Encephalogram description. What does an encephalogram of the brain show? What can you find out with an EEG?

Electroencephalography (EEG) is a method of studying brain activity by recording electrical impulses emanating from different areas of the brain. This diagnostic method is carried out using a special device, an electroencephalograph, and is highly informative regarding 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 in our article.

What is EEG

Everyone knows that our brain consists of millions of neurons, each of which is capable of independently generating nerve impulses and transmitting them to neighboring nerve cells. In fact, the electrical activity of the brain is very small, amounting to millionths of a volt. Therefore, 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 consistent within small areas of the brain; 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 capable of being registered by an 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, so-called waves. Each wave is a reflection of the functioning of a specific part of the brain and is designated by the first letter of its Latin name. Depending on the frequency, amplitude and shape of the vibrations, the curves are divided into α- (alpha), β- (beta), δ- (delta), θ- (theta) and μ- (mu) waves.

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

Why do an EEG?

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

• detect and evaluate the nature of brain dysfunction;
• determine in which area of ​​the brain the pathological focus is located;
• found in one or another part of the brain;
• assess brain function between seizures;
• find out the causes of fainting and panic attacks;
• carry out a differential diagnosis between organic pathology of 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 EEG before and during treatment;
• assess 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 assessed by neurologists.

So, EEG is prescribed for:

• disorders of falling asleep and sleep (insomnia, obstructive sleep apnea syndrome, frequent awakenings during sleep);
• seizures;
• frequent headaches and dizziness;
• diseases of the lining of the brain: , ;
• recovery after neurosurgical operations;
• fainting (more than 1 episode in history);
• constant feeling of fatigue;
• diencephalic crises;
• autism;
• delayed speech development;
• mental retardation;
• stuttering;
• tics in children;
• Down syndrome;
• suspected brain death.

There are no contraindications to electroencephalography as such. Diagnostics are limited by the presence of skin defects (open wounds), traumatic injuries, recently applied, unhealed postoperative sutures, rashes, and infectious processes in the area where electrodes are supposed to be installed.

Questions are answered by diagnosticians with extensive experience in conducting research.

EEG (Electroencephalogram) is a method that records its activity. It helps detect inflammation, epilepsy and tumors. The method makes it possible to carry out diagnostics in cases where the patient is unconscious. It does not cause harm to adults or children.

Thanks to metal electrodes that are placed on the head, the EEG records brain fluctuations and shows them graphically. More accurate data are those taken before going to bed at night or during sleep.

In terms of time, an EEG of the brain lasts 60 minutes, but in problematic cases, eight-hour or daily activity monitoring is prescribed. The condition for accurate results is the patient's immobility during the examination.

At the moment, the electroencephalogram is the most accessible and frequently used research method in neurology and neurosurgery, which shows changes in the state of cellular activity of the brain.

The EEG result is presented in the form of a recording on a computer or on paper. Curves are recorded on paper and analyzed by a doctor. The rhythm of the waves and amplitude are assessed, the elements are identified and how they are distributed in space is recorded. Next, all the data obtained is combined and displayed in a conclusion, then it is pasted into the patient’s chart.

What does an EEG diagnose?

Thanks to the electroencephalogram, the dynamics of the disease and the reaction to the influence of medications taken by the patient are monitored. EEG makes it possible to observe changes, which is a distinctive feature from basic diagnostic methods such as MRI and CT. This process is painless, does not take much time and does not entail negative reactions.

EEG is an accurate and harmless research method.

The electroencephalogram is displayed as a curve as a result of recording fluctuations in electrical activity. As a result, the entire process of brain activity is observed.

A 24-hour EEG is not included in the mandatory examinations. Doctors prefer not to resort to modern technologies while it is possible to get by with familiar treatment methods. However, if the diagnosis is difficult to make, then they resort to an electroencephalogram study.

Indications for the procedure

If there is any suspicion of a deviation in the functions and functioning of neuron cells, an electroencephalogram is performed. It is prescribed to patients upon diagnosis:

• Concussion or trauma to the skull;
• After operations affecting the performance of the nervous system;
• When diagnosing neoplasms of cysts and tumors;
• For epilepsy;
• With manifestations of a neurological nature;
• Delayed speech or mental development in a child;
• Disease;
• If the patient is unable to explain the sensations (in childhood);
• Sleep disturbances.

The main goals of diagnosing an electroencephalogram are:

1. Assessment of the depth and severity of pathologies;
2. Identification of the site;
3. Assessing how effective current treatment is and adjusting it if necessary;
4. Study of active processes of the nervous system and prevention of epileptic attacks and convulsive conditions;
5. An encephalogram is needed to determine the vital activity and performance of a patient who is under or in a coma.

The duration is from 30 to 40 minutes, unless the doctor has prescribed a daily EEG. The length of the examination depends on what disease needs to be diagnosed, but the examination is unlikely to take longer, even in serious cases.

Preparing for an EEG

To prepare for the procedure, stop taking anti-seizure medications three days before the examination. Do not use additional hair care products. Let down your long hair and remove any jewelry.

When preparing a child, he must be reassured and made clear that he will not be harmed or hurt.

EEG is not performed on people who have a cold or viral disease.

The examination is carried out while the child is sleeping, which makes it possible to accurately assess the baby’s condition and quickly detect pathological changes to prevent the development of serious consequences. To register the EEG, a special cap is put on the child’s head, and the doctor places electrodes under it. The scalp is pre-wetted with gel or water. Two inactive electrodes are applied to the ears, which are connected using clamps to the wires connected to the device. The current strength is small, which makes the examination a completely harmless procedure. Electroencephalogram is absolutely safe even for infants. A timely examination will detect the disease at an early stage. Indications for which an EEG of the child’s brain is performed:

• Injuries or bruises
• Monitoring the baby in the first year of life
• Migraine, fainting, dizziness
• Increased nervousness
• Insomnia

EEG diagnostics and conclusion

During the examination, the patient is in a room isolated from sound and light in a chair or on a couch. The doctor is in another room and communicates using a camera and microphone.

When using a good device and the patient being examined is immobile, an electroencephalogram reveals even minor changes in brain activity.

The final conclusion is made by a specialist, taking into account the symptoms that worry the patient.

Key aspects:

• Alpha rhythm. The norm is 8-14 Hz, the amplitude between the hemispheres is within 100 µV in a healthy person. A disturbance in the alpha rhythm indicates the presence of a tumor, cyst or heart attack. Instability and increased frequency indicate injury that may occur after a concussion. If the alpha rhythm is absent, then this indicates decreased mental activity;
• Beta Rhythm. More often it manifests itself in the frontal cerebral lobes in the two hemispheres with a symmetrical amplitude of 3-5 μV. Detects pathology with the following symptoms: asymmetry exceeds 50%, amplitude greater than 7 μV, sinusoidal beta rhythm, paroxysmal discharges;
• Theta and delta rhythm. Fixation occurs during sleep. The appearance of waves during wakefulness indicates existing dystrophic pathologies in the tissues;
• BEA (bioelectric activity). This aspect, in conclusion, is a holistic characteristic of brain rhythms. Synchronous activity without paroxysms is considered the norm. Changes are observed with depression.

Purpose

Video

A painless and fairly effective method of studying the brain is electroencephalography (EEG). It was first used back in 1928 by Hans Berger, but it is still used in the clinic. Patients are referred to it for certain indications in order to diagnose various brain pathologies. EEG has virtually no contraindications. Thanks to a carefully developed methodology and computer decoding of the data obtained, it helps the clinician to recognize the disease in time and prescribe effective treatment.

Indications and contraindications for EEG

Bioelectrical activity of the brain reflects the state of wakefulness, metabolism, hemo- and liquor dynamics. It has its own age-related characteristics, but in pathological processes it differs significantly from the norm, therefore, using an EEG, the presence of brain damage can be detected.

This research method is safe and is used to detect various brain diseases even in newborns. EEG is effective for diagnosing pathologies in patients who are unconscious or in a coma. With the help of modern devices and computer data processing, electroencephalography displays:

• functional state of the brain;
• presence of brain damage;
• localization of the pathological process;
• dynamics of the brain state;
• the nature of pathological processes.

These data help the clinician make differential diagnoses and prescribe the optimal therapeutic course. Subsequently, EEG is used to monitor how the treatment is progressing. Electroencephalography is most effective for diagnosing such pathologies:

• epilepsy;
• vascular lesions;
• inflammatory diseases.

If a pathology is suspected, the clinician uses an EEG to identify:

• is it diffuse or focal brain damage;
• side and localization of the pathological focus;
• Is this change superficial or deep?

In addition, EEG is used for monitoring the development of the disease and the effectiveness of treatment. During neurosurgical operations, a special method of recording brain biopotentials is used - electrocorticography. In this case, recording is carried out using electrodes immersed in the brain.

Electroencephalography is one of the safest and non-invasive methods for studying the functional state of the brain. It is used to register the biopotentials of the brain at different levels of consciousness in the patient. If there is no bioelectrical activity, this indicates brain death.

EEG is an effective diagnostic tool when it is not possible to check reflexes or question the patient. Its main advantages:

• harmlessness;
• non-invasive;
• painlessness.

There are no contraindications to the procedure. You cannot try to decipher the electroencephalogram on your own. This should only be done by a specialist. Even a neurologist and neurosurgeon need a detailed transcript. Incorrect interpretation of data will lead to treatment being ineffective.

If the patient determines that he has a more serious illness than he actually has, then nervous overstrain will significantly worsen his health condition.

The procedure must be performed by a neurophysiologist. Since too many external factors can affect the data obtained, a special methodology has been developed.

How is an EEG performed?

To avoid the influence of external stimuli, EEG is done in a light- and sound-proof room. Before the procedure you cannot:

• take a sedative;
• be hungry;
• be in a state of nervous excitement.

To record biopotentials, an ultrasensitive device is used - an electroencelograph. Electrodes are attached to the patient's head according to the generally accepted scheme. They can be:

• lamellar;
• cup;
• needle-shaped.

To begin, record background activity. At this time, the patient is in a comfortable chair in a reclining position, with his eyes closed. Then, to further determine the functional state of the brain, provocative tests are done:

1. Hyperventilation. The patient makes deep breathing movements 20 times per minute. This leads to alkalosis, a narrowing of the blood vessels in the brain.
2. Photostimulation. A test with a light stimulus is carried out using a strobe light. If there is no reaction, then the conduction of visual impulses is impaired. The presence of pathological waves on the EEG indicates increased excitability of cortical structures, and prolonged irritation with light provokes the occurrence of true convulsive discharges; a photoparoxysmal reaction, characteristic of epilepsy, may occur.
3. Test with sound stimulus. It, like the light test, is necessary for differentiating true, hysterical or feigning visual and auditory disorders.

Carrying out the procedure for children under 3 years of age is difficult due to their restless state and failure to follow instructions. That’s why their electroencephalography technique has its own characteristics:

1. Infants are examined on a changing table. If the child is awake, he should be in the arms of an adult with his head raised or sitting (after 6 months).
2. To identify an alpha-like rhythm, it is necessary to attract the child’s attention with the help of a toy. He must fix his gaze on her.
3. As a last resort, an EEG is done when the baby comes out of medicated sleep.
4. The hyperventilation test is performed on children over 1 year of age in a playful way; they are asked to blow on hot tea or asked to inflate a balloon.

The electroencephalographer analyzes the received data and transmits the transcript to the clinician. Before making a final diagnosis, a neurologist or neurosurgeon looks not only at the EEG results, but also prescribes other tests (, cerebrospinal fluid), and evaluates reflexes. If a tumor is suspected, a CT scan is recommended. Imaging diagnostic methods more accurately determine the location of organic brain damage.

Conclusion

Indications for electroencephalography are suspicion of epilepsy, tumor, diffuse brain damage. It reflects the functional state of the central nervous system, thereby helping the neurologist or neurosurgeon in making an accurate diagnosis and monitoring effectiveness. An electroencephalographer conducts the examination and interprets the data obtained, taking into account the age characteristics of the patient.

Medical educational film “Electroencephalography”:

Functional diagnostics doctor Yu. Krupnova talks about EEG:

Many patients have encountered such a diagnostic method as an electroencephalogram of the brain. The definition and essence of this type of research are extremely important for effective treatment and accurate determination of the patient's condition. Therefore, it makes sense to consider EEG in more detail.

What is an electroencephalogram of the brain

This terminology is used to describe one of the methods for diagnosing the state of the brain, which is based on the process of recording its electrical activity.

Based on what the electroencephalogram of the brain shows, doctors can identify various pathologies in the blood vessels, the development of inflammatory diseases, as well as signs of tumors and epilepsy. It is worth noting the important fact that EEG is the only outpatient research method that makes it possible to diagnose an unconscious person. Moreover, this technique does not pose a danger to patients of any age category, including children.

Using what electroencephalography of the brain shows, doctors can record the effects of various drugs on patients, assess the dynamics of the course of the disease, and also make adjustments to treatment methods. Continuing to consider the features of EEG, it should be noted that this type of study is used to track all changes in the brain - from reversible to structural. This is one of the main differences between this technique and other methods of examining a patient.

What does an EEG look like?

As for the visual component, the electroencephalogram has the form of a simple curve, which is formed in the process of recording fluctuations in the electrical activity of the brain. It is this curve that allows the doctor to get a clear picture of how brain activity manifests itself. To determine the nature of a particular disease and its degree, a special card is used.

What a brain electroencephalogram shows is extremely important information when assessing and treating problems related to the central nervous system. We are talking about the property of rhythm, with the help of which it becomes possible to accurately display the activity of all structures located in the brain. Another indicator recorded using EEG is the way the brain uses its own reserves.

Indications for EEG

It is important not only to know the essence of the definition of “electroencephalogram of the brain”, what this study shows and what characteristics it has, but also to understand for whom this type of diagnosis is relevant.

Initially, it is necessary to clarify the fact that no one will do an EEG without a referral. And although this procedure is not capable of causing harm to patients in any condition, doctors, before using this diagnostic resource, collect a picture of the disease of a particular person. And only if classical methods do not allow one to accurately determine the essence of the disease, an EEG is prescribed.

However, there are situations in which an electroencephalogram is required:

If there is a suspicion of a tumor;

When the patient is not able to objectively assess his own feelings or is too young for this (children);

If the patient has had a disturbed sleep pattern for a long time or suffered from insomnia;

In case of psychopathy, nervous breakdowns and psychoses;

If a brain lesion was recorded that developed from;

When the patient has vascular diseases;

Development of necrosis during surgery;

If the patient is in serious condition resulting from poisoning or injury;

With the patient.

With such difficulties, an electroencephalogram of the brain is extremely important, which shows the relevance of this technique in working with patients of various groups.

Preparing for the study

There are several simple rules that need to be followed before the test is carried out. What this study shows largely depends not only on the patient’s condition, but also on other factors. So, for a more accurate diagnosis, you need to stop using anticonvulsants a few days before the procedure.

It is important to wash your hair before the examination. In this case, you cannot use mousses, creams, styling varnishes, foams and gels. You should also pay attention to your hairstyle: if you have dreadlocks or braids, you need to undo them, after which you will have to remove all metal elements (piercings, jewelry).

It is important to know that this diagnostic procedure is not relevant for those patients who at the time of the study are suffering from viral or colds.

Algorithm

Understanding what the electroencephalogram of the brain shows, it makes sense to pay attention to the procedure itself.

Brain research begins with an EEG procedure that is commonly called routine. At this stage, the brain is analyzed. For 10-15 minutes, the biological potentials of the brain are recorded using a graphic recording and standard functional tests are performed.

If the use of a routine EEG does not give the desired results, doctors may prescribe an electroencephalogram with sleep deprivation. We are talking about the following procedure: the patient is woken up several hours earlier than usual or deprived of sleep all night, after which they begin to study the electronic impulses of the brain.

Within the framework of the topic “EEG of the brain - price, preparation and description,” it is worth noting that if paroxysm is suspected, a long procedure may be prescribed, during which sleep registration is performed. This approach makes it possible to obtain more accurate data.

If we talk about the most complete EEG, then this is a study that is carried out during sleep, before it and immediately after waking up. During these periods, diagnosing the state of the brain is much easier. As for the cost of the procedure, it may vary depending on the type of medical institution, as well as the region. But on average, the price of an EEG ranges from 1,500 to 2,000 rubles.

Features of the procedure

There are a number of nuances that may seem unusual to those who have never attended an EEG. An electroencephalogram of the brain is carried out using a specific device that looks like a cap, which is placed on the patient’s head. This device is necessary for high-quality installation of electrodes. The number of the latter directly depends on the fact how old the patient is. For example, if a child’s brain activity is being studied, 12 electrodes are used. In the case of adults who are already of age, this number increases to 21.

The process does not end there: the electrodes are filled with a substance that allows the rapid transmission of electrical impulses. Next, the device, fixed on the patient’s head, is connected via wiring to an electroencephalograph, which initially amplifies the received signal and then transmits it to a computer for subsequent processing.

Already in the computer, the signal takes on a wave-like form, allowing doctors to assess the state of the brain in general and the activity of cells in particular.

The need to use EEG

It is difficult to overestimate the relevance of what the electroencephalogram of the brain shows. This information allows you to identify fairly complex diseases and abnormalities that may not have visible symptoms. It is worth noting that at the moment more modern diagnostic techniques are available to patients. We are talking about magnetic resonance and computed tomography.

Nevertheless, EEG is still actively used in Russian clinics, allowing doctors to make fairly accurate diagnoses. The use of this technique is especially important when working with patients suffering from epilepsy. This is explained by the fact that EEG makes it possible to record important details and features of the patient’s condition at any time.

Sleep monitoring

This procedure, during which EEG is used, is of great importance in diagnosing diseases, as well as in assessing the process of their occurrence. As mentioned above, an electroencephalogram can be performed at different times, and the sleep period is the most optimal.

Leading epileptologists confirm that it is this type of EEG that makes it possible to make more accurate diagnoses, as well as to better adjust and monitor therapy for epilepsy. Often, mental development disorders in children that are not detected during routine examination are detected during EEG sleep monitoring of the brain, which shows the higher efficiency of this approach to diagnosis.

How to prepare your baby for sleep monitoring

In order for the diagnostic procedure to be extremely effective, you need to wake up the child 2 hours earlier than his usual awakening. After this, during the day you need to make sure that the baby does not fall asleep. To do this, you will have to spend time with him quite actively.

Preparation for the examination can begin after 18-00. Its essence comes down to limiting the consumption of sweets and liquids, as well as salty and spicy foods. At the same time, you should avoid any factors that could lead to overstimulation of the child.

in children, how it goes and why

For an extremely accurate diagnosis of the child’s condition, the sleep monitoring technique described above is used. At the same time, there are a number of indications for carrying out this diagnostic procedure in the case of children:

When there is suspicion of ischemic damage to the central nervous system;

To assess the severity of the disease;

For epileptic seizures and pseudo-seizures;

To assess the correct development and formation of bioelectrical activity in children at the earliest stage of their life (infants);

In the case when there is a need to predict the development of brain damage and assess its dynamics.

The procedure itself is carried out between 8 and 9 pm at home. This allows you to record the activity of the child's brain before bed and after falling asleep. Otherwise, the algorithm of actions is the same as when working with adults.

It is worth noting that even for infants such a research method as EEG of the brain is absolutely safe. There will always be important diagnostics, regardless of the technique, but this type of assessment of the state of the brain will remain one of the most relevant for a long time.

Conclusion

The conclusion regarding the use of EEG is obvious - this technique is necessary for the efficient operation of clinics and accurate diagnosis of patients of various groups. However, this procedure remains one of the most accessible.

] are taken into account when diagnosing disorders and pathologies of the central nervous system. This is a study of brain functionality based on passive recording of frequency signals. What is EEG decoding, what parameters are used to perform it? What do the phrases and conclusions written in the conclusion mean? We explain it simply and in detail in this article.

Diagnosis of brain functions using EEG is based on recording signals and comparing them with indicators of bioelectrical activity of the brain (BEA) of a conditionally healthy person. Of course, there is no single sample or standard for comparison. Neurophysiologists know the normal parameters of BEA for people of different ages, and there are observations in certain pathologies. Based on these data, it is possible to decipher the encephalogram, taking into account the developmental characteristics and health status of the patient.

The norm in the EEG results - what is the picture in a healthy person

The normal functioning of the brain is based on a frequency pattern of a combination of several rhythms. They have a certain localization, frequency and amplitude (maximum value), and can overlap and be suppressed by each other. For an examination, it is enough to record four types of signals, but sometimes there is a need to monitor all indicators.

Rhythms of bioelectrical activity of the brain during wakefulness

Let us briefly describe these frequency characteristics for a person in a state of normal rest, but not in sleep.

1. Alpha rhythm is inherent in most healthy people. It is defined as a signal with a frequency of 8 to 14 Hz when the subject is in a dark room, at rest, with his eyes closed. Localized in the back of the head and closer to the crown, evenly distributed (symmetrical) across the hemispheres of the brain. When visual signals appear and thinking (problem solving) may partially fade or be blocked.

2. The beta rhythm of brain activity manifests itself at a frequency of 13 to 30 Hz with obvious activity, attention and anxiety, and the receipt of external information. This is the rhythm of attention and activity, it is found in the frontal region of the brain. The amplitude is significantly inferior to the alpha rhythm. In a state of rest and absence of external signals, it calms down.

3. The gamma rhythm on the encephalogram is recorded with a significant frequency range from 30 to 120-180 Hz, which is fully explained by its purpose - this frequency occurs when solving mental problems, if necessary, to concentrate, to achieve concentration. The amplitude of gamma rhythm oscillations is very small, and when it reaches a value of 15 μV, doctors talk about pathology, a sharp loss of intellectual potential, and a disorder of mental function.

4. The kappa rhythm is interesting because it is actually a blocking signal for the alpha rhythm, when a person needs to move from a state of rest to mental work. A signal with a frequency of 8 - 12 Hz occurs in the temporal part. Its shape and frequency are such that when applied to the alpha rhythm, the latter’s oscillations fade away.

5. The lambda rhythm or “visually active” signal of medium frequency and a very narrow range occurs in the back of the head when a person activates the connection between vision and mental activity and attention - it is maintained when solving the task of searching for an object or image and fades away when fixing the gaze. During the search period, it partially extinguishes the alpha rhythm in the visual zone.

6. The mu rhythm signal is very similar to the alpha rhythm - it arises in the back of the head, has the same frequency range and actually maintains the alpha rhythm at rest, serving as a kind of frequency stabilizer that prevents the brain from losing balance too quickly with minor stimuli. The mu rhythm disappears as soon as any type of activity begins.

Rhythms of brain signals during sleep

In a state of sleep and transition to sleep, during blackout and coma, other BEA rhythms operate. Their appearance during wakefulness is alarming, as it is considered a sign of pathological processes, including cancer and epileptic nature.

1. The delta rhythm occurs during deep sleep and in coma. In children, it can manifest itself both at rest and during activity, and registration of delta oscillations while an adult is awake may mean that the encephalograph has “caught” the border of the oncological process.

2. The theta rhythm plays the role of a filtering agent, which is provoked by the hippocampus during sleep to process previously received information. Self-learning and filtering of data that the brain must process and remember depend on its stability. Its appearance outside sleep can be a sign of latent epilepsy, pre-epileptic aura.

3. The sigma rhythm is fixed in the initial stage of sleep, during the transition between phases of sleep, when the theta rhythm changes to the delta rhythm. It is considered an important diagnostic indicator in identifying problems with sleep and attention.

Based on the recorded signals, the overall BEA indicator of the brain is derived. Next, specialists begin to decipher the EEG according to the main signs and criteria. Attention is paid to frequency and amplitude indicators, pulse modulation, smoothness of graphs, localization and symmetry of their distribution. How to understand where is the norm and where is the violation?

Before evaluating the decryption results, you need to understand. This study is functional, which means that its results can be used to judge the functioning of the brain. A full diagnosis is not made on the basis of an EEG, but it is possible to assume the presence of pathologies, confirm or exclude some disorders. This can be explained something like this: if a person has signs of epilepsy, hidden seizures, then the EEG decoding of the theta rhythm will show the frequency value even when awake. But you will have to order a series of examinations to understand what is causing the attacks - a tumor, a scar from a stroke, inflammation in a separate part of the cerebral cortex.

What is interpretation of EEG results?

Is it possible to decipher EEG results yourself? This is impossible without knowledge of neurophysiology. There are many specific factors that need to be taken into account. If such a decoding is made without taking into account the individual characteristics of the patient, the result will be at least vague. In the worst case, you will find signs of terrible diseases, get neurosis and depression, but in reality it turns out that the result is not terrible.

What do doctors look at when deciphering encephalogram data?

After receiving the result in the form of recording signals on paper tape, the neurophysiologist studies them according to the main criteria:

• frequency and amplitude of oscillations - deviations from the norm may be within acceptable values ​​or deviate from them;

• the shape of the overall signal graph - it should be correct, smooth, without jumps and dips;

• distribution of rhythms across hemispheres and zones - knowing where the reading electrode is located, you can determine the localization of a specific rhythm;

• symmetry of signals - in most cases, uniform distribution between the hemispheres is considered the norm;

• dependence of the rhythm on the patient’s condition - in sleep, at rest, when stimulated by light, sound, activity;

• the presence of paroxysms - repeated short interruptions in frequency and rhythm.

Violations of the BEA of the brain in the recording are identified and recorded initially in order to subsequently determine their connection with pathologies.

Examples of violations of BEA and rhythms on the encephalogram

For alpha brain activity, pathology is considered to be a constant presence in the frontal lobes, an asymmetry between the hemispheres exceeding 35%, a non-sinusoidal graph, scatter and instability of frequency, increased and decreased amplitude. Based on the combination of signs of alpha rhythm disturbance, one can assume cancer and circulatory disorders in the brain.

Deviations in the amplitude of beta brain activity towards consistently high levels indicate the likelihood of a concussion. If spindle-shaped signals appear, encephalitis may be suspected. In children, a high amplitude of oscillations in the center and front of the brain can serve as a signal of delayed mental and mental development.

High amplitude sleep rhythms (delta and theta) indicate functional disorders. If a signal with such deviations is widely distributed throughout the brain and is recorded in all parts, then there is a high probability of severe disorders in the central nervous system.

Important! - indicators of normality and abnormalities on the EEG depend on age! Features of brain development must be taken into account when deciphering!

Decoding the encephalogram for some diseases

Specific diseases can give a well-described picture on the EEG. Thus, when taking data during an epileptic attack, you can quite accurately determine the place of its origin by the peaks on the encephalogram. During an attack, pointed waves appear especially clearly. Burst-like increases in signal amplitude may be present.

With traumatic brain injuries with minor consequences, EEG rhythms will be unstable and asymmetrical. If the pattern of rhythm disturbances increases within a week after the injury, alpha oscillations slow down, then a conclusion is drawn about the serious consequences of the injury.