provocative tests are used as needed during time of registration of bioelectrical activity of the brain. As a rule, this need arises when routine methods do not provide adequate information, that is, when epilepsy is suspected. Techniques that provoke epileptic activity (deep breathing, opening and closing eyes, sleep, light irritation, sleep deprivation) activate the electrical activity of the brain cortex, electrodes pick up impulses sent by the cortex and transmit them to the main equipment for processing and recording.

In addition, if epilepsy is suspected (especially temporal epilepsy, which in most cases presents difficulties in diagnosis), special sensors are used: temporal, sphenoidal, nasopharyngeal. And, it should be noted, doctors have officially recognized that in many cases it is the nasopharyngeal lead that detects the focus of epileptic activity in the temporal region, while other leads do not react to it in any way and send normal impulses.

There are many mysteries in the human body, and not all are yet within the reach of doctors. The most complex and confusing of them is perhaps the brain. Various methods of brain research, such as electroencephalography, help doctors lift the veil of secrecy. What is it and what can a patient expect from the procedure?

Who should be examined using electroencephalography?

Electroencephalography (EEG) can help clarify many diagnoses related to infections, injuries, and brain disorders.

The doctor may refer you for examination if:

1. There is a possibility of epilepsy. Brain waves in this case show a special epileptiform activity, which is expressed in a modified form of graphs.
2. It is necessary to establish the exact location of the injured area of ​​the brain or tumor.
3. There are some genetic diseases.
4. There are serious disturbances in sleep and wakefulness.
5. The functioning of cerebral vessels is disrupted.
6. An assessment of the effectiveness of the treatment is needed.

The electroencephalography method is applicable to both adults and children; it is non-traumatic and painless. A clear picture of the work of brain neurons in different parts of the brain makes it possible to clarify the nature and causes of neurological disorders.

Brain research method electroencephalography - what is it?

This examination is based on recording bioelectric waves emitted by neurons in the cerebral cortex. Using electrodes, the activity of nerve cells is detected, amplified, and converted into a graphic form by the device.

The resulting curve characterizes the process of work of different parts of the brain, its functional state. In the normal state, it has a certain shape, and deviations are diagnosed taking into account changes in the appearance of the graph.

EEG can be performed in various ways. The room for it is isolated from extraneous sounds and light. The procedure usually takes 2-4 hours and is performed in a clinic or laboratory. In some cases, electroencephalography with sleep deprivation requires more time.

The method allows doctors to obtain objective data about the state of the brain, even when the patient is unconscious.

How is an EEG of the brain performed?

If a doctor prescribes electroencephalography, what does this mean for the patient? He will be asked to sit in a comfortable position or lie down, and a helmet made of elastic material that fixes the electrodes will be put on his head. If the recording is expected to be long-term, then a special conductive paste or collodion is applied to the places where the electrodes come into contact with the skin. The electrodes do not cause any unpleasant sensations.

The EEG does not suggest any violations of the integrity of the skin or the administration of drugs (premedication).

Routine recording of brain activity occurs for the patient in a state of passive wakefulness, when he lies quietly or sits with his eyes closed. This is quite difficult, time passes slowly and you need to fight sleep. The laboratory assistant periodically checks the patient’s condition, asks him to open his eyes and perform certain tasks.

During the examination, the patient should minimize any physical activity that would cause interference. It’s good if the laboratory manages to record neurological manifestations of interest to doctors (convulsions, tics, epileptic seizures). Sometimes an attack in epileptics is deliberately provoked in order to understand its type and origin.

Preparing for an EEG

The day before the test, you should wash your hair. It is better not to braid your hair or use any styling products. Leave the barrettes and clips at home, and tie long hair into a ponytail if necessary.

You should also leave metal jewelry at home: earrings, chains, lip and eyebrow piercings. Before entering the office, turn off your mobile phone (not just the sound, but completely) so as not to interfere with sensitive sensors.

Before the examination, you need to eat so as not to feel hungry. It is advisable to avoid any excitement and strong feelings, but you should not take any sedatives.

You may need a napkin or towel to wipe off any remaining fixative gel.

Tests during EEG

In order to track the reaction of brain neurons in various situations, and expand the indicative capabilities of the method, an electroencephalography examination includes several tests:

1. Eye opening-closing test. The laboratory assistant makes sure that the patient is conscious, hears him, and follows the instructions. The absence of patterns on the graph at the moment of opening the eyes indicates pathology.

2. Test with photostimulation, when flashes of bright light are directed into the patient’s eyes during recording. In this way, epileptimorphic activity is detected.

3. Test with hyperventilation, when the subject voluntarily breathes deeply for several minutes. The frequency of respiratory movements at this time decreases slightly, but the oxygen content in the blood increases and, accordingly, the supply of oxygenated blood to the brain increases.

4. Sleep deprivation, when the patient is put into a short sleep with the help of sedatives or remains in the hospital for daily observation. This allows you to obtain important data about the activity of neurons at the time of awakening and falling asleep.

5. Stimulation of mental activity consists of solving simple problems.

6. Stimulation of manual activity, when the patient is asked to perform a task with an object in his hands.

All this gives a more complete picture of the functional state of the brain and notices disorders that have minor external manifestations.

Duration of electroencephalogram

The procedure time may vary depending on the goals set by the doctor and the conditions of the specific laboratory:

• 30 minutes or more, if you can quickly register the activity you are looking for;
• 2-4 hours in the standard version, when the patient is examined reclining in a chair;
• 6 or more hours with EEG with daytime sleep deprivation;
• 12-24 hours, when all phases of night sleep are examined.

The planned time of the procedure can be changed at the discretion of the doctor and laboratory assistant in any direction, because if there are no characteristic patterns corresponding to the diagnosis, the EEG will have to be repeated, wasting extra time and money. And if all the necessary records have been received, there is no point in tormenting the patient with forced inaction.

Why is video monitoring needed during an EEG?

Sometimes electroencephalography of the brain is duplicated by a video recording, which records everything that happens during the study with the patient.

Video monitoring is prescribed to patients with epilepsy to correlate how behavior during a seizure relates to brain activity. Comparison of characteristic waves with a picture using a timer can clarify gaps in the diagnosis and help the doctor understand the condition of the subject for more accurate treatment.

Electroencephalography result

When the patient has undergone electroencephalography, the conclusion is given along with printouts of all graphs of wave activity in various parts of the brain. In addition, if video monitoring was also carried out, the recording is saved on a disk or flash drive.

During a consultation with a neurologist, it is better to show all the results so that the doctor can assess the characteristics of the patient’s condition. Electroencephalography of the brain is not the basis for diagnosis, but it significantly clarifies the picture of the disease.

To ensure that all the smallest teeth are clearly visible on the graphs, it is recommended to store the printouts flat in a hard folder.

Encryption from the brain: types of rhythms

When an electroencephalography has been completed, it is extremely difficult to understand what each graph shows on your own. The doctor will make a diagnosis based on studying changes in the activity of areas of the brain during the test. But if an EEG was prescribed, then the reasons were compelling, and it wouldn’t hurt to take a conscious approach to your results.

So, we have in our hands a printout of this examination, like electroencephalography. What are these - rhythms and frequencies - and how to determine the boundaries of the norm? The main indicators that appear in the conclusion:

1. Alpha rhythm. The normal frequency ranges from 8-14 Hz. Between the cerebral hemispheres there can be a difference of up to 100 µV. Pathology of the alpha rhythm is characterized by an asymmetry between the hemispheres exceeding 30%, an amplitude index above 90 μV and below 20.

2. Beta rhythm. Mainly fixed on the anterior leads (in the frontal lobes). For most people, a typical frequency is 18-25 Hz with an amplitude no higher than 10 μV. Pathology is indicated by an increase in amplitude above 25 μV and a persistent spread of beta activity to the posterior leads.

3. Delta rhythm and Theta rhythm. Fixed only during sleep. The appearance of these activities during wakefulness signals a disruption in the nutrition of brain tissue.

5. Bioelectric activity (BEA). A normal indicator demonstrates synchrony, rhythm, and the absence of paroxysms. Deviations appear in early childhood epilepsy, predisposition to seizures and depression.

In order for the results of the study to be indicative and informative, it is important to strictly follow the prescribed treatment regimen without stopping the medications before the study. Alcohol or energy drinks taken the day before can distort the picture.

Why is electroencephalography needed?

For the patient, the benefits of the study are obvious. The doctor can check the correctness of the prescribed therapy and change it if necessary.

In patients with epilepsy, when a period of remission has been established by observation, the EEG may show attacks that are not externally observable, which still require drug intervention. Or avoid unreasonable social restrictions by clarifying the specifics of the disease.

The study can also contribute to the early diagnosis of neoplasms, vascular pathologies, inflammation and brain degeneration.

The brain, regardless of whether a person is sleeping or engaged in mental work, exhibits bioelectrical activity. The method that records this activity is called electroencephalography, and the image obtained during the study is called an electroencephalogram (EEG).

Electroencephalography is widely used in both pediatric and adult neurology. Using an EEG, an experienced doctor can assess the state of the brain, detect areas of ischemic, traumatic or any other lesion in it, and also identify foci of epileptic activity in the brain tissue. You can undergo this examination in specialized psychoneurological treatment institutions and multidisciplinary diagnostic centers. Referrals for EEG are given by adult and pediatric neurologists, neurosurgeons and psychiatrists.

What does an electroencephalogram show?

Electroencephalography is one of the main instrumental methods for examining patients with neurological, mental and speech disorders. Indications for EEG are the following pathological conditions:

How to properly prepare for research

EEG does not require any special preparation. Before the procedure, it is advisable not to drink alcohol or strong coffee, not to smoke, not to engage in heavy physical labor and not to be very nervous, as this may distort the results of the study.

There is no need to starve or diet; on the contrary, you cannot go to research without eating. Hunger and a drop in blood sugar concentration (hypoglycemia) provoke changes in brain activity, which can be regarded by a doctor as a sign of pathology, although in fact there is none.

For people taking psychotropic medications, preparation for an EEG may involve temporarily stopping one or another medication. However, you should not make any adjustments to the course of treatment yourself. All appointments must be made by a doctor who gives a referral for an EEG.

In patients with suspected epilepsy, electroencephalography is often performed not according to the standard method, but during sleep or vice versa after prolonged abstinence from sleep.

With the help of such techniques, doctors are able to record abnormal brain activity that is not always noticeable during a normal examination. If you plan to conduct an EEG using one of these methods, special preparation may be required: abstaining from sleep for 24-36 hours or taking sleeping pills.

How is electroencephalography performed? Electroencephalography is a non-invasive study that does not involve exposure of the human body to any radiation.

To conduct an electroencephalographic study, the patient is placed on a special chair or couch (usually in a reclining position), a special gel is applied to the head and a cap with electrodes is attached, each of which must be located clearly above its own area of ​​the brain. When the device is turned on, the subject should be as calm and motionless as possible. If there is a need to change position, registration of the electroencephalogram is suspended.

During the study, the doctor usually asks the patient to do some manipulations: open and close his eyes, breathe deeply and often, watch the flashing light, etc. This stress tests which allow the doctor to evaluate the brain's response to stimuli. With their help, they can reveal what remains hidden when a person remains absolutely calm.

Decoding the electroencephalogram

The bioelectrical activity of the brain, recorded by an electroencephalograph, is displayed on paper in the form of curved lines - waves (rhythms). There are as many of them as there are electrodes located on the subject’s head. Each such wave has its own amplitude and oscillation frequency. Depending on the magnitude of these indicators, the following EEG rhythms are distinguished:

• Alpha rhythm(8-13 vibrations per second). It is typical for an adult and completely healthy person who is in a state of calm wakefulness. This rhythm is best expressed in the leads of the occipital and parietal regions of the brain.
• Beta rhythm, its frequency is higher than that of the alpha rhythm. The predominance of this rhythm is observed during active wakefulness, mental stress, emotional arousal, and the stage of REM sleep. The beta rhythm is generated by the frontal lobes of the cerebral hemispheres.
• Gamma rhythm. It has a frequency even higher than that of the beta rhythm. This brain activity occurs in a state of maximum concentration.
• Theta rhythm– lower in frequency than the alpha rhythm. It is most pronounced in children 2-8 years old; in adults it can occur during sleep.
• Delta rhythm– the rhythm of the lowest frequency. Typical for healthy babies in the first year of life, it can also be considered a variant of the norm for children under 6 years of age (it all depends on clinical data). In adults, the delta rhythm appears during very deep natural sleep, general anesthesia, and coma. In a state of wakefulness, this rhythm occurs when EEG is recorded from areas of the brain bordering pathological lesions and tumors.
• Straight line - there is no rhythm. This EEG pattern indicates the absence of electrical activity in the brain, that is, its possible death.

Since each of the described rhythms corresponds to a specific state of the brain, the replacement of one rhythm with another may indicate the presence of pathology. In addition, the appearance of waves that are uncharacteristic for some derivation or a significant increase or decrease in the amplitude of their oscillations is also regarded as a deviation from the norm.

In order to decipher the electroencephalogram as correctly as possible, the doctor must take into account the patient’s age (for children, adults and the elderly, their own norms of bioelectrical activity of brain tissue) and separately evaluate the data obtained at rest and with stimulation.

Thus, by examining the EEG, a specialist (a doctor engaged in functional diagnostics) can determine whether there is a deviation from the norm, which particular part of the brain generates “wrong” waves, distinguish diffuse damage to brain tissue from local damage, a superficial pathological focus from a deep one, identify epileptic activity, recognize coma and determine the degree of its severity.

This data is indispensable for neuropathologists and neurosurgeons; thanks to it, doctors are able to “look” into the patient’s brain, understand what is happening there, and, based on the information received, choose the most correct treatment tactics.

Zubkova Olga Sergeevna, medical observer, epidemiologist

Navigation

Encephalography of the brain is a method of diagnostic examination of an organ, which allows one to evaluate its electrical activity. A simple and painless procedure is needed to identify increased convulsive readiness of the cortex of an important part of the central nervous system. An encephalogram of the head, as the EEG of the brain is also called, can: confirm or refute epilepsy, structural and metabolic lesions of the organ, identify the cause of sleep disturbances, and assess the condition of tissues after a stroke. What is EEG in practice - a schematic recording of the work of neurons in various parts of the brain using electrodes that are placed on a person’s head.

Indications and contraindications

Even if the same disease is suspected in different patients, the decision on the appropriateness of the approach is made by a specialist. For example, an EEG for migraine in some cases helps to distinguish the disease from epilepsy, but in others it will only provoke a new attack.

Indications for EEG

The need to undergo an examination may be necessary if the development of a pathological process is suspected, to evaluate the treatment provided, and to establish the optimal method of therapy. Representatives of a number of professions are required to attend sessions to check brain function indicators and their compliance with standards.

Indications for EEG in adults:

• confirmation of epilepsy, degenerative, vascular or inflammatory organ lesions;
• identifying the location of tumors, cysts, traumatic tissue damage;
• the need to distinguish visual or hearing impairments from their simulation;
• assessing the brain function of a person who is in a coma;
• identifying the causes of sleepwalking, sleep disturbances, confusion, dizziness, surges in blood pressure;
• establishing the quality of blood vessels and tissue functionality.

In childhood, examinations are carried out for the same reasons. One more thing is added to them - assessment of the functional state of the central nervous system by studying the degree of its maturation at a specific stage. In some cases, the technique allows us to identify the causes of stuttering and speech disorders in a child.

Contraindications

People with acute respiratory infections, acute respiratory infections, nasal congestion or cough will have to wait with an EEG. The session is not performed for various mental disorders. If the test causes a person too much discomfort and leads to hysteria due to inexplicable fears, it is better to try other diagnostic methods. Physiologically there are no contraindications to the approach. It does not cause discomfort and does not have any effect on the human condition.

What does an encephalogram of the brain show?

Having taken an electrocardiogram of the head - another option for the name of the session - the doctor receives a list of data. Each of the indicators has its own normal limits and nuances of interpretation. They indicate not only the activity of the brain, but can also indicate areas affected by the disease. Despite the fact that the main work of assessing the functioning of one of the parts of the central nervous system lies on the computer, the machine is not able to independently identify the problem and make a diagnosis.

Only an experienced specialist can understand what the EEG of the brain shows. Attempts to independently decipher the examination results can lead to neurosis or psychosis due to suspicions about the diagnosis. In some cases, patients are additionally prescribed rheoencephalography (REG) of the organ, which makes it possible to study in detail the features of the functioning of its vessels.

Bioelectric activity of the brain BEA

The indicator records waves formed as a result of the transmission of impulses between cells. According to the standard, they must be synchronous, consistent, without failures or amplifications. Situations with non-rhythmic, unusually accelerated oscillation frequency or amplitude data above accepted norms are characteristic of a number of physiological conditions and diseases.

Typically, pathological changes are observed when:

• injuries and concussions;
• inflammatory tissue lesions - encephalitis, meningitis and others;
• age-related changes in the brain - Parkinson's disease, Alzheimer's disease;
• narrowing of the lumen of blood vessels;
• irradiation and poisoning;
• the presence of epilepsy or migraine;
• structural changes in the hypothalamus and pituitary gland.

Changes in the bioelectrical activity of the brain are not always the result of a disease. Slowed functioning of neuron cells with a decrease in BEA is characteristic of depression. For this reason, electroencephalography should be performed when indicated. When making a diagnosis, the results of additional studies and clinical picture data must be taken into account.

Electroencephalogram rhythms

When deciphering the electroencephalogram of the brain, the specialist pays special attention to biorhythms. This takes into account the situation and time period in which the data was taken. The rhythms are affected by the functionality of the central nervous system, a person’s mood, medication intake, and the degree of activity of the body (during sleep or wakefulness).

Alpha and beta rhythms, theta and delta indicators are of main importance. Additional data is usually taken into account in more complex tests that are carried out against the background of mental or intellectual stress.

Alpha rhythm

In an adult, its indicators should be in the range of 8-13 Hz with an amplitude of up to 100 μV. Rhythmic disturbances, frequency instability, detection of paroxysms or arches, asymmetry between the hemispheres indicate pathology. The cause of the phenomenon is often a tumor, cyst, stroke, scar formation on tissue, brain injury, acquired dementia. Data failures in children can be recorded in cases of delayed psychomotor development, neuroses, or the presence of psychopathology.

Beta rhythm

It is more pronounced in the frontal lobes than in other areas. It is characterized by a symmetrical amplitude in the hemispheres within 3-5 μV. Problems are indicated by the presence of paroxysms, excess amplitude, asymmetry, and changes in the rhythm graph. Deviation from the norm may indicate brain diseases such as encephalitis, neurosis, concussion and developmental delay in the child.

Theta rhythm and delta rhythm

Slow theta and delta waves in people over 21 years of age are not recorded during wakefulness. The first ones are recorded against the background of falling asleep, superficial sleep and during dreams. The latter are characteristic of a deep blackout of consciousness. Up to this age, “failures” in this area may be a variant of the norm, but for this to happen, certain factors must converge. Disturbed theta rhythm and delta rhythm are signs of the presence of a tumor, neurosis, psychopathy, acquired dementia, asthenic syndrome, and twilight state.

How to prepare for an encephalogram of the brain

Even in adults, the procedure causes fears, but they are in vain. The process of influencing the contents of the skull through electrodes is absolutely safe and is not accompanied by any sensations. Sessions can be held at least every day an unlimited number of times. Electrical tomography does not require complex and lengthy preparations. In some cases, you can do without them altogether.

Preparation for an EEG for an adult looks like this:

• 2 days before the session, you must stop drinking alcohol and stimulating drinks (coffee, cocoa, energy drinks), and eating chocolate;
• You should take care to keep your hair clean; using any styling products is prohibited;
• 2 hours before the procedure you should not eat heavily or smoke;
• Before the event, you must remove metal objects from your head (jewelry, piercings, hairpins).

Ideally, the doctor who prescribed the procedure should tell you how to prepare for the EEG. He must inform you which medications should be stopped and for what period before the study. If this is not possible, a corresponding note is made at the appointment for the specialist who will interpret the results.

How is an EEG performed?

In practice, the examination method is very simple. The patient sits in a comfortable chair, 21 electrodes are attached to his head, and sometimes a cap is put on top of them for additional fixation. To increase the conductivity of devices, their surface or skin is lubricated with gel. The specialist turns on the device and data recording begins.

In some cases, during encephalography, the patient is exposed to provocative tests. They are resorted to when routine checks are insufficiently informative in case of suspected epilepsy. How long the procedure lasts depends on its type, goals and the person’s condition. It can take from 15-30 minutes to 8 hours.

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EEG results

After completing the procedure, the employee who took the indicators receives the data on electronic or paper media. He compares all the results of the electroencephalogram to decipher the EEG. Then he draws up a conclusion and pastes it into the patient’s medical record. Today, many clinics provide clients with the opportunity to receive an EEG recording in electronic form to show it to a doctor or specialist in this field.

The final EEG conclusion consists of three parts:

• characteristics of wave activity and their typical affiliation;
• conclusion on the description made and its decoding;
• identifying the correspondence of study results to symptoms and the expected diagnosis.

When deciphering EEG parameters of the brain, the age and characteristics of the patient’s condition, the clinical picture, and the list of therapeutic manipulations performed are taken into account. The results of the study are extremely specific and almost not informative for an outsider.

Features of EEG in children

Taking encephalogram data from a child’s brain can cause a lot of trouble for parents and specialists. The first thing you need to remember is that the session is absolutely safe. The current strength during the procedure is so insignificant that the small patient will not feel anything. Parents' nervousness can negatively affect the kids' mood and distort the results, so you need to control yourself.

Preparing the child for the procedure

An EEG of the brain in children under one year of age is always performed during sleep. At this moment, the baby is in the arms of his father or mother. It is enough to wait for the right moment and carefully carry out the stages of the session. Usually the manipulation takes no more than 15-20 minutes. Children under 3 years of age also usually undergo the procedure while on vacation. The exception is for calm and sociable children, but this is done only if it is impossible to wait for them to fall asleep.

Features of preparing children for EEG of the brain depend on the age and condition of the patient:

• up to one year - you need to take care of the cleanliness of the child’s head and feed him immediately before visiting a specialist so that he falls asleep before the session begins;
• up to three years - you should also wash the baby’s hair and bring him to the diagnostic facility at the time when he is scheduled to sleep;
• after three years - in addition to washing your hair, you need to think about a distraction for the baby. Taking correct indicators of brain function in a child is possible only if he is calm. The desired effect can be achieved by preparing the patient by creating an appropriate mood or a favorite toy.

The procedure itself differs from the adult version only in the number of electrodes - no more than 12 of them are used. During the session, you need to make sure that the baby’s head is in one position and does not lean forward. In the case of older children, additional tests may be necessary. The child will be asked to close and open his eyes, clench his fingers into a fist, listen to special sounds, inflate a balloon, and look at a flashing light bulb.

Where to do an encephalogram of the brain

Contrary to popular belief, you do not have to go to paid medical clinics to undergo an EEG. Private commercial neurological institutions provide such services to adults and children, but the cost of their services is often several times higher than the regional average prices.

Where an EEG can be done depends on the patient’s age:

• adults can go to a neurological clinic, a city or regional hospital according to their profile, or a psychiatric clinic;
• Children and adolescents under 14 years of age should be examined in specialized children's hospitals under the supervision of pediatricians.

There is only one drawback to applying to budget organizations - usually there is a waiting list for such procedures. Sometimes you have to wait several days or even weeks to see a specialist. Sometimes, diagnostic rooms are limited to conducting analysis, and are sent to other specialists for decoding and conclusions, which additionally takes up time.

Cost of the procedure

The price for an electroencephalogram of the brain depends on the type of medical institution, city, option and duration of the procedure. In the regions, the cost of the service during the waking period starts from 800-1000 rubles. In Moscow, prices for sessions start from 1,500 rubles. Monitoring during sleep will cost 8,000-12,000 rubles in Moscow and 10-20% less in regional centers. These amounts include the costs of medical personnel and equipment operation. Discounts on such services are questionable; you should not trust such offers.

Even with the advent of such methods for diagnosing brain diseases as CT and MRI, the value of EEG has not decreased. A simple and safe examination sometimes helps to identify pathologies where modern methods are powerless. If your doctor recommends a procedure, you should not refuse. Already during the session, an experienced specialist can detect degenerative changes in the tissues of the organ. This will allow you to select the appropriate treatment and begin implementing the plan in a timely manner.

Electroencephalography is an effective method for studying the state of the nervous system. The EEG of the brain is of great importance: decoding the indicators of this examination allows you to analyze the performance of the brain as a whole, identify changes in its functioning, and identify pathologies and disorders. To carry it out, a cap with electrodes is placed on a person’s head, which record the activity of all parts of the brain. The resulting curve, on which biocurrents are recorded, is called an electroencephalogram. This study serves as the basis for making a diagnosis and prescribing therapy, helps to monitor the dynamics and progress of treatment.

Electroencephalography is effective in cases of suspected brain tumors, epilepsy, and vascular diseases. It also reflects disturbances in brain activity due to traumatic brain injury and inflammatory processes. EEG is also valuable in the case of some mental and neurotic abnormalities and disorders. In addition, electroencephalography reflects age-related changes in the functioning of the nervous system.

Based on the results of the EEG, a neurologist's report is issued - most often a day or two after the examination. When making a diagnosis and prescribing treatment, not only electroencephalography data are taken into account, but also reactions during examination by a doctor, clinical manifestations, and indicators of other studies.

EEG decoding includes an assessment of the constancy of brain rhythms, the same activity of neurons in both hemispheres and the reaction to routine tests (open-close eyes, photostimulation, hyperventilation).

EEG in children is more difficult to decipher - this is due to the active growth and maturation of the entire nervous system, which can affect the EEG results. Therefore, in children, any disorders and changes should be analyzed over time with a certain periodicity.

Decoding the EEG of the brain must take into account a number of factors, the influence of which may reduce the accuracy of the study. These include:

• age;
• health status and concomitant diseases;
• active movement during the procedure;
• tremor;
• visual impairment;
• taking certain medications that affect the nervous system;
• consumption of products that stimulate the nervous system (containing caffeine);
• conducting an EEG on an empty stomach;
• dirty hair, use of hair styling and treatment products;
• other factors that influence the activity of the brain and neurons.

Decoding the EEG taking into account these conditions will allow you to avoid errors in the conclusion.

Brain rhythms are one of the key parameters when assessing EEG results. These are waves that differ from each other in shape, constancy, periods of oscillation and amplitude. Their regularity reflects the normal coordinated activity of various structures of the central nervous system.

There are several types of rhythms, each of which has its own set of characteristics and records specific brain activity:

1. The alpha rhythm is detected at rest. Normally, when a person does not sleep with drooping eyelids, the frequency of the alpha rhythm is 8-14 Hz, and the amplitude is up to 100 μV. It is most intensely manifested in the area of ​​the back of the head and crown. Alpha waves become almost undetectable during mental activity, flashes of light or eye opening, nervous excitement, or sleep. The frequency of the alpha rhythm may increase in women during menstruation.
2. Beta rhythm is an indicator of active brain function. It may also reflect increased anxiety, nervousness, depression, or taking too much of certain medications. The normal frequency of the beta rhythm in both hemispheres is 14-30 Hz, amplitude is 3-5 μV. The highest intensity of beta waves is recorded in the frontal lobes of the brain.
3. The delta rhythm has a normal frequency of 1-4 Hz with an amplitude of up to 40 μV and is reflected in the EEG when a person is sleeping. At other times, its waves can account for no more than 15% of all rhythms. In addition, the delta rhythm can reflect being in a coma, the effect of drugs, and indicate the appearance of a tumor or brain damage.
4. The theta rhythm also characterizes the sleep of a healthy adult. In children under 4-6 years of age, it is the main one on the EEG - it can be detected in the central parts of the brain as early as 3 weeks of age. The frequency of the theta rhythm is 4-8 Hz with an amplitude of about 30 μV.

Based on the results of the EEG, another parameter is derived, which is a comprehensive assessment of brain rhythms - bioelectrical activity of the brain (BEA). The doctor examines the rhythms for synchronicity, rhythmicity and the presence of sudden bursts. Based on the analysis, the neurologist writes a conclusion, which must contain the characteristics of the waves, a description of the disorders and their correspondence to clinical manifestations.

Normally, the manifestations of brain rhythms in a healthy person correspond to the above values ​​and functional states. In addition, the following signs indicate normal functioning of the nervous system:

• the predominance of alpha and beta rhythms in the active state;
• synchronization of rhythms in both hemispheres;
• absence of sharp peaks of electrical activity;
• stable brain activity even in the presence of short-term reactions to light exposure and other stimulation options.

In children, slow oscillations are recorded at an early age, and the alpha rhythm is formed by the age of 7 years. The EEG of adolescents 15-17 years old already corresponds to the study of an adult. After 50-60 years, the frequency decreases and the regularity of the delta rhythm is disrupted, and the number of theta waves increases.

There are many deviations from the norm in the EEG of the brain. Determining the possible causes of brain rhythm disturbances is the task of an experienced specialist. Below are some abnormal EEG findings that may be signs of neurological, mental or speech disorders.

1. Lack of synchrony and symmetry in the work of neurons in the right and left hemispheres.
2. Sudden changes in rhythm frequency: acute bursts of activity and sharp declines. This happens with infections, tumors, injuries, strokes.
3. Alternating peaks and valleys, high amplitude fluctuations with different frequencies, single or serial bursts of activity can be a sign of epilepsy. However, it should be taken into account that between attacks the EEG of patients with epilepsy may show normal results.
4. The presence of delta and theta rhythms in a awake person indicates possible diseases or injuries of the brain.
5. A number of infections, poisonings and metabolic disorders can be characterized by changes in brain activity in several areas at once.
6. In a coma and when the nervous system is suppressed by potent drugs, zero electrical activity in the brain can be observed. This happens when the flow of blood to the brain is disrupted and it stops functioning.

Possible causes of violations

1. Alpha rhythm disorders. Asymmetry of the alpha rhythms of the two hemispheres of the brain (a difference of more than 30%) may be a sign of neoplasms, stroke or heart attack. An unstable or high-frequency alpha rhythm occurs with brain damage, in particular as a result of a head injury or concussion. In case of serious mental disorders, the amplitude may decrease to less than 20 μV, the rhythm index drops below 50%, and the zone of alpha rhythm manifestation shifts from the occipital and crown areas. With dementia, there may be an absence of alpha waves or their arrhythmia. In a child, deviations from the norm of the alpha rhythm may be evidence of delayed psychomotor development.
2. Beta rhythm disorders. Concussion is usually characterized by the presence of high-amplitude (50-60 μV) diffuse beta waves. With encephalitis, short spindles are recorded. An increase in the duration and frequency of occurrence of these spindles may indicate a developing inflammatory process. In children, beta waves with a frequency of 16-18 Hz and high amplitude (30-40 μV) in the anterior and central parts of the brain are abnormal - this is a sign of a child’s developmental delay.
3. Disturbances of theta and delta rhythm. A constant increase in the amplitude of the delta rhythm - more than 40 μV - is an indicator of impaired brain functions. If the delta rhythm is recorded in all parts of the brain, then we can talk about serious diseases of the central nervous system. Large fluctuations in delta waves occur in the presence of tumors. Developmental delay in children is characterized by maximum manifestations of theta and delta waves in the back of the head. An increased frequency of these rhythms sometimes reflects impaired cerebral circulation and other neurological problems.

Timely EEG of the brain and proper interpretation of the results will help establish a diagnosis in case of disorders and prescribe adequate therapy for brain diseases.