How to make an encephalogram of the brain. What to bring with you. Rhythms of brain activity

It is known that the human brain is, today the development of science, the most subtle and mysterious matter available for our study. What is even more surprising is the fact that we study the human brain also with the help of the brain, only this time the researcher. This means that the human brain is a matter prone to self-knowledge.

So far, science cannot find another analogue for the brain.

But how can you fix the traces of thoughts, and in general, any activity of the brain? For this, such a study as an EEG is carried out, or brain encephalogram.

In fact, this "folk term" is quite illiterate. After all, the very word "encephalogram" means "encephalon" plus "graphos", that is, a record of the activity of the brain. Therefore, it is enough to simply say “encephalogram”. There are simply no other encephalograms, except for the brain. But we will use the usual term so that there is no confusion in the minds of readers.

How is this study different from others?

CT, Ultrasound, MRI, EchoEG and EEG, or big confusion

People without medical education get confused trying to unravel the numerous abbreviations. In fact, everything is very simple: CT and MRI show internal structure organs and brain, exactly as it would be seen at autopsy.

Ultrasound shows, in addition, the processes visible to the eye: contraction of the heart, the movement of blood through the vessels. EchoEG indicates the symmetry of the reflection of the signal inside the brain, from which a conclusion is made about structural anomalies.

But only EEG captures the invisible, that is, it registers the biological currents of the brain, which are the "echoes" of its secret and explicit work. In the event that you make an encephalogram of the brain, you can see chaotic lines. Therefore, in addition to recording, a qualified interpretation of the encephalogram of the brain is required. It is performed by a neurophysiologist, and then transfers the results and their interpretation to the doctor. Usually this study is ordered by neurologists. How is the study going, and what do its results say?

No need to be afraid

If you have to make an encephalogram of the child's brain , then you need to warn that you do not need to be afraid. It won't hurt, but it will be very interesting. They will put a beautiful wig on their heads, they will put them on a comfortable chair, like an astronaut, and they will ask them to breathe, and then a light bulb will blink. And in general, it's all very similar to flying into space.

How is this research actually done?

• First, a rubber "harness" is put on the patient's head to attach the electrodes;

• then the scalp is lubricated with a conductive gel, and, according to a special scheme, the electrodes are fixed on the rubber rims so that they fit snugly against the scalp, and the wires are attached.

This completes the preparation, the patient is seated in a chair, the lights are turned off, and they are asked to relax. The laboratory assistant - neurophysiologist leaves for another room. Sometimes she will ask for deep and strong breaths, and then suddenly a bright lamp will flash in her eyes.

What are they studying?

The biocurrents of neurons in the cerebral cortex are very weak. If a person rotates his eyes closed, wrinkles his forehead, then these signals will drown out the activity of the cortex, and the doctor will not understand anything, so you need to sit relaxed.

An encephalogram can show such disorders that other research methods cannot see: this is a predisposition to convulsive manifestations, and epileptic seizures. Therefore, the exclusion of epilepsy, or any epileptiform activity, is the main indication for an encephalogram, or EEG for short.

Therefore, it is usually prescribed:

• specialists - epileptologists in the treatment and management of patients;

• during professional examinations of pilots, railway workers, drivers;

• when calling for active military service and examining the health of the conscript;

• in forensic medical and forensic psychiatric examination;

• just to check the work of the cerebral cortex, when patients complain of fainting, loss of consciousness, and other symptoms that can hide epilepsy under the mask.

An encephalogram of the child's brain can be prescribed for autism, or vice versa, motor hyperreactivity, psychomotor agitation, night terrors and other complaints.

What epilepsy looks like on EEG results

It’s not worth it to be afraid, and even more so to panic, if the doctor has prescribed an EEG for a child: no one writes your child into “seizures” and epileptics. To detect epileptiform activity, must be strong indications: the appearance of a pathological delta - rhythm, and the appearance of complexes of the "peak - wave" type.

In order to provoke the body to this activity, tests are carried out that lower the excitability threshold of neurons: with deep and frequent breathing, there is an excess of oxygen in the blood, which contributes to the appearance of seizures.

One of the best ways to identify hidden pathology is sleep deprivation. This means that if the patient does not sleep at all the night before the study, and does not even lie down, then there is a much higher probability of detecting a tendency to epileptiform activity.

Where to make an encephalogram the brain of an adult and a child? Usually this study is carried out in large clinics, or in specialized diagnostic centers located in large cities. Usually this study is free, but you can wait two to three months for your turn.

In conclusion, it must be said that the main thing that you can do to get correct result- this is to relax all the muscles, not to move your arms, legs, facial muscles and especially your eyes. At the same time, you must carefully follow all the commands of the laboratory assistant and the doctor. This is the only way to get valuable results with which you can work further.

Brain activity, the state of its anatomical structures, the presence of pathologies is studied and recorded using various methods - electroencephalography, rheoencephalography, computed tomography, etc. A huge role in identifying various abnormalities in the functioning of brain structures belongs to the methods of studying its electrical activity, in particular electroencephalography.

Electroencephalogram of the brain - definition and essence of the method

Electroencephalogram (EEG) is a record of the electrical activity of neurons in various brain structures, which is done on special paper using electrodes. Electrodes are applied to various parts of the head and record the activity of one or another part of the brain. We can say that an electroencephalogram is a record of the functional activity of the brain of a person of any age.

The functional activity of the human brain depends on the activity of the median structures - reticular formation and forebrain , which predetermine the rhythm, general structure and dynamics of the electroencephalogram. A large number of connections of the reticular formation and the forebrain with other structures and the cortex determine the symmetry of the EEG, and its relative "similarity" for the entire brain.

The EEG is taken in order to determine the activity of the brain in various lesions of the central nervous system, for example, with neuroinfections (poliomyelitis, etc.), meningitis, encephalitis, etc. Based on the results of the EEG, it is possible to assess the degree of brain damage due to various causes, and to clarify specific location that has been damaged.

The EEG is taken according to the standard protocol, which takes into account the recording in the state of wakefulness or sleep (infants), with special tests. Routine EEG tests are:
1. Photostimulation (exposure to flashes of bright light on closed eyes).
2. Opening and closing eyes.
3. Hyperventilation (rare and deep breathing for 3 to 5 minutes).

These tests are performed on all adults and children when taking an EEG, regardless of age and pathology. In addition, when taking an EEG, additional tests may be used, for example:

• clenching fingers into a fist;
• sleep deprivation test;
• stay in the dark for 40 minutes;
• monitoring of the entire period of night sleep;
• reception medicines;
• performing psychological tests.

Additional tests for EEG are determined by a neurologist who wishes to evaluate certain functions of the human brain.

What does an electroencephalogram show?

An electroencephalogram reflects the functional state of brain structures in various human states, for example, sleep, wakefulness, active mental or physical work, etc. An electroencephalogram is an absolutely safe method, simple, painless and does not require serious intervention.

To date, the electroencephalogram is widely used in the practice of neurologists, since this method allows diagnosing epilepsy, vascular, inflammatory and degenerative brain lesions. In addition, EEG helps to find out the specific position of tumors, cysts and traumatic injuries of brain structures.

An electroencephalogram with patient irritation by light or sound makes it possible to distinguish true visual and hearing impairments from hysterical ones, or their simulation. The EEG is used in intensive care units for dynamic monitoring of the condition of patients in a coma. The disappearance of signs of electrical activity of the brain on the EEG is a sign of death of a person.

Where and how to do it?

An electroencephalogram for an adult can be taken in neurological clinics, in departments of city and district hospitals, or at a psychiatric dispensary. As a rule, an electroencephalogram is not taken in polyclinics, but there are exceptions to the rule. It is better to contact a psychiatric hospital or a neurology department, where specialists with the necessary qualifications work.

An electroencephalogram for children under 14 years of age is taken only in specialized children's hospitals where pediatricians work. That is, you need to go to the children's hospital, find the neurology department and ask when the EEG is taken. Psychiatric dispensaries generally do not take EEGs for young children.

In addition, private medical centers specializing in diagnostics and treatment neurological pathology also provide an EEG service for both children and adults. You can contact the multidisciplinary private clinic, where there are neurologists who will take an EEG and decipher the recording.

An electroencephalogram should be taken only after a good night's rest, in the absence of stressful situations and psychomotor agitation. Two days before the EEG is taken, it is necessary to exclude alcoholic drinks, sleeping pills, sedatives and anticonvulsants, tranquilizers and caffeine.

Electroencephalogram for children: how the procedure is performed

Taking an electroencephalogram in children often raises questions from parents who want to know what awaits the baby and how the procedure goes. The child is left in a dark, sound and light insulated room, where he is laid on a couch. Children under 1 year of age are in the mother's arms during the EEG recording. The whole procedure takes about 20 minutes.

To record an EEG, a cap is put on the baby's head, under which the doctor places electrodes. The skin under the electrodes is urinated with water or gel. Two inactive electrodes are applied to the ears. Then, with crocodile clips, the electrodes are connected to the wires connected to the device - the encephalograph. Because the electric currents are very small, then an amplifier is always needed, otherwise the activity of the brain will simply be impossible to register. It is the small strength of the currents that is the key to the absolute safety and harmlessness of the EEG, even for infants.

To begin the study, you should lay the head of the child evenly. Anterior leaning should not be allowed as this may cause artifacts to appear that will be misinterpreted. An EEG is taken for babies during sleep, which occurs after feeding. Wash your child's head before taking an EEG. Do not feed the baby before leaving the house, this is done immediately before the study, so that the baby eats and falls asleep - after all, it is at this time that the EEG is taken. To do this, prepare formula or express breast milk into a bottle to use in the hospital. Up to 3 years, EEG is taken only in a state of sleep. Children over 3 years old can stay awake, and to keep the baby calm, take a toy, book, or anything else that will distract the child. The child should be calm during the EEG.

Usually, the EEG is recorded as a background curve, and tests are also performed with opening and closing the eyes, hyperventilation (rare and deep breathing), and photostimulation. These tests are part of the EEG protocol, and are carried out for absolutely everyone - both adults and children. Sometimes they are asked to clench their fingers into a fist, listen to various sounds, etc. Opening the eyes makes it possible to assess the activity of inhibition processes, and closing them allows us to assess the activity of excitation. Hyperventilation can be carried out in children after 3 years in the form of a game - for example, invite the child to inflate a balloon. Such rare and deep breaths and exhalations last 2-3 minutes. This test allows you to diagnose latent epilepsy, inflammation of the structures and membranes of the brain, tumors, dysfunction, overwork and stress. Photostimulation is carried out with the eyes closed, when the light is flashing. The test allows you to assess the degree of delay in the mental, physical, speech and mental development of the child, as well as the presence of foci of epileptic activity.

Electroencephalogram rhythms

The electroencephalogram should show a regular rhythm of a certain type. The regularity of rhythms is ensured by the work of the part of the brain - the thalamus, which generates them, and ensures the synchronism of the activity and functional activity of all structures of the central nervous system.

On the human EEG, there are alpha, beta, delta and theta rhythms, which have different characteristics and reflect certain types of brain activity.

alpha rhythm has a frequency of 8 - 14 Hz, reflects the state of rest and is recorded in a person who is awake, but with his eyes closed. This rhythm is normally regular, the maximum intensity is recorded in the region of the occiput and crown. The alpha rhythm ceases to be determined when any motor stimuli appear.

beta rhythm has a frequency of 13 - 30 Hz, but reflects the state of anxiety, anxiety, depression and the use of sedatives. The beta rhythm is recorded with maximum intensity over the frontal lobes of the brain.

Theta rhythm has a frequency of 4 - 7 Hz and an amplitude of 25 - 35 μV, reflects the state of natural sleep. This rhythm is normal EEG of an adult person. And in children, it is this type of rhythm that prevails on the EEG.

delta rhythm has a frequency of 0.5 - 3 Hz, it reflects the state of natural sleep. It can also be recorded in the state of wakefulness in a limited amount, a maximum of 15% of all EEG rhythms. The amplitude of the delta rhythm is normally low - up to 40 μV. If there is an excess of the amplitude above 40 μV, and this rhythm is recorded for more than 15% of the time, then it is referred to as pathological. Such a pathological delta rhythm indicates a violation of the functions of the brain, and it appears precisely above the area where pathological changes develop. The appearance of a delta rhythm in all parts of the brain indicates the development of damage to the structures of the central nervous system, which is caused by liver dysfunction, and is proportional to the severity of impaired consciousness.

Electroencephalogram results

The result of an electroencephalogram is a record on paper or in computer memory. Curves are recorded on paper, which are analyzed by the doctor. The rhythmicity of waves on the EEG, frequency and amplitude are assessed, characteristic elements are identified with fixation of their distribution in space and time. Then all the data are summarized and reflected in the conclusion and description of the EEG, which is pasted into the medical record. The conclusion of the EEG is based on the shape of the curves, taking into account the clinical symptoms that the person has.

Such a conclusion should reflect the main characteristics of the EEG, and includes three mandatory parts:
1. Description of the activity and typical affiliation of EEG waves (for example: "An alpha rhythm is recorded over both hemispheres. The average amplitude is 57 μV on the left and 59 μV on the right. The dominant frequency is 8.7 Hz. The alpha rhythm dominates in the occipital leads").
2. Conclusion according to the description of the EEG and its interpretation (for example: "Signs of irritation of the cortex and median structures of the brain. Asymmetry between the cerebral hemispheres and paroxysmal activity was not detected").
3. Determination of the correspondence of clinical symptoms with the results of the EEG (for example: "Objective changes in the functional activity of the brain were recorded, corresponding to the manifestations of epilepsy").

Deciphering the electroencephalogram

Deciphering an electroencephalogram is the process of interpreting it, taking into account the clinical symptoms that the patient has. In the process of decoding, the basal rhythm, the level of symmetry in the electrical activity of brain neurons in the left and right hemispheres, spike activity, EEG changes against the background of functional tests (opening - closing the eyes, hyperventilation, photostimulation) must be taken into account. The final diagnosis is made only taking into account the presence of certain clinical signs that disturb the patient.

Deciphering the electroencephalogram involves interpreting the conclusion. Consider the basic concepts that the doctor reflects in the conclusion, and their clinical significance(that is, what these or other parameters can talk about).

Alpha - rhythm

Normally, its frequency is 8 - 13 Hz, the amplitude varies up to 100 μV. It is this rhythm that should prevail over both hemispheres in healthy adults. Pathologies of the alpha rhythm are the following signs:

• constant registration of the alpha rhythm in the frontal parts of the brain;
• interhemispheric asymmetry above 30%;
• violation of sinusoidal waves;
• paroxysmal or arcuate rhythm;
• unstable frequency;
• amplitude less than 20 μV or more than 90 μV;
• rhythm index less than 50%.

What do common alpha rhythm disturbances indicate?
Pronounced interhemispheric asymmetry may indicate the presence of a brain tumor, cyst, stroke, heart attack, or a scar at the site of an old hemorrhage.

The high frequency and instability of the alpha rhythm indicate traumatic brain damage, for example, after a concussion or a traumatic brain injury.

Disorganization of the alpha rhythm or its complete absence indicates acquired dementia.

About the delay in psycho-motor development in children they say:

• disorganization of the alpha rhythm;
• increased synchronicity and amplitude;
• moving the focus of activity from the nape and crown;
• weak short activation reaction;
• excessive response to hyperventilation.

A decrease in the amplitude of the alpha rhythm, a shift in the focus of activity from the nape and crown of the head, a weak activation reaction indicate the presence of psychopathology.

Excitable psychopathy is manifested by a slowdown in the frequency of the alpha rhythm against the background of normal synchrony.

Inhibitory psychopathy is manifested by EEG desynchronization, low frequency and alpha rhythm index.

Increased synchrony of the alpha rhythm in all parts of the brain, a short activation reaction - the first type of neuroses.

Weak expression of the alpha rhythm, weak activation reactions, paroxysmal activity - the third type of neuroses.

beta rhythm

Normally, it is most pronounced in the frontal lobes of the brain, has a symmetrical amplitude (3–5 μV) in both hemispheres. The pathology of the beta rhythm is the following signs:

• paroxysmal discharges;
• low frequency distributed over the convexital surface of the brain;
• asymmetry between the hemispheres in amplitude (above 50%);
• sinusoidal type of beta rhythm;
• amplitude more than 7 μV.

What do beta rhythm disturbances on the EEG indicate?
The presence of diffuse beta waves with an amplitude of no higher than 50-60 μV indicates a concussion.

Short spindles in beta rhythm indicate encephalitis. The more severe the inflammation of the brain, the greater the frequency, duration and amplitude of such spindles. Observed in a third of patients with herpes encephalitis.

Beta waves with a frequency of 16 - 18 Hz and high amplitude (30 - 40 μV) in the anterior and central departments brain - signs of delayed psychomotor development of the child.

EEG desynchronization, in which the beta rhythm predominates in all parts of the brain - the second type of neurosis.

Theta rhythm and delta rhythm

Normally, these slow waves can only be recorded on the electroencephalogram of a sleeping person. In the waking state, such slow waves appear on the EEG only in the presence of dystrophic processes in the brain tissues, which are combined with compression, high blood pressure, and lethargy. Paroxysmal theta and delta waves in a person in the waking state are detected when the deep parts of the brain are affected.

In children and young people under 21 years of age, the electroencephalogram may reveal diffuse theta and delta rhythms, paroxysmal discharges, and epileptoid activity, which are a variant of the norm and do not indicate pathological changes in brain structures.

What do violations of theta and delta rhythms on the EEG indicate?
Delta waves with high amplitude indicate the presence of a tumor.

Synchronous theta rhythm, delta waves in all parts of the brain, flashes of high amplitude bilaterally synchronous theta waves, paroxysms in the central parts of the brain - speak of acquired dementia.

The predominance of theta and delta waves on the EEG with maximum activity in the back of the head, flashes of bilaterally synchronous waves, the number of which increases with hyperventilation, indicates a delay in the child's psychomotor development.

A high index of theta activity in the central parts of the brain, bilaterally synchronous theta activity with a frequency of 5 to 7 Hz, localized in the frontal or temporal regions of the brain, speak of psychopathy.

Theta rhythms in the anterior parts of the brain as the main ones are an excitable type of psychopathy.

Paroxysms of theta and delta waves are the third type of neuroses.

The appearance of rhythms with a high frequency (for example, beta-1, beta-2 and gamma) indicates irritation (irritation) of brain structures. This may be due to various disorders cerebral circulation, intracranial pressure , migraines, etc.

Bioelectrical activity of the brain (BEA)

This parameter in the EEG conclusion is a complex descriptive characteristic relating to brain rhythms. Normally, the bioelectrical activity of the brain should be rhythmic, synchronous, without foci of paroxysms, etc. In the conclusion of the EEG, the doctor usually writes what kind of violations of the bioelectrical activity of the brain were detected (for example, desynchronized, etc.).

What do various disorders of the bioelectrical activity of the brain indicate?
Relatively rhythmic bioelectrical activity with foci of paroxysmal activity in any area of ​​the brain indicates the presence of a certain area in its tissue, where excitation processes exceed inhibition. This type of EEG may indicate the presence of migraines and headaches.

Diffuse changes in the bioelectrical activity of the brain may be a variant of the norm if no other abnormalities are detected. Thus, if the conclusion says only about diffuse or moderate changes bioelectrical activity of the brain, without paroxysms, foci of pathological activity, or without lowering the threshold of convulsive activity, then this is a variant of the norm. In this case, the neurologist will prescribe symptomatic treatment and put the patient under observation. However, in combination with paroxysms or foci of pathological activity, they speak of the presence of epilepsy or a tendency to convulsions. Reduced bioelectrical activity of the brain can be detected in depression.

Other indicators

Dysfunction of the middle structures of the brain - this is a mild violation of the activity of brain neurons, which is often found in healthy people, and indicates functional changes after stress, etc. This condition requires only a symptomatic course of therapy.

Interhemispheric asymmetry may be a functional disorder, that is, not indicative of pathology. In this case, it is necessary to undergo an examination by a neurologist and a course of symptomatic therapy.

Diffuse disorganization of the alpha rhythm, activation of the diencephalic-stem structures of the brain against the background of tests (hyperventilation, closing-opening of the eyes, photostimulation) is the norm, in the absence of complaints from the patient.

The focus of pathological activity indicates increased excitability of the specified area, which indicates a tendency to convulsions or the presence of epilepsy.

Irritation of various brain structures (cortex, middle sections, etc.) is most often associated with impaired cerebral circulation due to various causes (for example, atherosclerosis, trauma, increased intracranial pressure, etc.).

Paroxysms they talk about an increase in excitation and a decrease in inhibition, which is often accompanied by migraines and just headaches. In addition, a tendency to develop epilepsy or the presence of this pathology is possible if a person has had seizures in the past.

Decreased seizure threshold speaks of a predisposition to convulsions.

The following signs indicate the presence of increased excitability and a tendency to convulsions:

• change in the electrical potentials of the brain according to the residual-irritative type;
• enhanced synchronization;
• pathological activity of the median structures of the brain;
• paroxysmal activity.

In general, residual changes in brain structures are the consequences of damage of a different nature, for example, after trauma, hypoxia, or a viral or bacterial infection. Residual changes are present in all brain tissues, therefore they are diffuse. Such changes disrupt the normal passage of nerve impulses.

Irritation of the cerebral cortex along the convexial surface of the brain, increased activity of the median structures at rest and during tests, it can be observed after traumatic brain injuries, with a predominance of excitation over inhibition, as well as with organic pathology of brain tissues (for example, tumors, cysts, scars, etc.).

epileptiform activity indicates the development of epilepsy and an increased tendency to convulsions.

Increased tone of synchronizing structures and moderate dysrhythmia are not severe disorders and pathology of the brain. In this case, resort to symptomatic treatment.

Signs of neurophysiological immaturity may indicate a delay in the psychomotor development of the child.

Pronounced changes in the residual-organic type with increasing disorganization on the background of tests, paroxysms in all parts of the brain - these signs usually accompany severe headaches, increased intracranial pressure, attention deficit hyperactivity disorder in children.

Violation of the wave activity of the brain (the appearance of beta activity in all parts of the brain, dysfunction of the midline structures, theta waves) occurs after traumatic injuries, and can be manifested by dizziness, loss of consciousness, etc.

Organic changes in brain structures in children are the result of infectious diseases, such as cytomegalovirus or toxoplasmosis, or hypoxic disorders that occurred during childbirth. Necessary comprehensive examination and treatment.

Regulatory cerebral changes recorded in hypertension.

The presence of active discharges in any part of the brain , which increase during exertion, means that in response to physical stress, a reaction may develop in the form of loss of consciousness, impaired vision, hearing, etc. A specific reaction to physical exercise depends on the localization of the source of active discharges. In this case, physical activity should be limited to reasonable limits.

Brain tumors are:

• the appearance of slow waves (theta and delta);
• bilateral-synchronous disorders;
• epileptoid activity.

Changes progress as the volume of education increases.

Desynchronization of rhythms, flattening of the EEG curve develops in cerebrovascular pathologies. A stroke is accompanied by the development of theta and delta rhythms. The degree of electroencephalogram disorders correlates with the severity of the pathology and the stage of its development.

Theta and delta waves in all parts of the brain, in some areas, beta rhythms are formed during injuries (for example, during concussion, loss of consciousness, bruise, hematoma). The appearance of epileptoid activity against the background of a brain injury can lead to the development of epilepsy in the future.

Significant slowing of the alpha rhythm may accompany parkinsonism. Fixation of theta and delta waves in the frontal and anterior temporal parts of the brain, which have different rhythms, low frequency and high amplitude, is possible in Alzheimer's disease and postinfarction dementia. These EEG changes are permanent and are called anterior bradyarrhythmia.

Electroencephalogram: price of the procedure

To date, the cost of taking an electroencephalogram in state medical institutions ranges from 400 to 1,500 rubles. In private medical clinics, the cost of an electroencephalogram may be higher, which is determined by the pricing policy of the institution, the qualifications of the specialist, and other factors.

The most preferred time to perform an EEG is seven days after an attack, since a study conducted immediately after an attack will show not the ailment itself, but changes in the brain caused by an attack. To conduct a long-term electroencephalogram ( more than 30 minutes) portable devices are used, as well as video filming. The combination of these methods makes it possible to fully judge the nature of the attack.

Epileptic seizures can contribute to EEG results various changes. But in the vast majority of cases, these are discharges of generalized waves of different frequencies, while the amplitude of the waves is increased. Such phenomena are explained as convulsive readiness. In children, such changes often disappear on their own as the central nervous system develops. Often, at the end of the course of treatment with phenobarbital, similar electroencephalogram readings are observed.
Generalized seizures are expressed in the EEG as peak-wave complexes, but if epilepsy is focal in nature, such changes are found only in the affected areas of the brain, usually in the temporal regions.

Not every doctor can correctly explain the results of an electroencephalogram. Often, phenomena resembling epileptic discharges accompany pulsation of blood vessels, rotation of the eyeballs, heartbeat, and swallowing.

To detect epilepsy, it is necessary to calculate the presence of a special electrical activity of the brain. To do this, electrodes are attached to the scalp, catching electrical impulses, which are immediately transmitted to the amplifier and “remembered” by the device. While the procedure is taking place, the patient is in a supine position, with lowered eyelids, in a semi-dark room. Such measures are necessary so that the incoming light or other factors do not cause excessive brain activity that affects the EEG. The study time is twenty minutes. If a person suffers from epilepsy, the EEG shows processes called epileptic activity.

It should be said that the detection of epileptic activity on an encephalogram does not yet mean that a person is sick with this disease. According to some reports, ten percent of healthy people with such an examination show such signs in themselves.

At the same time, people suffering from epileptic seizures may have a completely “healthy” encephalogram. With a similar picture, special tests are carried out to detect epilepsy, artificially exciting the brain. There are many methods of artificial excitation. This is a refusal to sleep the day before the examination, photostimulation, hyperventilation.

Hyperventilation is breathing that is faster than normal for several minutes. Such breathing causes the activation of hyperactive areas of the brain.
Photostimulation is carried out by flashes of bright light of a specially selected frequency. Such an effect also provokes an increase in the epileptiform activity of the brain.

According to the EEG, it is quite possible to detect the phases of wakefulness and sleep in an unborn baby during pregnancy from twenty-eight weeks. Sleep mechanisms are gradually improved and by one year they are already fully consistent with human sleep in adulthood ( except for some differences).

There are two stages of sleep - "fast" and "slow". In addition to other signs, one of the main ones for determining each of the phases of sleep is the presence of rotations of the eyeballs. Given this factor, the stages are referred to as REM and Non-REM. Although the EEG in different phases is quite different, for an absolute correct classification, it is necessary to fix eye rotations in different phases (EOG), as well as muscle activity (EMG). Without observing this parameter, it is quite difficult to make an accurate sleep EEG.

Phase Non-REM

• first stage ( drowsiness, sleep) lasts five to ten minutes. The eyeballs rotate slowly. In the EEG, there is a predominance of theta waves, the amplitude of which corresponds to or slightly more than that of the alpha rhythm. In the electroencephalogram, certain characteristic phenomena are found ( sharp vertex waves, hypnagogic hypersynchrony).
• second stage ( stage light sleep ). The muscles relax. Heart rate and body temperature decrease. The eyeballs do not rotate. Theta rhythms are observed in the EEG, and patterns of the second stage are also detected: K-complexes and sleep spindles. This phase of sleep accounts for approximately half of the time spent sleeping. One episode of this phase lasts approximately twenty minutes.
• The third and fourth stages ( NREM sleep, delta). In this phase, sleep is the strongest. The eyeballs do not move. In the EEG, delta-rhythms with a large amplitude are observed in the vast majority.
• In the case when the delta rhythms occupy less than half of the period under consideration, the stage is considered the third, but if the delta rhythms make up more than half, this is already the fourth stage. This stage makes up five to eight percent of the sleep period. The duration of the first period of this phase is from thirty to forty minutes. This phase is characterized by sleepwalking, enuresis.

R.E.M. sleep

• It is characterized by only one stage, in which a person sees dreams that are very distinct and memorable. At this stage of sleep actively rotate eyeballs, there are failures in breathing and heartbeat, blood pressure increases, muscle twitching. On the EEG, alpha and beta rhythms, sawtooth waves are detected. The picture of the electroencephalogram is more similar to the picture of the first phase of sleep. In total, this phase accounts for up to twenty percent of sleep time.

EEG during sleep
According to the results of multiple studies, some types of epilepsy manifest themselves on the encephalogram when performing the procedure while the patient is sleeping. Such an examination makes it possible to determine epileptic disorders in the vast majority of patients in whom the encephalogram does not show epileptic activity during wakefulness, even when special tests are used. However, to conduct such an examination, certain conditions are required, as well as specially trained personnel. Therefore, its application is limited.

EEG monitoring
If the patient suffers from seizures, but their nature cannot be detected, such an examination is performed. This is a rather difficult way. In the course of it, an encephalogram is performed, and at the same time a video recording is carried out. This examination is carried out exclusively in specialized institutions.

brain mapping
This type of examination with simultaneous electronic processing of the results of the activity of brain cells, as well as the issuance in the form of a graph. The use of this method is mainly used for focal disorders caused by epilepsy. Most often, such an examination is carried out in special neurological clinics.

EEG with biofeedback
This method involves obtaining an encephalogram, as usual, which takes place simultaneously with sound and light manifestation. That is, the patient observes his encephalogram and tries to influence its condition. This examination is similar to training on the impact on light and music accompaniment. So you can slightly influence the activity of brain cells and even control certain types of seizures. Therapy by this method is very complex and lengthy. The biofeedback method can be of great help to those patients who are not amenable to anticonvulsant treatment. But this therapy does not exclude the use of drugs.

It is the "control center" of all human activity. It is he who receives and processes the signals coming from the outside world and forms reactions in response to them. This complex and largely unexplored human organ sometimes malfunctions and starts to work incorrectly. There are a lot of medical methods for studying the brain, but often such diagnostic methods as MRI and ultrasound are not able to determine the lesion and establish the causes of its occurrence.

An encephalogram of the brain helps physicians to cope with the diagnostic tasks. What it is, how such a procedure is carried out and how it helps specialists in understanding the causes of brain disorders, we will consider in this article.

What it is?

Most of us are quite calm about such studies as ultrasound and fluorography, but for many, electroencephalography causes fear and a certain distrust. In fact, an encephalogram of the brain is just a method of fixing the electrical impulses of the nerve cells of this organ and its departments. To carry out the procedure, special electrodes are placed on various parts of the subject's head, transmitting information via wires to a computer that displays the bioelectrical activity of the neurons that make up the brain on a screen or builds curves on paper. Even minimal deviations in brain activity are monitored and recorded, which makes it possible to more accurately establish the diagnosis and causes of diseases of this organ.

So, what does the encephalogram of the brain show? The resulting graphical representations demonstrate all its active areas, manifesting themselves in certain rhythms and waves.

The history of the method

After it was established in the middle of the 19th century that the brain, like nerve or muscle fibers, can generate electrical impulses, studies began on the bioelectrical activity of its cells - neurons. For the first time, measurements of the electrophysiological readings of the brain of animals, such as dogs, rabbits and monkeys, were presented in 1875 by two independent researchers: the Englishman Caton and the Russian scientist Danilevsky. The beginning of the science of electroencephalography is considered to be 1913, when the first encephalogram of the dog's brain was recorded by the Russian scientist V.V. Pravdich-Nemitsky. The first "picture" of the work of the human brain was made by the German researcher G. Berger in 1928, who introduced the term "electroencephalogram".

This method of research and diagnosis has been widely used in medical practice since 1934, after the existence of Berger's rhythm was confirmed.

Why is it being carried out?

Such a diagnostic technique as an encephalogram of the brain provides physicians with the following opportunities:

1. Assess the features and depth of disorders of brain functions.
2. Find out the location of the affected area.
3. Determine the causes of various disease states.
4. Clarify the data of other diagnostic methods.
5. Monitor the effectiveness of medications.
6. To study the periodicity of the processes of excitation and inhibition.
7. Identify areas of the brain responsible for the occurrence of epileptic seizures.
8. Track the activity of the human brain during operations on it under general anesthesia.
9. Establish brain viability in coma patients.

Indications for carrying out

An encephalogram of the brain is not prescribed for all patients, but there are a number of diseases and conditions in which doctors consider such a diagnosis necessary:

• traumatic brain injury;
• transferred surgical interventions on the spine and brain;
• testing hypotheses about the presence of neoplasms in the brain;
• symptoms of cerebrovascular accident;
• epilepsy;
• convulsions;
• frequent fainting;
• bouts of behavior unusual for a person;
• neurotic diseases and disorders;
• hypertonic disease;
• osteochondrosis cervical spine;
• sleep disorders;
• delayed speech or mental development.

In addition to the conditions and diseases listed above, from 04/01/2014, according to the changed traffic safety rules, in order to obtain a driver's license or change it, an encephalogram of the brain is required for the traffic police (traffic police) and a psychiatrist's conclusion on it.

How is the procedure carried out?

To register the bioelectrical activity of brain cells, or, as experts say, biopotentials, a special apparatus is needed - an electroencephalograph, thanks to which it becomes possible to fix rather weak biocurrents and amplify them while passing through the device.

As mentioned above, electrical activity is recorded due to special electrode-sensors that are applied and fixed on the patient's head according to special schemes. The data obtained is an encephalogram of the brain, which shows which parts of the brain are active. For further research it is stored electronically or printed on paper. The recording is carried out relative to the so-called zero-potential, which is taken as processus mastoideus ( mastoid temporal bone) or earlobe that do not emit biocurrents.

Features of the

The main condition for conducting an encephalographic study is the complete immobility of the patient throughout the procedure.

If this condition is not met, then the device will detect movements as interference, and they can greatly interfere with the correct interpretation of the readings. Unfortunately, when conducting encephalography in children, it is impossible to avoid interference, and it is quite difficult to simply persuade the kids to put on a helmet with wires and electrodes. As a rule, before the diagnosis, doctors prohibit the use of drugs that affect the functioning of the brain.

Interpretation of the results

The data obtained as a result of encephalography, as a rule, are stored in a computer, which allows you to create a personal database about each patient. Graphically, two types of rhythmic oscillations are displayed: alpha and beta waves.

The latter, whose frequency is approximately 30 per second, and the voltage is about 20 μV, are characteristic of the normal functioning of the brain in wakefulness. It is them that the electroencephalograph fixes. A change in their nature, the appearance of peaks or theta or alpha waves in the waking state indicate the presence of any disease, one or another abnormal process.

This is the question that puzzles most motorists. So, until April 1, 2014, in order to obtain or replace a driver's license, a regular medical certificate with the conclusion of a narcologist and a psychiatrist was required. Now you can only get an appointment with the last specialist if you have the results of an electroencephalographic study in your hands. In order for you to have an encephalogram of the brain for the traffic police (GIBDD), you must undergo an examination in a specialized medical institution where there is the necessary equipment and qualified specialists. There are two possible options for action: through a regular public clinic at the place of residence or a private medical center. In both cases, there are both advantages and disadvantages.

When contacting a polyclinic at the place of residence, you first need to get an appointment with a neurologist, since only he can write you a referral for electroencephalography (EEG). To do this, you will have to make an appointment in advance, wait for a specialist to see you, and go for an examination with a referral. You can try to go directly to a psychiatric dispensary and do a paid EEG there, if such equipment is available there and the service is provided. The most time-consuming option is to immediately go to a commercial organization, but only for this you will have to pay several times more. Today, an encephalogram of the brain in Moscow costs from 400 rubles in state clinics, and from 1,500 rubles in private clinics. The closer to the center of the capital, the higher the price.

Maintaining health is becoming more and more difficult today. There are more and more factors that negatively affect the physical and mental state of a person. Unfortunately, not all of us are able to protect ourselves on our own. Therefore, it is extremely important, if any suspicious symptoms appear, to contact specialists and conduct studies that will help detect the disease at an early stage, while the pathological processes are still reversible. This can help maintain the same quality of life or even save it. Today we will talk about one of these studies - an electroencephalogram. What does she represent? What is the value this study? What is the alpha rhythm, and what role does it play in the functioning of the body? This article will help you understand all this.

Electroencephalogram of the brain

The study in question is a literal record of the activity (namely, electrical) of certain brain structures. The results of the electroencephalogram are recorded on specially designed paper using electrodes. The latter are superimposed on the patient's head in a certain order. Their task is to register the activity of individual parts of the brain. Thus, the electroencephalogram of the brain is a record of its functional activity. The study can be carried out for any patient, regardless of his age. What does the EEG show? It helps to determine the level of brain activity and identify a variety of disorders of the functioning of the central nervous system, including meningitis, polio, encephalitis and others. It also becomes possible to find the source of damage and assess its degree.

When conducting an electroencephalogram, as a rule, the following tests are necessary:

• Blinking of different speed and intensity.
• Exposure of the patient's completely closed eyes to periodic bright flashes of light (the so-called photostimulation).
• Deep breathing (rare inhalations and exhalations) for a period of three to five minutes (hyperventilation).

The tests listed above are conducted for both children and adults. Neither the diagnosis nor the age affects the composition of the test.

Additional studies that the doctor conducts, depending on certain factors, are the following:

• sleep deprivation for a certain time;
• passing a series of psychological tests;
• clenching the palm into a fist;
• monitoring the patient during the entire period of night sleep;
• taking certain medications;
• the patient is in the dark for about forty minutes.

What does an electroencephalogram show?

What is this survey? To find out the answer, it is important to understand in detail what the EEG shows. It demonstrates the current functional state of certain structures that make up the brain. It is carried out under various conditions of the patient, such as wakefulness, active physical work, sleep, active brainwork and so on. The electroencephalogram is an extremely safe way research, painless, simple, one that does not require serious intervention in the work of the body. It allows you to accurately determine the location of cysts, tumors, mechanical damage to brain tissues, to diagnose vascular diseases, epilepsy, inflammatory diseases of the brain and its degenerative lesions.

Where to make it?

Such an examination, as a rule, is carried out in psychiatric dispensaries, neurological clinics, and sometimes in district and city hospitals. Clinics usually do not provide such services. However, it is better to find out directly on the spot. Experts recommend contacting neurology departments or psychiatric hospitals. Local doctors are qualified enough to carry out the procedure in the right way and correctly interpret the results. If we are talking about a small child, then you should contact children's hospitals specially designed for such examinations. Also, a similar service is provided in private medical centers. There are no age restrictions here.

Before going to the examination, you need to get a good night's sleep and spend some time before this day in peace without stress and excessive psychomotor agitation. Alcohol, caffeine, sleeping pills, tranquilizers, anticonvulsants, and sedatives should not be consumed for two days before the EEG.

Electroencephalogram for children

This study should be considered in more detail. After all, as a rule, parents have a lot of questions in this regard. The kid will be forced to spend about twenty minutes in a light and soundproof room, where he lies on a special couch with a cap on his head, under which the doctor places the electrodes. The scalp is additionally moisturized with gel or water. Two electrodes are placed on the ears, which are not active. The strength of the current is so small that it cannot cause the slightest harm even to babies.

The child's head should be level. If the baby is older than three years old, he can stay awake during the procedure. You can take something with you that will distract the child and allow him to calmly wait for the end of the examination. If the patient is younger, then the procedure is performed during sleep. At home, the baby needs to wash his hair and not feed. Feeding is carried out already in the clinic immediately before the procedure, so that he quickly falls asleep.

The frequency of brain alpha rhythms and other rhythms is fixed in the form of a background curve. Additional tests (eg, photostimulation, hyperventilation, rhythmic closing and opening of the eyes) are also often performed. They are suitable for everyone: both children and adults. So, deep breaths and exhalations can reveal latent epilepsy. Ancillary studies help to find out the presence or absence of a delay in the development of the baby (speech, mental, mental or physical development).

Electroencephalogram rhythms

This survey allows you to evaluate the following types of brain rhythms:

• alpha;
• theta rhythm;
• beta;
• delta.

Each of them has certain characteristics and helps to evaluate different types of brain activity.

• The normal frequency of the alpha rhythm is in the range from 8 to 14 Hz. This should be taken into account when determining pathologies. The considered alpha EEG rhythm registers when the patient is awake, but his eyes are closed. As a rule, this indicator is regular. It registers most quickly in the region of the crown and occiput. In the presence of any motor stimuli, it stops.
• The frequency of the beta rhythm ranges from 13 to 30 Hz. As a rule, it is registered just above the frontal lobes. Characterizes the state of depression, anxiety, anxiety. It also reflects the fact of the use of sedatives.
• Normally, the theta rhythm has an amplitude of 25 to 35 microvolts, and a frequency of 4 to 7 Hz. Such indicators reflect the state of a person when he is in a state of natural sleep. For the child, the considered rhythm is prevailing.
• The delta rhythm in most cases demonstrates the state of natural sleep, but during wakefulness it can be registered to a limited extent. The normal frequency is 0.5 to 3 Hz. The normal value of the rhythm amplitude does not exceed 40 μV. Deviations from these values ​​indicate the presence of pathologies and impaired functioning of the brain. By the location of the appearance of a rhythm of this type, it is possible to determine exactly where dangerous changes occur. If it is noticeable in all areas of the brain, this indicates a violation of consciousness and that a systemic lesion of the structures of the central nervous system is developing. The reason for this is often liver dysfunction.

Significance for the body

The alpha rhythm of the brain becomes monitored only in moments of calm and is low-frequency. Then the parasympathetic system is activated. Being in the alpha state, the central nervous system, figuratively speaking, reboots and gets rid of all the stress that has been accumulated during the day. Alpha rhythm provides regular recovery of the body, as well as the accumulation necessary resources after working period. As history shows, a huge number of amazing discoveries were made by people during their periods in the state in question. What else should you know?

Functions

What is the function of alpha rhythms?

• Leveling the effects of stress (lowered immunity, constriction of blood vessels).
• Analysis of all the information that was received by the brain during the day.
• Excessive activity of the limbic system is not allowed.
• The circulation of the brain improves significantly.
• All resources of the organisms are restored, spurred on by the activation of the parasympathetic system.

How does alpha rhythm disturbance affect daily life? Patients in whom the generation of alpha waves is significantly reduced, as a rule, are more likely to go in cycles in their own problems, they tend to think negatively. Such disorders lead to a decrease in immunity, the development of various cardiovascular diseases and even oncology. Often there are malfunctions in the work of the glands that synthesize hormones, irregularity menstrual cycle, the development of a variety of addictions and a tendency to various kinds of abuse (for example, alcoholism, drug addiction, overeating, smoking).

A well-established alpha rhythm ensures the normal course of regenerative processes in body tissues. It plays a vital role in maintaining the life of the individual.

Norm and pathology

An electroencephalogram helps to identify and evaluate the index, which characterizes the alpha rhythm of the brain. Its rate fluctuates between 75% and 95%. If its significant decrease (less than 50%) is noted, then we can safely talk about pathology. The considered rhythm, as a rule, is markedly reduced in the elderly (over 60 years). The reason for this is usually age-related disorders of cerebral circulation.

Another striking indicator is the amplitude of the rhythm. Its normal value is considered to be waves with an amplitude of 20 to 90 μV. The asymmetry of both this indicator and the rhythm frequency in different hemispheres indicates the presence of a number of diseases, such as narcolepsy, epilepsy, or essential hypertension. A low frequency indicates hypertension, and an increased frequency indicates oligophrenia.

If the rhythms are not synchronized, it is also important to perform additional tests to clarify the pathology. Narcolepsy is characterized by hypersynchrony. Asymmetry also indicates a possible traumatic injury to the corpus callosum, as well as the presence of a tumor or cyst. The complete absence of the alpha rhythm occurs with blindness, developing Alzheimer's disease (the so-called acquired dementia) or cerebral sclerosis. Problematic indicators can occur in violation of cerebral circulation.

Patients with what conditions and symptoms would also benefit from the examination in question? EEG indications are frequent vomiting, osteochondrosis, frequent fainting, brain injuries and tumors, high blood pressure, headaches, suspected dementia (both acquired and congenital), as well as vegetovascular dystonia. Only a qualified neurologist can prescribe a study and decipher the results.

What do the indicator violations indicate?

Depending on how the alpha rhythm is disturbed, a specific disease is determined. So, for example, if it is disorganized or absent in principle, then the diagnosis is acquired dementia. Interhemispheric asymmetry of the alpha rhythm indicates the presence of a heart attack, cyst, stroke, tumor or scar, indicating an old hemorrhage. Close attention should be paid to this. An unstable rhythm or a high-frequency alpha rhythm of the brain can be a manifestation of traumatic injury.

As for children, the following disorders indicate a delay in their development:

• Abnormally pronounced reaction to hyperventilation.
• The alpha rhythm is disorganized.
• The concentration of activity has been moved from the region of the crown and back of the head.
• The amplitude of the alpha rhythm and synchrony are noticeably increased.
• The activation reaction is short and weak.

Psychopathology in adults can also be expressed by a low amplitude of the rhythm, a weak activation reaction, as well as a shift in the concentration point of activity from the region of the crown and back of the head.

Conclusion

An electroencephalogram is a safe and painless test that helps identify a number of dangerous diseases. The study can be carried out even on infants. It allows you to evaluate the nature of the rhythms of the brain. By interpreting the information received and prescribing the correct treatment, a specialist neuropathologist will help you cope with the symptoms that bother you.

In order to avoid encountering such problems, it is necessary to carry out appropriate diagnostics in the presence of alarming symptoms. Electroencephalography, a fairly common type of brain study, occupies a high bar in the list of the most important procedures. EEG preparation has a number of significant features that require special attention.

A brief introduction to the 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 registers the level of coordination of actions of all components. brain department(or property of rhythm). If a person’s central nervous system has been attacked by a particular ailment, diagnostics will reveal a violation in the work of the organ.

The test is not particularly difficult. The patient is comfortably located on the equipped couch in a semi-lying position. Certain points of the head are treated with a gel that provides impulses, and small electrodes are attached to the surface. When diagnosing, a person must relax the muscles and cover the eyelids.

Next starts computer program, which registers brain activity with the help of sensors 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 in a few days.

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

With the help of EEG it is possible to detect:

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

Indications and contraindications

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

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

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

Special contraindications have not 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, the presence of sutures that have not yet healed, applied surgically.

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, the diagnosis should be carried out only under the close supervision of a qualified physician.

The order of preparation for the 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 correct result of brain research.

Sometimes the patient is assigned an EEG in the dreaming phase. In this case, a prerequisite is the lack of sleep for hours. The body should not be "slept" at the time of direct testing of the brain.

EEG cost

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

An electroencephalogram of the brain is able to detect pathologies of the central nervous system or, conversely, exclude them. Despite the relative ease of diagnosis, do not neglect the code elementary rules EEG preparation. Remember: only the correct observance of each item to the proper extent will ensure a good examination result and, as a result, indicate a clear direction for the vector of therapeutic therapy.

Comments

You can do an EEG at any clinic for a psychiatrist or just where he sends

EEG can be done in any suitable hospital

How to cheat an EEG

I want to get a disability for the evil of the state, for being called by force (caught on the street) when I was studying at a university and now I have no diploma, no health (there are many other ailments), no compensation.

It is possible that you can somehow hide the battery from the watch in your mouth. The ECG knocks it down for sure. But now, before checking, they lie in everyone's mouth. How it affects the EEG - who knows, but it probably won't be a plus.

Legal chemicals that suppress nervous activity. Sleeping pills, for example. Probably and exciting somehow influence - eleoterakok.

Electroencephalography

Electroencephalography (EEG) is a method for studying the functioning of the brain, based on the registration of electrical impulses emanating from its individual zones and regions. Such diagnostics has practically no contraindications; is fundamental for the detection of epilepsy and some other pathologies of the brain. Electroencephalography (EEG) requires preliminary preparation. The result is deciphered jointly by the doctor conducting the study (neurophysiologist) and the neuropathologist 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 coordinated within small regions of the brain; can reinforce or weaken each other. The strength and amplitude of these microcurrents are not stable, but must change.

This electrical (it is called bioelectrical) activity of the brain can be registered using special metal electrodes applied to the intact scalp. They pick up brain vibrations, amplify them, and record them as various vibrations. This is called electroencephalography, and for a person initiated into this "cipher" it is a graphical representation 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, mu waves.

What is an EEG for?

Diagnostics allows you to:

• assess the nature and degree of brain dysfunction;
• to study the change of sleep and wakefulness;
• establish 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 drugs;
• find areas of the brain in which epileptic seizures begin;
• evaluate how the brain works between periods of seizures;
• identify the causes of crises, panic attacks, fainting.

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

Indications

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

EEG is shown at:

• insomnia;
• sleep disorders (sleepwalking, sleep speaking, sleep apnea);
• convulsive attacks;
• identified endocrine diseases;
• craniocerebral injuries;
• pathologies of the vessels of the head and neck (identified by ultrasound);
• encephalitis, meningitis;
• vegetative-vascular dystonia;
• after a stroke or microstroke;
• frequent headaches;
• dizziness;
• feeling of constant fatigue;
• after a neurosurgical operation;
• 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 in a dream.

Contraindications

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

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

Training

It is not necessary to follow a certain diet, starve or cleanse the intestines before an EEG, but the study is carried out after observing several rules for preparing for it:

1. Whether or not to cancel the planned intake of drugs, the doctor must decide. This should be discussed with him in advance.
2. 12 hours before the examination, you need to stop taking foods containing caffeine or energy drinks: coffee, chocolate, tea, cola, energy drinks.
3. Wash your hair, do not apply any products (varnishes, 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, it is impossible to be nervous and worried during the study.
6. If the doctor needs to check for 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 can not get to the medical institution while driving.
7. Do not undergo a study with SARS.
8. Do not perform the examination with hair on the 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 the pool, sports), serving it in the form of a game of pilots, tankers, divers;
• practice deep breathing;
• wash your hair, do not braid your hair, remove earrings;
• before leaving the child to feed and soothe;
• take with you delicious food and drink, toys and books (to calm, distract from the procedure).

The course of the procedure

This type of diagnosis is usually carried out in daytime, but sometimes the EEG of sleep is more informative.

The patient goes to 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 a camera.

Several times the patient is asked to close and open his eyes in order to assess the artifacts that appear on the encephalogram during blinking. During the examination, the eyes remain closed.

If, at any point in the procedure, the person needs to change position or go to the toilet, the person informs the researcher. Diagnostics is suspended.

Various tests can be used to diagnose latent epilepsy:

1. With a flash of bright light;
2. With monotonous on-off light;
3. With hyperventilation, for which the patient is asked to take deep breaths several times (against this background, the head may feel dizzy, but this stops as soon as he breathes normally);
4. With loud sound;
5. With falling asleep - independent 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 in the daytime. After its completion, a 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 medical institutions, the cost of conducting a study is rubles. Private medical centers in Moscow, for example, NEARMEDIC, SM-Clinic, Dobromed, Mental Health and others offer this diagnostic for rubles.

Video of the procedure:

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

Comments

After encelography of the brain of my child, immaturity was written in the conclusion, I wanted to know why and whether it would pass.

Electroencephalography of the brain: a technique for conducting

Electroencephalography (EEG) is a method of studying the activity of the brain by recording electrical impulses emanating from various areas of the brain. This diagnostic method is carried out by means of a special device, an electroencephalograph, and is highly informative in relation to many diseases of the central nervous system. You will learn about the principle of electroencephalography, indications and contraindications for its implementation, as well as the rules for preparing for the study and the methodology for conducting it from our article.

What is an EEG

Everyone knows that our brain consists of millions of neurons, each of which is able to independently generate nerve impulses and transmit them to neighboring nerve cells. In fact, the electrical activity of the brain is very small and amounts to millionths of a volt. Therefore, in order to evaluate it, it is necessary to use an amplifier, which is what an electroencephalograph is.

Normally, impulses emanating from different parts of the brain are coordinated within its small areas; under different conditions, they weaken or strengthen each other. Their amplitude and strength also vary depending on external conditions or the state of activity and health of the subject.

All these changes are quite within the power to register the electroencephalograph device, which consists of a certain number of electrodes connected to a computer. Electrodes installed on the patient's scalp pick up nerve impulses, transmit them to a computer, which, in turn, amplifies these signals and displays them on a monitor or on paper in the form of several curves, the so-called waves. Each wave is a reflection of the functioning of a certain part of the brain and is indicated by the first letter of its Latin name. Depending on the frequency, amplitude and shape of the oscillations, the curves are divided into α- (alpha), β- (beta), δ- (delta), θ- (theta) and μ- (mu) waves.

Electroencephalographs are stationary (allowing research to be carried out exclusively in a specially equipped room) and portable (allowing diagnostics directly at the patient's bedside). The electrodes, in turn, are divided into plate (they look like metal plates with a diameter of 0.5-1 cm) and needle.

Why do an EEG

Electroencephalography registers some conditions and gives the specialist the opportunity to:

• to detect and evaluate the nature of brain dysfunction;
• determine in which area of ​​the brain the pathological focus is located;
• detect epileptic activity in a particular part of the brain;
• to evaluate the functioning of the brain in the period between seizures;
• find out the causes of fainting and panic attacks;
• make a differential diagnosis between organic pathology the brain and its functional disorders if the patient has symptoms characteristic of these conditions;
• evaluate the effectiveness of therapy in the case of a previously established diagnosis by comparing the EEG before and during treatment;
• evaluate the dynamics of the rehabilitation process after a particular disease.

Indications and contraindications

Electroencephalography makes it possible to clarify many situations related to the diagnosis and differential diagnosis of neurological diseases, therefore this research method is widely used and positively evaluated by neurologists.

So, EEG is prescribed for:

• disorders of falling asleep and sleep (insomnia, somnambulism, obstructive sleep apnea syndrome, frequent awakenings in a dream);
• seizures;
• craniocerebral injuries;
• neuro-circulatory dystonia;
• frequent headaches and dizziness;
• diseases of the meninges: meningitis, encephalitis;
• acute disorders of cerebral circulation;
• brain tumors;
• recovery after neurosurgical operations;
• fainting (more than 1 episode in history);
• panic attacks;
• constant feeling of fatigue;
• diencephalic crises;
• autism;
• delayed speech development;
• mental retardation;
• stuttering
• tics in children;
• down syndrome;
• suspicion of brain death.

As such, there are no contraindications to electroencephalography. Diagnostics is limited by the presence of skin defects (open wounds), traumatic injuries, recently applied, non-healed postoperative sutures, rashes, and infectious processes in the area of ​​the proposed electrode installation.

Caution should be taken in patients with mental illness, as they may not always be able to follow the doctor's instructions correctly (in particular, to be during the procedure with their eyes closed and not move), as well as violent patients, since they have both the apparatus itself and a cap with electrodes can even cause a feeling of rage. If it is necessary to conduct an EEG in such patients, they are pre-administered sedatives, which at the same time distort the results of the study, that is, make it less informative.

Not every diagnostic department has a portable electroencephalograph in its arsenal, therefore, in such a situation, patients with cardiovascular pathology in its later stages, as well as patients with limited motor capabilities, may become a contraindication to the study. Transporting them to the diagnostic department may have a higher risk than refusing this research method when making a neurological diagnosis.

Do I need to prepare for an EEG?

In order for the study to go smoothly and the result to be as informative as possible, the patient should follow a few simple recommendations before the EEG.

• First of all, it is necessary to inform the attending physician about the drugs that the patient is taking on an ongoing basis or in a course, but precisely during this period of time. Some of them (in particular, tranquilizers, anticonvulsants) can affect brain activity, thereby distorting the results, so the doctor will probably suggest that the patient stop taking them 3-4 days before the study.
• On the eve of the study and on the day of it, do not eat foods that contain caffeine or energy substances - tea, coffee, chocolate, energy drinks and others. They will have an exciting effect on the patient's nervous system, which will distort the EEG result.
• Before the procedure, thoroughly wash your hair, cleaning your hair from the remnants of styling foam, varnish and other cosmetics. Do not use oils and hair masks, since the fat contained in their composition will worsen the contact of the electroencephalograph electrodes with the scalp.
• Eat a full meal a few hours before the test. Lack of food intake will lead to hypoglycemia (low blood sugar), which will also affect the EEG.
• In the process of diagnosis, one should not be nervous, but should be as calm as possible.
• If the patient is assigned a sleep EEG, the night before the study should be sleepless for him. Just before the EEG, he receives sedative drug, which will help him fall asleep during the recording of the electroencephalogram. A sleep EEG is generally needed for people with epilepsy.
• If the purpose of electroencephalography is to confirm brain death in a patient, the doctor should morally prepare relatives for a possible disappointing result and, if necessary, involve a psychologist or psychotherapist to work with them.

The greatest difficulty is the conduct of electroencephalography in children (especially early and preschool) age. The kid is often frightened of the "hat" that a man in a white coat is trying to put on his head. In addition, it is very difficult to convince the child to keep his eyes closed during the study and sit still - without moving. If the child still needs an EEG, the doctor should explain to his parents what points to pay attention to when preparing (including psychological) a son or daughter for the study:

• convince the child that an absolutely safe and painless procedure awaits him, explain to him in an accessible language its essence;
• in a playful way, practice putting on a swimming cap (you can present this as a game, for example, in divers);
• by personal example, show the child how to breathe deeply, let him do it himself, agree with him to repeat the same thing in the doctor's office when he or you ask;
• wash your hair well, do not do complex hairstyles (to quickly let your hair down), remove earrings, if any;
• fully feed before going out;
• do not forget to take your favorite toy and book with you, as well as some goodies - food and drink; in case you have to wait before the EEG, the child can be distracted so that he does not think about the upcoming study and is not afraid of it.

Research methodology

The diagnostic time varies depending on the goals. More often it is carried out in the morning or afternoon, but in some cases it is required to determine the electrical activity of the brain directly during sleep.

The study is carried out in a specially equipped room, protected from noise and light. Only the patient and the doctor are present in the office, but in some clinics even the doctor is outside, maintaining contact with the patient through a video camera and microphone. When conducting EEG child one of his parents must also be in the office.

The patient sits comfortably in a chair or lies on a couch. A special “cap” is put on his head: electrodes connected to each other by a network of wires. Start research.

First, in order to assess the nature of artifacts (technical errors) from blinking, the doctor asks the subject to close and open his eyes several times. Having considered this question completed, he invites the patient to close his eyes and sit / lie still without making any movements. The study is carried out for a short time, therefore, as a rule, it is not difficult for an adult patient to fulfill this diagnostic condition. If the subject really needs to change the position of the body or, for example, wants to go to the toilet, the EEG recording is temporarily stopped. In the case when, during the EEG recording, the patient still moved, or blinked, or made a swallowing movement, the doctor makes an appropriate mark on the film or in the computer - these actions of the subject can affect the nature of the curve, and the doctor, in the absence of a mark about them, can misinterpret them, which will affect the conclusion.

When the resting EEG is recorded, the patient undergoes so-called stress tests to assess the brain's response to stressful situations for him:

• hyperventilation test: the specialist asks the subject to breathe deeply often for 3 minutes; such actions in a predisposed patient can provoke both an attack of generalized convulsions and an absence seizure;
• photostimulation: the test is carried out using a stroboscopic light source that flashes at a frequency of 20 times per second; thus, the reaction of the brain to bright light is evaluated; in predisposed persons, in response to blinking, myoclonic convulsions or an epileptic seizure occur.

The specialist who conducts the study must be prepared for the development of a pathological reaction of the patient's body to provocative tests and have the opportunity and appropriate skills to provide him with emergency care.

At the end of the study, the patient should be reminded of the need to resume taking medications that were canceled before the EEG.

Concluding the article, I would like to repeat that electroencephalography is a painless and highly informative method for diagnosing diseases of the central nervous system. It is indicated for a variety of neurological conditions and, choosing between whether or not it is worth doing it, it is more correct to opt for the first one: if there is no pathology, you will once again be convinced of this and calm down, and if certain changes are found on the EEG a correct diagnosis will be made faster and you will start receiving the right treatment.

Clinic "Good Doctor", clinic specialist Yulia Krupnova talks about electroencephalography:

How to pass the eeg without finding anything

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An electroencephalogram allows you to establish an accurate diagnosis and the causes of brain dysfunction in just a few minutes. The primary source of problems can be acquired or hereditary epilepsy, previous traumatic brain injury, excessive workload, stress and no rash.

The patient in such cases may experience frequent headaches and migraines, high or low blood pressure, constriction of the temples, pain in the eyes, seizures of varying severity. EEG can be used to establish an objective cause and understand whether discomfort is associated with brain disorders.

Rules for preparing for an electroencephalogram

Before doing an EEG of the brain, it is necessary to properly prepare for the procedure. Only if the rules described below are observed, you can count on obtaining accurate data, and hence a reliable diagnosis. In many ways, the interpretation of the obtained indicators depends on the knowledge and experience of the encephalographer. Real neurology specialists work at the Longevity Clinic. You can rely on them and not worry about the results.

EEG preparation includes:

• thorough washing of the head on the eve of the procedure (the cleaner the patient's head and hair, the better the contact of the device with the brain, and the more reliable the data will be);
• the regularity of taking medications prescribed by a doctor (if you refuse to take drugs or take a “break”, the brain may give backlash, provoke an attack);
• a full breakfast / lunch (you can’t come to the procedure hungry, as this again can cause a strange brain reaction and distort the indicators);
• relaxation and calmness (during the EEG, it is important to relax, feel confident and calm, not be afraid of anything and try not to worry).
• During the procedure, you will be given various noises, claps, knocks, sounds of different tonality. There is no need to be afraid of this, since all of them are aimed at identifying the response of the brain and analyzing reactions. Reading information during an attack or immediately after a cerebral hemorrhage or traumatic brain injury is considered especially important and useful.

On the website of the clinic "Longevity" you can find out more detailed information about electroencephalography, appointments for it and consultations with a neuropathologist. After the examination session, a specialist consultation is provided free of charge. EEG has no contraindications and side effects, does not cause pain or serious discomfort.

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One comment on “How to properly prepare for an EEG?”

1. ilya December 4th,:08

How many days to wait for the EEG results?

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Electroencephalography (EEG): the essence of the examination, which reveals, conducting, 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 the 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 - encephalography.

Electroencephalography or EEG is a method of studying the brain (GM) 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 GM (frequency, amplitude), and this is done using electrodes attached in different places on the surface of the head.

What kind of study is an EEG?

Periodically coming convulsive seizures, occurring in most cases with total loss consciousness, popularly referred to as epilepsy, which official medicine calls epilepsy.

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

The 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 fixes them on paper in the form of a broken line, very reminiscent of an ECG.

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

• Thalamus, which oversees and redistributes information;
• ARS (activating reticular system), the nuclei of which, settled in various parts of the GM (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 apparatus where the recording takes place (a graphic image is an encephalogram). Information processing and analysis are the tasks of computer software that “knows” the norms of the biological activity of the brain and the formation of biorhythms depending on age and a specific situation.

For example, routine EEG captures the formation of pathological rhythms during an attack or in the period between seizures, sleep EEG or nighttime EEG monitoring shows how the biopotentials of the brain change during immersion in the world of dreams.

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

1. Are there foci of increased convulsive readiness of GM, and if they are, in what area are they located;
2. At what stage is the disease, how far has it gone or, on the contrary, has begun to regress;
3. What effect does the chosen medicine give and whether its dose is correctly calculated;

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

Features of the EEG in children

What can we say about babies, if some adults, having received an EEG referral, begin to ask what and how, because they doubt the safety of this procedure. Meanwhile, it actually cannot bring any harm to the child, but it is really difficult to make an EEG for a small patient. Babies under one year of age measure the bioelectrical activity of the brain during sleep, before that they wash their hair, feed the baby and, without deviating from the usual schedule (sleep / wakefulness), adjust the procedure to the child's sleep.

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

Preparations for visiting the appropriate office should be started a few days in advance, turning the future trip into a game. You can try to interest the baby in a pleasant journey, 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, do not cry or talk). Unfortunately, such restrictions are very difficult for young children to endure, because they still cannot understand the seriousness of such an event. Well, in such cases, the doctor is looking for an alternative ...

Indications for daytime sleep encephalography or nocturnal EEG in a child are:

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

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

Various 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 reveals the causes of paroxysmal conditions, a short (≈ 15 min) routine method of recording an encephalogram is used, which involves the use of provocative tests to identify hidden disorders - the patient is asked to breathe deeply (hyperventilation), open and close his eyes, or give light stimulation (photostimulation);
2. If the routine EEG did not provide the necessary information, then the doctor prescribes encephalography with deprivation (deprivation of sleep at night in whole or in part). In order to conduct such a study and obtain reliable results, a person is either not allowed to sleep at all, or they wake him up 2-3 hours before the subject’s “biological alarm clock rings”;
3. A long-term EEG recording with registration of the bioelectrical activity of the GM cortex during the “quiet hour” (EEG of sleep) takes place if the doctor suspects that changes in the brain occur during the stay in the “sleep mode”;
4. Experts consider the night EEG to be the most informative, the recording of which is carried out in a hospital. They begin the study while still awake (before going to bed), continue when immersed in a nap, capture the entire period of night sleep and end after a natural awakening. If necessary, the registration of the bioelectrical activity of the GM is supplemented by the application of supernumerary electrodes and the use of video recording equipment.

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

Time and equipment form the price

In other cases, there is a need to measure the GM biopotentials at the time of an attack. In pursuit of such goals, the patient, as well as for conducting a night EEG, is sent to a hospital for hospitalization, where daily EEG monitoring is carried out using audio and video equipment. Continuous EEG monitoring with video recording during the day makes it possible to verify the epileptic origin of paroxysmal memory disorders, isolated auras, as well as episodically occurring psychomotor phenomena.

Electroencephalography is one of the most available methods brain research. And for the price too. In Moscow, you can find this study for 1,500 rubles, and for 8,000 rubles (EEG sleep monitoring for 6 hours), and for 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 specialized clinic neurological profile, where in doubtful cases there is the possibility of a collegial diagnosis (in such institutions, many specialists can encrypt the EEG), as well as get a doctor's consultation immediately after the test or quickly resolve the issue regarding other methods of brain research.

About the main rhythms of the electrical activity of the GM

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

The electroencephalogram is composed of various complex biorhythms emanating from the electrical activity of the GM in different periods of time, depending on specific situations.

At decoding EEG First of all, pay attention to the main rhythms and their characteristics:

• Alpha rhythm (frequency - in the range from 9 to 13 Hz, amplitude of oscillations - from 5 to 100 μV), which is present in almost all people who do not make claims to their health during inactive wakefulness (relaxation during rest, relaxation, shallow meditation). As soon as a person opens his eyes and tries to visualize 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, activation of autonomic nervous activity;
• The beta-rhythm (the frequency is in the range from 13 to 39 Hz, the amplitude of oscillations is up to 20 μV) is not only the mode of our wakefulness, the β-rhythm is characteristic of active mental work. In the normal state, the severity of β-waves is very weak, their excess indicates an immediate reaction of the GM to stress;
• Theta-rhythm (frequency - from 4 to 8 Hz, amplitude is within µV). These waves do not reflect a pathological change in consciousness, for example, a person is dozing, is in a half-sleep, in the stage of superficial sleep, he already sees 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 theta rhythm is observed during prolonged psycho-emotional stress, mental disorders, twilight states, characteristic of some neurological diseases, asthenic syndrome, concussion of the brain;
• Delta rhythm (frequency is in the range from 0.3 to 4 Hz, amplitude - from 20 to 200 μV) - is characteristic of deep immersion in 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 vibrations pass through the cerebral cortex: gamma rhythms reaching a high frequency (up to 100 Hz), kappa rhythms that form in the temporal leads during active mental activity, and mu rhythms associated with mental stress. These waves are not particularly interesting in the diagnostic sense, since they occur with a significant mental load and intense "thought work" that requires a high concentration of attention. The electroencephalogram, as you know, is recorded, although during wakefulness, but in a calm state, and in some cases night monitoring of the EEG or EEG of sleep is generally prescribed.

Video: alpha and beta rhythms on the EEG

EEG decoding

main EEG leads and their designations

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

• In the occipito-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 of more 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 referred to as normal variants.

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

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, showing all clinical symptoms pathology at the time of a seizure. Moreover, paroxysmal manifestations in other cases can be recorded in people who are absolutely healthy, who do not have any signs and 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”), one cannot completely exclude epilepsy from the results of a single test if there are clinical signs of the disease. It is necessary to examine the patient for this unpleasant disease by other methods.

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

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

If the origin of the GM lesion is established, and diffuse changes are recorded on the EEG, then the diagnostic value of this study, although not so significant, still allows you to find one or another disease that is far from epilepsy:

• Meningitis, encephalitis (especially those caused by herpes infection) - on the EEG: periodic formation of epileptiform discharges;
• Metabolic encephalopathy - on the encephalogram: the presence of "three-phase" waves or diffuse slowdowns in rhythm and outbreaks of symmetrical slow activity in the frontal areas.

Diffuse changes on 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 present any complaints and consider themselves absolutely healthy. It also happens, and if there are no clinical manifestations of pathology, then there is no reason for concern either. Perhaps at the next examination, the EEG record will reflect the full norm.

When is an EEG helpful in making a diagnosis?

Electroencephalography, revealing the functional capabilities and reserves of the central nervous system, has become the standard for studying the brain; doctors consider it appropriate to conduct it in many cases and under 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 - according to the situation);
2. With various sleep disorders (insomnia, drowsiness, frequent nocturnal awakenings, etc.);
3. In the presence of convulsions and epileptic seizures;
4. To confirm or rule out complications inflammatory processes caused by neuroinfection;
5. With vascular lesions of the brain;
6. After TBI (brain contusion, concussion) - EEG shows the depth of suffering of the GM;
7. To assess the severity of the consequences of exposure to neurotoxic poisons;
8. In the case of the development of an oncological process affecting the central nervous system;
9. With mental disorders of various kinds;
10. Conduct EEG monitoring in assessing the effectiveness of anticonvulsant therapy and the selection of optimal dosages of therapeutic agents;
11. The reason for doing an EEG may be signs of dysfunction of brain structures in children and a suspicion of degenerative changes in the nervous tissue of the GM in the elderly (dementia, Parkinson's disease, Alzheimer's disease);
12. Patients who are in a coma need an assessment of the state of the brain;
13. In some cases, research is required surgical operations(determination of the depth of anesthesia);
14. How far neuropsychiatric disorders have gone in hepatocellular insufficiency (hepatic encephalopathy), as well as in other forms of metabolic encephalopathies (renal, hypoxic), encephalography will help to recognize;
15. All drivers (future and current) when passing a medical examination to obtain / replace rights are offered to pass an EEG for a certificate provided by the traffic police. The survey is available in the application and easily identifies completely unfit for management vehicles, so it was adopted;
16. Assign electroencephalography to conscripts with a history of convulsions (based on medical records) or in case of complaints of seizures with loss of consciousness accompanied by convulsions;
17. In some cases, such a study as an EEG is used to ascertain the death of a significant part of nerve cells, that is, brain death (we are talking about situations where they say that “a person most likely turned into a plant”).

Video: EEG and epilepsy detection

The study does not require special preparation

EEG does not require special preparation, however, some patients are frankly afraid of the upcoming procedure. Is it a joke - sensors with wires are placed on the head, which read "everything that is happening inside cranium” 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, 12 are enough for a small child.

Meanwhile, I would like to reassure especially suspicious patients: the study is absolutely harmless, has no restrictions on the frequency of conduct and age (at least several times a day and at any age - from the first days of life to extreme 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 well and dries, but does not use any chemicals for styling hair (gel, foam, varnish). Metal objects used for decoration (clips, earrings, barrettes, piercings) are also removed before an EEG is taken. Besides:

• For 2 days they refuse alcohol (strong and weak), do not use drinks stimulating the nervous system, do not regale themselves with chocolate;
• Before the study, they receive advice from a doctor regarding the medications taken (hypnotics, tranquilizers, anticonvulsants, etc.). It is possible that individual drugs, having agreed with the attending doctor, will have to be canceled, and if this cannot be done, then you should inform the doctor who will decipher the encephalogram (mark in the referral form) so that he has in mind these circumstances and takes them into account when drawing up the conclusion.
• 2 hours before the examination, patients should not allow themselves a hearty 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 disease, as well as with coughing and nasal congestion, even if these signs do not belong to an acute process.

When all the rules of the preparatory stage are observed, certain moments are taken into account, the patient is seated in a comfortable chair, the points of contact of the head surface 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 has started ... 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 provoking epileptic activity (deep breathing, opening and closing of the eyes, sleep, light irritation, sleep deprivation) activate the electrical activity of the GM cortex, the electrodes pick up the impulses sent by the cortex and transmit it 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 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.