Good EEG results. In what cases can an encephalogram of the brain be prescribed: indications and description of the diagnostic method. Deciphering the indicators of the electroencephalogram

Brain electroencephalography is a method in electrophysiology that registers the bioelectrical activity of brain neurons by removing them from the surface of the head.

The brain has bioelectrical activity. Each nerve cell of the central nervous system is able to create an electrical impulse and transmit it to neighboring cells using axons and dendrites. There are approximately 14 billion neurons in the cerebral cortex, each of which creates its own electrical impulse. Separately, each impulse does not represent anything, however, every second the total electrical activity of 14 billion cells creates an electromagnetic field around the brain, which is recorded by the electrocypogram of the brain.

EEG monitoring reveals functional and organic pathologies of the brain, such as epilepsy or sleep disorders. Electroencephalography is performed using a device - an electroencephalograph. Is it harmful to do the procedure with an electroencephalograph: the study is harmless, since the device does not send a single signal to the brain, but only captures outgoing biopotentials.

An electroencephalogram of the brain is a graphical representation of the electrical activity of the central nervous system. It depicts waves and rhythms. Their qualitative and quantitative indicators are analyzed and a diagnosis is issued. The analysis is based on rhythms - electrical vibrations of the brain.

Computed electroencephalography (CEEG) is a digital method for recording brain wave activity. Outdated electroencephalographs display a graphical result on a long tape. CEEG displays the result on the computer screen.

There are such rhythms of the brain, which are recorded on the electroencephalogram:

Alpha rhythm.

Its amplitude increases in a state of calm wakefulness, for example, when resting or in a dark room. Alpha activity on the EEG decreases when the subject moves to active work that requires a high concentration of attention. In people who have been blind all their lives, there is a lack of alpha rhythm on the EEG.

Beta rhythm.

It is characteristic of active wakefulness with a high concentration of attention. The most clearly beta activity on the EEG is expressed in the projection of the frontal cortex. Also, on the electroencephalogram, the beta rhythm appears with a sharp appearance of an emotionally significant new stimulus, for example, the appearance of a loved one after a few months of separation. The activity of the beta rhythm also increases with emotional stress and work that requires a high concentration of attention.

Gamma rhythm.

This is a set of low-amplitude waves. The gamma rhythm is a continuation of the beta waves. Thus, gamma activity is recorded at a high psycho-emotional load. The founder of the Soviet school of neuroscience, Sokolov, believes that the gamma rhythm is a reflection of the activity of human consciousness.

Delta rhythm.

These are high amplitude waves. It is recorded in the phase of deep natural and drug-induced sleep. Also, delta waves are fixed in a state of coma.

Theta rhythm.

These waves are generated in the hippocampus. Theta waves appear on the EEG in two states: the phase of rapid eye movement and high concentration of attention. Harvard professor Schacter claims that theta waves appear during altered states of consciousness, for example, in a state of deep meditation or trance.

Kappa rhythm.

Registered in the projection of the temporal cortex of the brain. It appears in the case of suppression of alpha waves and in a state of high mental activity of the subject. However, some researchers associate the kappa rhythm with normal eye movement and regard it as an artifact or side effect.

Mu-rhythm.

Appears in a state of physical, mental and emotional rest. It is registered in the projection of the motor lobes of the frontal cortex of the brain. Mu-waves disappear in the case of the imaging process or in a state of physical activity.

EEG norm in adults:

Alpha rhythm: frequency - 8-13 Hz, amplitude - 5-100 μV.
Beta rhythm: frequency - 14-40 Hz, amplitude - up to 20 μV.
Gamma rhythm: frequency - 30 or more, amplitude - no more than 15 μV.
Delta rhythm: frequency - 1-4 Hz, amplitude - 100-200 μV.
Theta rhythm: frequency - 4-8 Hz, amplitude - 20-100 μV.
Kappa rhythm: frequency - 8-13 Hz, amplitude - 5-40 μV.
Mu-rhythm: frequency - 8-13 Hz, amplitude - an average of 50 μV.

The conclusion of the EEG of a healthy person consists of just such indicators.

Types of EEG

There are the following types of electroencephalography:

Night EEG of the brain with video support. During the study, electromagnetic waves of the brain are recorded, and video and audio research allows you to evaluate the behavioral and motor activity of the subject during sleep. Daily monitoring of the EEG of the brain is used when it is necessary to confirm the diagnosis of epilepsy of complex origin or to establish the causes of convulsive seizures.
Brain mapping. This variety allows you to map the cerebral cortex and mark pathological emerging foci on it.
Electroencephalography with biofeedback. It is used to train the control of brain activity. Thus, the subject, when applying sound or light stimuli, sees his encephalogram and tries to mentally change its indicators. There is little information about this method and it is difficult to evaluate its effectiveness. It is claimed to be used for patients who have resistance to antiepileptic drugs.

Indications for appointment

Electrophysiological research methods, including an electroencephalogram, are indicated in such cases:

A seizure was diagnosed for the first time. Convulsive attacks. Suspicion of epilepsy. In this case, the EEG reveals the cause of the disease.
Evaluation of the effectiveness of drug therapy in well-controlled and drug-resistant epilepsy.
Postponed traumatic brain injury.
Suspicion of a neoplasm in the cranial cavity.
Sleep disorders.
Pathological functional states, neurotic disorders, such as depression or neurasthenia.
Evaluation of brain performance after stroke.
Evaluation of involutional changes in elderly patients.

Contraindications

EEG of the brain is an absolutely safe non-invasive method. It registers electrical changes in the brain by removing potentials with electrodes that do not adversely affect the body. Therefore, an electroencephalogram has no contraindications and can be performed on any patient who has a brain.

How to prepare for the procedure

How to prepare:

For 3 days, the patient must abandon anticonvulsant therapy and other drugs that affect the functioning of the central nervous system (tranquilizers, anxiolytics, antidepressants, psychostimulants, hypnotics). These drugs affect the inhibition or excitation of the cerebral cortex, due to which the EEG will show unreliable results.
For 2 days you need to make a small diet. Drinks containing caffeine or other stimulants of the nervous system should be avoided. It is not recommended to drink coffee, strong tea, Coca-Cola. You should also limit dark chocolate.
Preparation for the study includes shampooing: the recording sensors are placed on the scalp, so clean hair will provide the best contact.
Before the study, it is not recommended to apply hairspray, gel and other cosmetics that change the density and consistency of the hair.
Do not smoke two hours before the study: nicotine stimulates the central nervous system and can distort the results.

Preparation for the EEG of the brain will show a good and reliable result that does not require re-examination.

Description of the process on the example of EEG video monitoring. The study is day and night. The first usually starts from 9:00 to 14:00. The night option usually starts at 21:00 and ends at 9:00. Lasts all night.

Before starting the diagnosis, the subject is put on an electrode cap, and a gel is applied under the sensors that improves conductivity. The headdress is fixed on the head with fasteners and fasteners. The cap is worn on the person's head during the entire procedure. The EEG cap for children under 3 years of age is additionally strengthened due to the small size of the head.

All research is carried out in an equipped laboratory, where there is a restroom, a refrigerator, a kettle and water. You will talk to a doctor who needs to find out your current state of health and readiness for the procedure. First, part of the study is carried out during active wakefulness: the patient reads a book, watches TV, listens to music. The second period begins during sleep: the bioelectrical activity of the brain during the slow and fast phases of sleep is assessed, behavioral acts during dreams, the number of awakenings and extraneous sounds, such as snoring or talking during sleep, are assessed. The third part begins after waking up and captures brain activity after sleep.

In the course, photostimulation with EEG can be used. This procedure is necessary to assess the difference between brain activity during deprivation of external stimuli and during the application of light stimuli. What is noted on the electroencephalogram during photostimulation:

decrease in the amplitude of rhythms;
photomyoclonus - polyspikes appear on the EEG, which are accompanied by twitching of the muscles of the face or muscles of the limbs;

Photostimulation can provoke epileptiform responses or an epileptic seizure. This method can be used to diagnose latent epilepsy.

An EEG hyperventilation test is also used to diagnose latent epilepsy. The subject is asked to breathe deeply and regularly for 4 minutes. This method of provocation makes it possible to detect epileptiform activity on the electroencephalogram or even provoke a generalized convulsive seizure of an epileptic nature.

Daytime electroencephalography is done in a similar way. It is carried out in a state of active or passive wakefulness. The time is from one to two hours.

How to pass an EEG so that nothing is found? The electrical activity of the brain reveals the slightest changes in the wave activity of the brain. Therefore, if there is a pathology, for example, epilepsy or circulatory disorders, the specialist will identify it. The norm and pathology on the EEG are always visible, despite all attempts to hide unpleasant results.

When it is impossible to transport the patient, an EEG of the brain is performed at home.

For children

Children do an EEG using a similar algorithm. The child is put on a mesh cap with fixed electrodes and put on the head, before having treated the surface of the head with a conductive gel.

How to prepare: the procedure does not cause any discomfort or pain. However, children are still scared because they are in the doctor's office or in the laboratory, which already initially forms the installation that it will be unpleasant. so, before the procedure, the child should be explained what exactly will happen to him, and that the study is not painful.

A hyperactive child may be given a sedative or sleeping pill before the test. This is necessary so that during the study, unnecessary movements of the head or neck do not remove the contact between the sensors and the head. The research is carried out in a dream for an infant.

Result and interpretation

Conducting an EEG of the brain gives a graphical result of the bioelectrical activity of the central nervous system. It can be a tape record or an image on a computer. Deciphering an electroencephalogram is an analysis of the indicators of waves and rhythms. So, the obtained indicators are compared with the normal frequency and amplitude.

There are the following types of EEG disorders

Normal performance, or organized type. It is characterized by a main component (alpha waves) that have regular and regular frequencies. The waves are smooth. Beta rhythms are predominantly medium or high frequency with a small amplitude. There are few slow waves or they are almost not expressed.

The first type is divided into two subtypes:
- version of the ideal norm; here the waves are not changed in principle;
- subtle violations that do not affect the functioning of the brain and the mental state of a person.
hypersynchronous type. It is characterized by a high wave index and increased synchronization. However, the waves retain their structure.
Disruption of synchronization (flat EEG type, or desynchronous EEG type). The severity of alpha activity decreases with an increase in the activity of beta waves. All other rhythms are within normal limits.
EEG of a disorganized type with pronounced alpha waves. It is characterized by high activity of the alpha rhythm, but this activity is irregular. The disorganized type of EEG with alpha rhythm does not have sufficient activity and can be recorded in all parts of the brain. High activity of beta, theta and delta waves is also recorded.
EEG disorganization with a predominance of delta and theta rhythms. It is characterized by low activity of alpha waves and high activity of slow rhythms.

Type one: Electroencephalogram showing normal brain activity. The second type reflects a weak activation of the cerebral cortex, more often indicates a violation of the brain stem with a violation of the activating function of the reticular formation. The third type reflects increased activation of the cerebral cortex. The fourth type of EEG shows dysfunction in the work of the regulatory systems of the central nervous system. The fifth type reflects organic changes in the brain.

The first three types in adults occur either normally or with functional changes, such as neurotic disorders or schizophrenia. The last two types indicate gradual organic changes or the onset of brain degeneration.

Changes in the electroencephalogram are often nonspecific, but some pathognomonic nuances make it possible to suspect a specific disease. For example, irritative EEG changes are typical non-specific indicators that can manifest themselves in epilepsy or vascular diseases. With a tumor, for example, the activity of alpha and beta waves decreases, although these are considered irritative changes. Irritative changes have the following indicators: alpha waves become aggravated, activity of beta waves increases.

On the electroencephalogram, focal changes can be recorded. Such indicators indicate focal dysfunction of nerve cells. However, the nonspecificity of these changes does not allow us to draw a delimiting line between cerebral infarction or suppuration, since in any case the EEG will show the same result. However, it is known for sure: moderate diffuse changes indicate an organic pathology, not a functional one.

EEG is of the greatest value for diagnosing epilepsy. Between individual seizures, epileptiform phenomena are recorded on the tape. In addition to overt epilepsy, such phenomena are recorded in people who have not yet been diagnosed with epilepsy. Epileptiform patterns consist of spikes, sharp rhythms, and slow waves.

However, some individual characteristics brain can produce spikes even when the person is not sick with epilepsy. It happens in 2%. However, in people suffering from epilepsy, epileptiform adhesions are recorded in 90% of all diagnostic cases.

Also, with the help of electroencephalography, it is possible to establish the spread of convulsive brain activity. So, the EEG allows you to establish: pathological activity extends to the entire cerebral cortex or only to some of its parts. This is important for the differential diagnosis of forms of epilepsy and the choice of treatment tactics.

Generalized seizures (convulsions throughout the body) are associated with bilateral pathological activity and polyspikes. So, the following relationship is established:

Partial epileptic seizures correlate with spikes in the anterior temporal gyrus.
Loss of sensation in or before epilepsy is associated with abnormal activity near the Roland sulcus.
Visual hallucinations or decreased visual fidelity during or before a seizure is associated with spikes in the projection of the occipital cortex.

Some syndromes on the EEG:

Hypsarrhythmia. The syndrome is manifested by a violation of the rhythm of the waves, the appearance of sharp waves and polyspikes. Manifested in infantile spasms and West syndrome. Most often, it confirms a diffuse violation of the regulatory functions of the brain.
The manifestation of polyspikes with a frequency of 3 Hz indicates a small epileptic seizure, for example, such waves appear in a state of absence. This pathology is characterized by a sudden blackout of consciousness for a few seconds with the preservation of muscle tone and in the absence of a reaction to any external stimuli.
The group of polyspike waves indicates a classic generalized epileptic seizure with tonic and clonic convulsions.
Low-frequency spike waves (1-5 Hz) in children under 6 years of age reflect diffuse changes in the brain. In the future, such children are prone to impaired psychomotor development.
Spikes in the projection of the temporal gyri. They may be associated with benign epilepsy in children.
Dominant slow-wave activity, in particular delta rhythms, indicate an organic brain lesion as the cause of convulsive seizures.

According to electroencephalography, one can judge the state of consciousness in patients. Thus, there is a large variety of specific signs on the tape, which can be used to suggest a qualitative or quantitative impairment of consciousness. However, nonspecific changes often appear here, as, for example, with encephalopathy of toxic origin. In most cases, pathological activity on the electroencephalogram reflects the organic nature of the disorder, rather than functional or psychogenic.

By what signs is the disturbance of consciousness determined on the EEG against the background of metabolic disorders:

In a state of coma or stupor, high activity of beta waves indicates intoxication with drugs.
Three-phase wide waves in the projection of the frontal lobes indicates hepatic encephalopathy.
A decrease in the activity of all waves indicates a decrease in the functionality of the thyroid gland and hypothyroidism in general.
In a state of coma on the background diabetes The EEG shows wave activity in an adult, I look for epileptiform phenomena.
In a state of lack of oxygen and nutrients (ischemia and hypoxia), the EEG produces slow waves.

The following parameters on the EEG indicate a deep coma or possible death:

Alpha coma. Alpha waves are characterized by paradoxical activity, this is especially clearly recorded in the projection of the frontal lobes of the brain.
A strong decrease or complete absence of brain activity is indicated by spontaneous neural bursts, which alternate with rare high voltage waves.
"Electrical silence of the brain" is characterized by generalized polyspikes and island wave rhythms.

Brain diseases against the background of infection are manifested by nonspecific slow waves:

The herpes simplex virus or encephalitis is characterized by slow rhythms in the projection of the temporal and frontal cortex of the brain.
Generalized encephalitis is characterized by alternating slow and sharp waves.
Creutzfeldt-Jakob disease manifests itself on the EEG with three- and two-phase sharp waves.

The EEG is used in the diagnosis of brain death. So, with the death of the cerebral cortex, the activity of electrical potentials decreases as much as possible. However, a complete stop of electrical activity is not always final. So, the blunting of biopotentials can be temporary and reversible, as, for example, with a drug overdose, respiratory arrest

In the vegetative state of the central nervous system, isoelectric activity is noted on the EEG, which indicates the complete death of the cerebral cortex.

For children

How often can be done: the number of procedures is not limited, since the study is harmless.

EEG in children has features. The electroencephalogram shows in children up to a year (a full-term and painless child) periodic low-amplitude and generalized slow waves, mainly a delta rhythm. This activity has no symmetry. In the projection of the frontal lobes and parietal cortex, the amplitude of the waves increases. Slow-wave activity on the EEG in a child of this age is the norm, since the regulatory systems of the brain have not yet been formed.

EEG norms in children aged from one month to three: the amplitude of electrical waves increases to 50-55 μV. There is a gradual establishment of the rhythm of the waves. EEG results in three-month-old children: a mu-rhythm with an amplitude of 30-50 μV is recorded in the frontal lobes. The asymmetry of waves in the left and right hemispheres is also fixed. By 4 months of life, the rhythmic activity of electrical impulses is recorded in the projection of the frontal and occipital cortex.

Deciphering the EEG in children of one year of age. The electroencephalogram shows fluctuations in the alpha rhythm, which alternate with slow delta waves. Alpha waves are characterized by instability and lack of a clear rhythm. In 40% of the entire electroencephalogram, theta rhythm and delta rhythm dominate (50%).

Deciphering indicators in children of two years. The activity of alpha waves is recorded in all projections of the cerebral cortex as a sign of gradual activation of the activity of the central nervous system. Beta rhythm activity is also noted.

EEG in children 3-4 years old. Theta rhythm dominates on the electroencephalogram, slow delta waves predominate in the projection of the occipital cortex. Alpha rhythms are also present, but they are hardly noticeable against the background of slow waves. With hyperventilation (active forced breathing), sharpening of the waves is noted.

At the age of 5-6 years, the waves stabilize and become rhythmic. Alpha waves already resemble alpha activity in adults. Slow waves in their regularity no longer overlap alpha waves.

The EEG in children 7-9 years old registers the activity of alpha rhythms, but to a greater extent these waves are recorded in the crown projection. Slow waves recede into the background: their activity is no more than 35%. Alpha waves make up approximately 40% of the entire EEG, and theta waves - no more than 25%. Beta activity is recorded in the frontal and temporal cortex.

Electroencephalogram in children 10-12 years old. Their alpha waves are almost ripe: they are organized and rhythmic, dominating throughout the entire graphic tape. Alpha activity accounts for approximately 60% of the entire EEG. These waves show the greatest voltage in the area of the frontal, temporal and parietal lobes.

EEG in 13-16 year old children. The formation of alpha waves is completed. The bioelectrical activity of the brain in healthy children acquired the features of the activity of the brain of a healthy adult. Alpha activity dominates in all parts of the brain.

Indications for the procedure in children are the same as in adults. For children, EEG is prescribed mainly for the diagnosis of epilepsy and the establishment of the nature of seizures (epileptic or non-epileptic).

Convulsions of a non-epileptic nature are manifested by the following indicators on the EEG:

Flashes of delta and theta waves are synchronous in the left and right hemispheres, they are generalized and are most expressed in the parietal and frontal lobes.
Theta waves are synchronous on both sides and are characterized by low amplitude.
The EEG shows arcuate spikes.

Epileptic activity in children:

All waves are sharpened, they are synchronous on both sides and generalized. Often occur suddenly. May occur in response to eye opening.
Slow waves are taken in the projection of the frontal and occipital lobes. They are registered in wakefulness and disappear if the child closes his eyes.

Violation of the brain activity leads to the appearance of neurological problems in the child. To identify the cause of unpleasant symptoms, the pediatrician prescribes instrumental diagnostic methods. The most informative is the EEG. The procedure is absolutely painless and safe even for newborns.

What is an EEG

Neurons are the structural unit of the brain. Their task is to generate and transmit electrical impulses to the rest of the cells of the body. The work of neurons forms the bioelectrical activity of the brain. EEG (electroencephalogram) is a diagnostic method that displays any functional changes in the functioning of the central nervous system and brain structures.

The development of the EEG began in the late 1930s. The method was constantly improved and became more widespread in the 80s. Today, EEG is actively used in psychiatry and neurology to diagnose brain lesions.

Electrodes (sensitivity sensors) are placed on the patient's head. They capture minimal biological currents, bursts of brain activity and transmit information to an electroencephalograph. The device amplifies the potential of electrical impulses, processes the collected data and fixes them on paper in the form of a curved line.

What does an encephalogram show?

An EEG of the head in a child is carried out according to a standard protocol with monitoring of brain activity during activity, sleep, or when exposed to stimuli. An electroencephalogram answers the following questions:

whether there are disturbances in the work of the brain, their degree of severity;
whether there is a change in the mode of sleep and wakefulness;
in what proportion are areas of increased activity;
whether the chosen treatment regimen is effective;
whether the dosage of drugs is calculated correctly.

Why do an EEG for children

The study is carried out to assess the state of health after loss of consciousness, craniocerebral injuries (concussion, brain contusion). The doctor prescribes an encephalogram if there are such indications or symptoms:

attention disorder;
frequent headaches;
convulsions or seizures;
suspected neoplasm or hemorrhage in the brain;
irascibility and irritability;
a sharp increase or decrease in blood pressure;
sleep disorders.

Indications for EEG monitoring

Long-term synchronous recording of brain activity in different states (rest, activity, sleep) is called EEG monitoring. Such an electroencephalogram with a frequency of once every few days or months is carried out for children who have the following conditions or diseases:

epilepsy;
sleepwalking or insomnia;
inflammatory diseases of the brain - meningoencephalitis, meningitis;
rehabilitation period after surgical interventions on the head;
cerebral palsy - the presence of motor disorders that arose in the perinatal period;
dropsy of the brain (hydrocephalus) - accumulation of excess fluid in the head;
enuresis - urinary incontinence;
autism is a painful mental condition when a child does not tolerate contact with others;
stuttering;
delayed mental or physical development;
memory impairment.

Preparing a child for an EEG

An electroencephalogram is performed in a clinic and requires some preparation. For the procedure to be successful, consider the following rules:

On the eve of the EEG, wash the child's hair with shampoo, dry well. The use of gels, styling mousses is prohibited.
Before the doctor's office, remove all metal objects from your head (earrings, hairpins, clips), loosen your hair.
If the procedure is done on an infant, feed him before starting it. Coordinate with the doctor the time of the EEG, taking into account the sleep schedule and the activity of the newborn.
For children from one year old, an encephalogram is carried out in a state of brain activity. To keep your child focused and relaxed, take their favorite book or toy with you to the office.
Do not feed your baby tightly for at least 2 hours before the procedure. For a day, strong tea, chocolate, sweets are prohibited.
If an appointment is scheduled medicines, inform the doctor in advance who will decipher the analysis. Some medications need to be canceled 1-3 days before the EEG is performed on the child.

Methods for conducting electroencephalography

Examination of the brain in children is carried out in three ways: at rest, routinely, with complete or partial sleep deprivation. All procedures are carried out according to the following scenario:

First stage- Preparation. Children from a year old are laid on a couch or seated on a chair, infants remain in their mother's arms. An electrically conductive gel is applied to the child's head, a mesh helmet is put on, or 12 electrodes are attached.

Second phase- conducting research. To exclude excessive activity of the nervous system, the room is darkened - the curtains are lowered or the lights are turned off. Turn on the device. Synchronously with the encephalogram, a video recording is made to record the movements of the patient.

Third stage- interpretation of the results. The doctor examines the record, compares its data with the age norm. Gives a conclusion about the activity of the brain and the work of the central nervous system.

routine method

The first study, which is carried out after examination by a pediatrician or neurologist. A routine encephalogram helps to establish paroxysmal conditions, to make a correct diagnosis. The procedure lasts 10-15 minutes and includes the following functional tests:

photostimulation– load on the eye with rhythmically flashing electrodes;
hyperventilation- the child is asked to take several deep breaths and slow exits;
audio stimulation- the study is carried out with a loud background sound;
with monotonous on-off light.

sleep EEG for a child

Spend during "quiet time". The technique helps to establish disturbances in the work of the brain centers that appear after falling asleep. If deep damage to the structures is suspected, diagnostics are carried out at night. Data recording begins before falling asleep and ends after natural awakening.

With sleep deprivation

An encephalogram with deprivation (decrease in sleep duration) is prescribed for children only if the previous diagnostic options did not give a detailed answer. The duration of wakefulness depends on the age of the child:

Preschool children give 4-6 hours of rest, then conduct an EEG.
Child 7-11 years old put to bed at 6-8 o'clock in the evening, and wake up at 12. The encephalogram is prescribed for 8-9 o'clock in the morning.
Children over 12 years old An EEG is done after sleep deprivation for 18 hours or more.

To facilitate the conduct of the electroencephalogram, partial deprivation is used. Extend the evening period of wakefulness by 2-3 hours and provide an early rise at 4-5 in the morning. After the procedure, the child is placed in the rest room under the supervision of medical staff.

Deciphering the EEG of the brain in children

The test results are ready the next day. The data is analyzed by a neurologist. Deciphering the EEG in children takes into account the following criteria:

Oscillation frequency. It is fixed in hertz (Hz) and describes the change in the state of the wave per second.
Range (amplitude) of curves. Recorded in microvolts (µV). Shows the gap between the peaks of waves opposite in activity.
Phase. Describes the current state of the brain.

When deciphering, the rhythm of cardiac activity and the coherence of the work of neurons of the hemispheres (right and left) are additionally taken into account. After studying all the factors and clinical symptoms, the doctor describes the activity of the brain and gives a conclusion that refutes or confirms the primary diagnosis.

Norm indicators

Rhythm is responsible for the type of brain activity. It is the main evaluation criterion. For the convenience of deciphering the results of the encephalogram, each rhythm is assigned its own letter of the Greek alphabet:

Alpha. Determined at rest. Its frequency is 8-14 Hz, the amplitude is up to 100 μV. The rhythm gradually fades away at the beginning of mental activity, opening of the eyes, exposure to external stimuli. Registered in the parietal and occipital zone.
Beta. Appears during the active state of the child, during the activation of memory, mental activity, during the experience of emotions. The normal rhythm frequency is 13-30 Hz, the range is 3-5 μV. Rhythm occurs in the zone of the central and anterior gyri.
Delta. It appears on the EEG during sleep. Registered in all parts of the brain. Frequency - 1-4 Hz, amplitude - 30-40 μV.
Theta. It is the key rhythm of sleep in children 3-6 years old. It is characterized by a frequency of 4-8 Hz and a range of 30-35 μV. Appears in the hippocampus and frontal areas of the brain.

When decoding the parameters, the age of the child is taken into account. Normally, these waves predominate:

Premature babies have peaks of delta and theta rhythms with a range of up to 25 μV, repeating every 3-15 seconds.
In full-term newborns, these indicators in the wakefulness stage are 5 Hz and 55-60 μV, at the stage of REM sleep - 5-7 Hz with a low amplitude, during restful sleep- high range of delta waves.
From the age of six months, these rhythms slowly fade away, alpha and beta waves increase.
During puberty, alpha rhythms predominate over the rest.
At the age of 18, the final formation of brain activity and stabilization of indicators take place.

Deviations from the norm and their meaning

Violation of rhythm and asymmetry of the hemispheres indicates the presence of pathologies. You can determine the type of disease by deviations in a particular rhythm. Preliminary diagnoses for deviations of the alpha wave from the norm are as follows:

increased frequency, rhythm instability - concussion, brain injury;
the absence of an alpha wave - mental retardation;
slow frequency, but normal synchrony - increased impressionability, mental excitability in a child;
absence or weakening of the alpha rhythm, a sharp jump in the wave - epilepsy, hysterical neurosis;
high amplitude, increased reaction to a deep breath, displacement of the registration point from the back of the brain - a delay in psychomotor, speech and intellectual development.

Deviations in beta parameters indicate such violations:

increased activity - nervousness, development of depression;
flash wave activity - inflammatory diseases of the brain;
rhythm frequency up to 18 Hz, amplitude above 30 μV - delayed psychomotor development;
the appearance of a beta rhythm in uncharacteristic parts of the brain - a disorder in the activity of the central nervous system (neurosis).

Violations of the delta and theta rhythm parameters indicate the following pathologies:

overestimated wave amplitude - brain tumors;
fixation of a large number of rhythms in the back of the head, an increase in frequency during hyperventilation - a delay in psychomotor development;
overestimated amplitude against the background of constant theta and delta waves - acquired oligophrenia (dementia);
sharp jumps in rhythm - neurosis;
high-frequency flashes - irritation of the brain centers that are responsible for excitability, excitement, irritation.

When deciphering the results, any nuances are taken into account. If there are deviations, the doctor pays attention to the following parameters:

Relatively rhythmic biological activity of the brain (BAE) indicates possible migraines.
BAE with paroxysms (high wave peaks) - a tendency to epilepsy, convulsive seizures.
Irritation (irritation) of individual brain structures is a violation of blood circulation. Occurs after trauma, with high intracranial pressure. Irritative changes occur with meningitis, encephalitis.
Increased response to annoying tests, paroxysm in all parts of the brain - attention deficit disorder, hyperactivity of the child.
Desynchronization or hypersynchronization of rhythms. Characteristic for diseases of the cerebral vessels of the brain.
The asymmetry of the work of the right and left hemispheres is a cyst or brain tumor.

Contraindications to the procedure

There are no absolute prohibitions on the procedure. An encephalogram of the brain is not prescribed for a child if there are open wounds on the head due to the inability to properly connect the electrodes. The procedure is also recommended to be postponed if the child has an acute infectious viral disease.

Price

You can get tested in public hospitals or private clinics, where there is special equipment. Service cost in Moscow:

European MC on the street. Shchepkin - 21300 rubles;
Family Clinic - 1280 rubles;
OJSC Medicine - 12900 rubles;
NIARMedik - 3000 rubles;
Clinical Hospital Lapino - 3900-4000 rubles;
MedikCity - 2700 rubles.

Video

Electroencephalography or EEG for short- This is one of the methods that allow you to study the human brain. This method is based on the registration of electrical impulses from the brain or some of its individual areas using a special device.

Electroencephalography allows you to identify a lot of different abnormalities and diseases with high accuracy, it is carried out quickly, painlessly and can be performed on almost any person.

The procedure can be prescribed by a specialist neuropathologist, and the procedure itself is carried out by a specialist neurophysiologist. And deciphering the indicators is the responsibility of both the first and second specialists.

Historical reference: Hans Berger is considered one of the developers of the electroencephalogram. It was he who managed in 1924 to record the first similarity of an electroencephalogram using a galvanometer (a device for measuring small currents). Later, a special device was developed, called the encephalograph, with which the procedure is carried out now.

Initially, the electroencephalogram was used only to study mental abnormalities in humans, but multiple tests have proven that the technique is also suitable for searching for other abnormalities not related to psychology.

How does electroencephalography work?

The human brain has a large number of neurons connected to each other by synaptic connections. Each neuron is a weak impulse generator.

In each area of the brain, these impulses are coordinated, while they can both strengthen and weaken each other. The created microcurrents are not stable, and their strength and amplitude can and should change.

This activity is called bioelectric. Its registration is carried out using special electrodes made of metal, which are fixed on the human head.

The electrodes capture microcurrents and transmit amplitude changes to the encephalograph device at each test time. This recording is called an electroencephalogram.

Oscillations that are recorded on paper or electronic media are called waves by specialists. They are divided into several types:

Alpha, with a frequency of 8 to 13 Hz;
Beta, with a frequency of 14 to 30 Hz;
Delta, with a frequency of up to 3 Hz;
Gamma, with a frequency of more than 30 Hz;
Theta, up to 7 Hz;

A modern encephalograph device is multichannel, what is it? This means that the instrument can capture and record all waveforms simultaneously.

The device is highly accurate (the error is minimal), the readings are reliable, and the procedure time is much shorter. The first encephalographs could capture only one wave, and testing was carried out for several hours without the possibility of stopping.

In modern medicine, 16-, 21-, 24-channel devices are used with a large set of various functions that allow for versatile checks.

Why is electroencephalography necessary?

A correctly performed electroencephalogram of the brain allows you to identify various abnormalities even on early stage development. The procedure can also help in research:

Evaluation of the nature and extent of brain dysfunction;
Studying the cycle of wakefulness and rest;
Determining the location of the focus of pathology;
Assessments of brain function between seizures;
Evaluation of the effectiveness of taking certain drugs;
Study and determination of the causes of certain psychological abnormalities such as panic attacks, epilepsy, convulsions, etc.;

Also, electroencephalography is designed to clarify the results of other tests, for example, computed tomography, if the patient suffers from neurological diseases.

The very place of injury or pathological process cannot be found using an electroencephalogram. And with attacks of various kinds, it is possible to obtain an objective assessment of the results only after some time.

Who is EEG done for?

The electroencephalogram is most commonly used by neuropathologists.

With its help, diseases such as hysterical disorders, epilepsy, etc. are successfully diagnosed. And also the data that the transcript shows allows you to identify people who, for some reason, are trying to simulate diseases.

As a rule, electroencephalography is performed:

With endocrinological diseases (,);
With convulsions;
With insomnia or sleep disorders;
With injuries to the head or vascular system in the neck and head;
After all kinds;
With migraines and other headaches, dizziness or with a constant feeling of fatigue;
With and encephalitis;
When stuttering;
With a developmental delay identified;
In case of impaired brain development for some reason (for example, with);
In various atypical cases (frequent fainting, awakenings in a dream, diencephalic crises, etc.);

There are no contraindications and restrictions to the EEG procedure. But, if the patient has heart disease or mental disorders, then an anesthesiologist is additionally invited to the electroencephalogram. And during pregnancy or during the study, children do not undergo functional tests.

New rules

In 2016 there was another change traffic rules, in addition to changing the procedure for passing the exam in the traffic police, changes were made to the procedure for obtaining a medical certificate.

The innovations are designed to increase control over candidates who want to drive, as well as to protect the passengers they will carry in the future.

According to the new rules, candidates for drivers (or those who are already driving) undergoing a medical commission for the rights of categories are subject to mandatory electroencephalography:

C. Gives the right to drive vehicles weighing more than 3.5 tons. This item includes the CE category (truck with a trailer), as well as subcategory C1 (cars weighing up to 7.5 tons) and C1E (cars weighing up to 7, 5t with trailer);
D - Buses, this item includes categories: DE (bus with a trailer), D1 (bus for up to 16 people) and subcategory D1E (bus for up to 16 people with a trailer);
Tm. Gives the right to drive a tram. It is possible to open a category only after special training and not earlier than 21 years old;
Tb. The right to drive trolleybuses. The order of receipt is similar to the Tm category;

These innovations also apply to other candidates or drivers undergoing a medical commission, but an electroencephalogram is not necessary for them and plays the role of an additional examination to which they can be sent.

Both a psychiatrist and a neurologist can do this. A referral is issued only if there are clinical symptoms or various kinds of disease syndromes in which it is forbidden to drive.

Such diseases, according to the rules, include chronic mental disorders, epilepsy, diseases of the nervous system or head trauma.

How to prepare for an EEG?

There are no special strict rules or restrictions before the procedure, however, there are a number of rules that are recommended to be followed:

Only the supervising physician can make a decision to cancel or change the dosage of drugs;
At least 12 hours before the procedure (preferably 24 hours before), it is not recommended to take foods containing caffeine, carbonated drinks, products with chocolate or cocoa, or other energy components, such as taurine. The same rule applies to taking drugs and products of the opposite, calming effect;
The head of the person who will have an electroencephalogram should be washed. It is not recommended to use additional products such as oils, balms, varnishes, etc. This may complicate the study, since the contact of the electrodes will be insufficient;
If the study is aimed at studying convulsive activity, then before its implementation it is necessary to sleep;
To obtain a reliable result, the patient should not be nervous and worried, and it is also not recommended to drive at least 12 hours before the study;
It is recommended to eat a couple of hours before the procedure;

The child should not have hairstyles, earrings and other jewelry;
The head must be clean and the hair dry;
The child must be calm. A game form of the procedure or a calm conversation with the child will come to the aid of parents;
The child should be aware that the procedure is simple and painless, as well as that the doctor may ask the child to perform certain actions and he needs to obey;
The child should not be hungry;
For young patients, the use of food or toys as a means of sedation is allowed;

Without following the above rules, the result, which shows the EEG of the brain , may not be accurate, and the procedure itself will be recommended to be repeated.

How is the EEG done?

An electroencephalogram is usually taken during the day, but in some cases it may be done at night (sleep studies). The holding time is from 40 - 45 minutes to 2 hours during the day or from 1 to 24 hours in the form of monitoring.

The room for the study is used isolated from light and extraneous sounds. Communication with the patient is carried out using a microphone, and the study itself is most often recorded on camera.

Put on the patient's head special device with electrodes, made in the likeness of a regular cap. A special, conductive gel is applied under the cap to the hair or scalp, which allows you to fix the electrodes in their places and increase their sensitivity. After that, the patient takes a comfortable position for himself, sitting or lying down.

During the study, the patient may be asked to blink several times or simply open his eyes, this is necessary to assess the work of the brain when the eyes work. During the examination, the patient's eyes are closed.

It is permissible to suspend the diagnosis if, for some reason, a person needs it.

A large number of questions from parents are caused by EEG in children. The procedure itself is not dangerous even for newborns.

The registered microcurrents are so small that their detection and recording is possible only with the help of an amplifier. And the gel that is used to improve the contact between the electrodes and the scalp is hypoallergenic and is made only on a water basis.

Conducting a study in children is not much different from conducting an EEG in an adult. Babies up to a year are in the arms of their mother, and the procedure itself is carried out only when the child is sleeping.

Older children are laid on the couch. The procedure time is reduced, usually it is no more than 20-30 minutes. And if it becomes necessary to take samples, then it will not be superfluous for parents to take their favorite food, toy or milk with them in order to calm the baby.

How to decrypt?

EEG decoding, what is it? The very concept of decoding means recording the result understandable only to the doctor in a form understandable to the patient and other specialists.

The decoding of the electroencephalogram shows several types of waves in one or more diagrams. The regularity of the waves is provided by the work of a part of the brain called the thalamus. It is responsible for their generation and synchrony, and is also responsible for the functioning of the central nervous system as a whole.

Each wave, which shows the EEG of the brain, has its own characteristics and reflects a certain type of brain activity. Eg:

Alpha waves help track the work of the brain in the waking state (with eyes closed), a regular rhythm is considered normal. The strongest signal is recorded in the parietal and occipital regions;
Beta waves are responsible for anxiety, depression or anxiety, as well as these waves evaluate the effectiveness of taking sedatives;
Theta waves are responsible for sleep (natural), in children this type of waves is predominant over all others;
With the help of delta waves, the presence of pathology is diagnosed, as well as a search for the approximate location of its deployment;

When analyzing the data, the doctor must take into account many factors, including the symmetry of the signal and the possible error in the indicators (depending on the device), as well as the results of functional tests (reaction to light, blinking and slow breathing).

EEG readings can vary greatly depending on the state of the person, for example, a sleeping person will have slower rhythms than a person at rest, and when stimuli or even extraneous thoughts appear, the amplitude of the waves can increase dramatically. Therefore, the rule of the absence of nervous tension is extremely important and that is why it is not recommended to drive for some time before the EEG.

The conclusion of specialists is based on the analysis of the data of each of the waves and their overall picture. Rhythm, frequency, and amplitude are analyzed and evaluated, taking into account other patient data and video recordings of the study. In the conclusion of a specialist, there should be several mandatory points:

Characteristics of EEG waves and their activity;
The medical report itself and its interpretation;
Indication of the correspondence between the EEG pattern and the patient's symptoms;

The final diagnosis is determined only in the presence of symptoms that bother the patient. For example, if the EEG showed sharp changes in alpha wave rhythms and the patient has pain or fainting, then this may be the result of a head injury, if there is no rhythm at all, then this may indicate dementia and other mental disorders.

Possible causes of violations

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

Timely conduct of the EEG of the brain and competent decoding of the results will help to establish a diagnosis in case of violations and prescribe adequate therapy for brain diseases.

Electroencephalography (EEG) - modern method diagnosis of brain diseases in children and adult patients. Such a procedure is based on recording the electrical activity of individual parts of the CNS (central nervous system), which makes it possible to assess their condition and functional activity. When conducting an EEG of the brain, deciphering the indicators is the most important step, since the diagnosis and appointment of subsequent treatment depend on this. A neurologist who has undergone special training should interpret the data obtained on the electroencephalogram. Otherwise, it is possible to use inappropriate drugs, which can lead to various complications and side effects medicines.

During the EEG, the patient should be in a calm state.

About method

EEG is a diagnostic procedure based on recording the activity of brain regions. This becomes possible due to the use of precise electrodes that allow recording the functional state of various groups of neurons. At the same time, the procedure can be performed at different ages with a wide range of diseases, including neuroinfections, infectious and non-infectious encephalitis and meningitis, epilepsy, etc. The technique allows to identify the presence and degree of brain damage.

The procedure is carried out in accordance with a special protocol, which includes various functional tests:

Exposure to flashes of bright light, or photostimulation. It is important to note that at this point the patient must keep his eyes closed.
Alternate eye opening and closing test.
A breath test that assesses the state of the central nervous system during hyperventilation.

Special tests allow for a more complete study of the functions of various parts of the brain. At the same time, a number of doctors, in order to obtain accurate results, use additional actions on the part of the patient, for example, squeezing the fingers on the hand or staying in the dark for a long time. In addition, drug tests, daily monitoring of brain activity, etc. are possible. All this is necessary for the subsequent decoding of the EEG of the brain in order to make a correct diagnosis.

Conducting research

When conducting a diagnostic analysis of brain activity, EEG must be carried out in a special room that excludes any external stimuli on the patient, including visual and sound stimuli. The patient can sit or lie down while taking the encephalogram. Analysis of the activity of neurons occurs thanks to a special cap with several dozen electrodes, which are sensors.

These sensors are lubricated with a special conductive gel, which allows you to get clearer results, facilitating the subsequent decoding of the EEG. Depending on the need for additional tests, the duration of the study can vary from 15 minutes to twenty-four hours.

Correct decoding of the EEG in an adult requires compliance with the standard protocol of the procedure. To do this, before starting the study, the doctor must talk to the patient and explain to him the essence of the upcoming procedure, as well as possible indicators that reflect the norm or pathology of the brain.

In the process of taking the EEG, the patient should not move, keep his eyes constantly closed and follow all incoming instructions from the doctor.

EEG rhythms in a healthy person

The main types of rhythms observed during the EEG

The activity of brain neurons is recorded as a certain rhythm, which depends on the work of the subcortical and cortical parts of the CNS. As a rule, four types of rhythms can be determined in a healthy person:

The alpha rhythm corresponds to the state of rest during wakefulness. It is important to note that at the same time, the person's eyes must be closed. The average frequency of such a rhythm is 8-14 Hz. With any physical activity, the alpha rhythm changes.
The beta rhythm is characteristic of a state of arousal, when a person experiences fear, anxiety, and any other negative emotions. The pulse frequency in this case ranges from 13 to 30 Hz.
Theta rhythm is associated with rare impulses (4-7 Hz) and is of low amplitude. It corresponds to natural sleep and is most common in children.
The delta rhythm has an even lower frequency (up to 3 Hz) and is also characteristic of the sleep period. A similar form of activity occurs during wakefulness, however, quite rarely.

The picture of the resulting rhythms should be deciphered only by a neurologist. When trying to interpret it yourself, errors and incorrect conclusions are possible, which can be harmful to the patient.

Deciphering the results

Patients often ask themselves the question - they underwent an electroencephalogram of the brain, what does the decoding of this study show? Such an analysis allows the doctor to assess the state and activity of various parts of the brain, which is necessary to detect diseases.

To decipher an electroencephalogram, a doctor must have a certain qualification

It becomes possible to identify changes and disturbances in the activity of the central nervous system by assessing the rhythm of excitation, comparing data obtained from symmetrical parts of the brain, as well as by analyzing the results of special functional tests with photostimulation, hyperventilation, etc.

If EEG decoding is required in children (suspected autism, epilepsy, etc.), then, due to the insufficient maturity of the structures of the central nervous system, a number of studies are required to compare the results with each other. This approach makes it possible to suspect diseases at an early age.

Various features of the patient's body or external influences can change the results obtained, affecting the conclusion of the EEG. These include:

Patient's age.
Presence of comorbidities.
Tremor and other changes in the motor sphere.
Visual disturbances.
Taking medications that affect the nervous system. Similar changes are observed with the use of drinks containing caffeine.
Any changes in the electrical conductivity of the skin, which can be observed with its increased fat content, etc.

The attending physician must take into account these factors when compiling the results and conclusion of the EEG. If you suspect errors in the process of conducting the study, it is better to repeat it.

Possible deviations in the results

The final diagnosis is made only taking into account the clinical symptoms that disturb the patient

Doctors are well aware of how to decipher the EEG and what changes this technique can show. It is important to note that not every doctor is able to provide a correct interpretation of the results, and therefore, patients should only contact specialists.

There is a large number options deviations, which may be moderate or severe, depending on the degree of CNS damage. The main changes on the electroencephalogram include:

Disturbances in the coordination of the work of the central nervous system structures located in different hemispheres. This can be observed with damage to the conduction pathways or local impact on a group of neurons.
The appearance of sudden bursts of activity or their suppression may indicate an infectious lesion of the nervous system, the development of a tumor process, a traumatic brain injury, or various types of stroke.
The appearance of rhythms with high amplitude, irregular shape, as well as in the form of multiple repetitions, reflects diffuse disturbances in the activity of neurons, which can occur in epilepsy.
When awake, delta and theta rhythms should not be detected in a normal person. If they are detected, then this indicates a violation of the central nervous system.
A significant decrease in brain activity is observed in patients in a coma.

In addition to these obvious deviations, the doctor can indicate in his conclusion changes in individual rhythms that are observed in healthy people. Such deviations are characterized by an increase in the frequency or amplitude of individual rhythms and reflect damage to the structures of the central nervous system of an organic or functional nature.

Electroencephalograms in normal and epileptic seizures

In some patients, in the form of a medical report on the decoding of the EEG, there are additional signs of impaired brain function:

Paroxysmal changes, mainly indicating a severe headache that persists constantly. There is also evidence that such paroxysms may reflect the patient's predisposition to epileptic seizures.
When the EEG is deciphered, the doctor can pay attention to the foci of constant excitation of neurons - they can become the site of the onset of epileptic activity in a patient at any age.
A decrease in activity, up to the disappearance, of neurons in certain structures of the brain indicates their serious damage, which can occur with strokes, traumatic brain injuries, etc.

The obtained values of the electroencephalogram make it possible to make an accurate diagnosis of the CNS lesion, which is necessary for the choice of further diagnostic and therapeutic tactics. Possible deviations should be carefully analyzed, comparing, if possible, the picture of changes with previous survey results.

Electroencephalography is an indispensable diagnostic tool for many neurological diseases, such as epilepsy. A neurologist can interpret the results and determine the presence and extent of brain damage without the use of invasive diagnostic methods. The procedure can be performed at any age, including infants.