Features of children's EEG. Age-related features of frequency-specific characteristics of EEG Fefilov Anton Valerievich. Failures of bioelectrical activity

Using the method of electroencephalography (abbreviation EEG), along with computer or magnetic resonance imaging (CT, MRI), the activity of the brain and the state of its anatomical structures are studied. The procedure plays a huge role in identifying various anomalies by studying the electrical activity of the brain.

EEG is an automatic recording of the electrical activity of neurons in brain structures, performed using electrodes on special paper. Electrodes are attached to various areas of the head and record brain activity. In this way, the EEG is recorded in the form of a background curve of the functionality of the structures of the thinking center in a person of any age.

A diagnostic procedure is performed for various lesions of the central nervous system, for example, dysarthria, neuroinfection, encephalitis, meningitis. The results allow us to evaluate the dynamics of the pathology and clarify the specific location of the damage.

The EEG is carried out in accordance with a standard protocol that monitors activity during sleep and wakefulness, with special tests for the activation response.

For adult patients, diagnosis is carried out in neurological clinics, departments of city and regional hospitals, and a psychiatric clinic. To be confident in the analysis, it is advisable to contact an experienced specialist working in the neurology department.

For children under 14 years of age, EEGs are performed exclusively in specialized clinics by pediatricians. Psychiatric hospitals do not perform the procedure on young children.

What do EEG results show?

An electroencephalogram shows the functional state of brain structures during mental and physical stress, during sleep and wakefulness. This is an absolutely safe and simple method, painless, and does not require serious intervention.

Today, EEG is widely used in the practice of neurologists in the diagnosis of vascular, degenerative, inflammatory brain lesions, and epilepsy. The method also allows you to determine the location of tumors, traumatic injuries, and cysts.

EEG with the impact of sound or light on the patient helps to express true visual and hearing impairments from hysterical ones. The method is used for dynamic monitoring of patients in intensive care units in a coma state.

Norm and disorders in children

1. EEG for children under 1 year of age is performed in the presence of the mother. The child is left in a sound- and light-proof room, where he is placed on a couch. Diagnostics takes about 20 minutes.
2. The baby's head is wetted with water or gel, and then a cap is put on, under which the electrodes are placed. Two inactive electrodes are placed on the ears.
3. Using special clamps, the elements are connected to wires suitable for the encephalograph. Due to the low current, the procedure is completely safe even for infants.
4. Before monitoring begins, the child's head is positioned level so that there is no forward bending. This may cause artifacts and skew the results.
5. EEGs are done on infants during sleep after feeding. It is important to let the boy or girl get enough immediately before the procedure so that he falls asleep. The mixture is given directly in the hospital after a general medical examination.
6. For children under 3 years old, an encephalogram is taken only in a state of sleep. Older children may remain awake. To keep the child calm, they give him a toy or a book.

An important part of the diagnosis are tests with opening and closing the eyes, hyperventilation (deep and rare breathing) with EEG, squeezing and unclenching of the fingers, which allows disorganization of the rhythm. All tests are conducted in the form of a game.

After receiving the EEG atlas, doctors diagnose inflammation of the membranes and structures of the brain, latent epilepsy, tumors, dysfunction, stress, and fatigue.

The degree of delay in physical, mental, mental, speech development is carried out using photostimulation (blinking a light bulb with eyes closed).

EEG values ​​in adults

For adults, the procedure is carried out subject to the following conditions:

• keep your head motionless during manipulation, eliminate any irritating factors;
• Before diagnosis, do not take sedatives or other drugs that affect the functioning of the hemispheres (Nerviplex-N).

Before the manipulation, the doctor conducts a conversation with the patient, putting him in a positive mood, calming him down and instilling optimism. Next, special electrodes connected to the device are attached to the head, and they read the readings.

The examination lasts only a few minutes and is completely painless.

Provided that the rules described above are observed, even minor changes in the bioelectrical activity of the brain are determined using EEG, indicating the presence of tumors or the onset of pathologies.

Electroencephalogram rhythms

An electroencephalogram of the brain shows regular rhythms of a certain type. Their synchrony is ensured by the work of the thalamus, which is responsible for the functionality of all structures of the central nervous system.

The EEG contains alpha, beta, delta, tetra rhythms. They have different characteristics and show certain degrees of brain activity.

Alpha - rhythm

The frequency of this rhythm varies in the range of 8-14 Hz (in children from 9-10 years old and adults). It appears in almost every healthy person. The absence of alpha rhythm indicates a violation of the symmetry of the hemispheres.

The highest amplitude is characteristic in a calm state, when a person is in a dark room with his eyes closed. When thinking or visual activity is partially blocked.

A frequency in the range of 8-14 Hz indicates the absence of pathologies. The following indicators indicate violations:

• alpha activity is recorded in the frontal lobe;
• asymmetry of the interhemispheres exceeds 35%;
• the sinusoidality of the waves is disrupted;
• there is a frequency scatter;
• polymorphic low-amplitude graph less than 25 μV or high (more than 95 μV).

Alpha rhythm disturbances indicate a possible asymmetry of the hemispheres due to pathological formations (heart attack, stroke). A high frequency indicates various types of brain damage or traumatic brain injury.

In a child, deviations of alpha waves from the norm are signs of mental retardation. In dementia, alpha activity may be absent.

Normally, polymorphic activity is within the range of 25–95 μV.

Beta activity

The beta rhythm is observed in the borderline range of 13-30 Hz and changes when the patient is active. With normal values, it is expressed in the frontal lobe and has an amplitude of 3-5 µV.

High fluctuations give grounds to diagnose a concussion, the appearance of short spindles - encephalitis and a developing inflammatory process.

In children, the pathological beta rhythm manifests itself at an index of 15-16 Hz and an amplitude of 40-50 μV. This signals a high probability of developmental delay. Beta activity may dominate due to the use of various medications.

Theta rhythm and delta rhythm

Delta waves appear in deep sleep and in coma. They are recorded in areas of the cerebral cortex bordering the tumor. Rarely observed in children 4-6 years old.

Theta rhythms range from 4-8 Hz, are produced by the hippocampus and are detected during sleep. With a constant increase in amplitude (over 45 μV), they speak of a dysfunction of the brain.

If theta activity increases in all departments, we can argue about severe pathologies of the central nervous system. Large fluctuations indicate the presence of a tumor. High levels of theta and delta waves in the occipital region indicate childhood lethargy and developmental delays, and also indicate poor circulation.

BEA - Bioelectric activity of the brain

EEG results can be synchronized into a complex algorithm - BEA. Normally, the bioelectrical activity of the brain should be synchronous, rhythmic, without foci of paroxysms. As a result, the specialist indicates which violations have been identified and based on this, an EEG conclusion is made.

Various changes in bioelectrical activity have an EEG interpretation:

• relatively rhythmic BEA – may indicate the presence of migraines and headaches;
• diffuse activity is a variant of the norm, provided there are no other abnormalities. In combination with pathological generalizations and paroxysms, it indicates epilepsy or a tendency to seizures;
• decreased BEA may signal depression.

Other indicators in the conclusions

How to learn to independently interpret expert opinions? Decoding of EEG indicators is presented in the table:

Online consultations with specialists in the field of medicine help people understand how certain clinically significant indicators can be deciphered.

Reasons for violations

Electrical impulses ensure rapid transmission of signals between neurons in the brain. Violation of conduction function affects health. All changes are recorded in bioelectrical activity during an EEG.

There are several reasons for BEA violations:

• injuries and concussions - the intensity of the changes depends on the severity. Moderate diffuse changes are accompanied by mild discomfort and require symptomatic therapy. Severe injuries are characterized by severe damage to impulse conduction;
• inflammation involving the brain and cerebrospinal fluid. BEA disorders are observed after meningitis or encephalitis;
• vascular damage by atherosclerosis. At the initial stage, the disturbances are moderate. As tissue dies due to lack of blood supply, the deterioration of neural conduction progresses;
• irradiation, intoxication. With radiological damage, general disturbances of the BEA occur. Signs of toxic poisoning are irreversible, require treatment, and affect the patient's ability to perform daily tasks;
• associated disorders. Often associated with severe damage to the hypothalamus and pituitary gland.

EEG helps to identify the nature of BEA variability and prescribe appropriate treatment that helps activate biopotential.

Paroxysmal activity

This is a recorded indicator indicating a sharp increase in the amplitude of the EEG wave, with a designated source of occurrence. This phenomenon is believed to be associated only with epilepsy. In fact, paroxysm is characteristic of various pathologies, including acquired dementia, neurosis, etc.

In children, paroxysms can be a variant of the norm if there are no pathological changes in the structures of the brain.


During paroxysmal activity, the alpha rhythm is mainly disrupted. Bilaterally synchronous flashes and oscillations are manifested in the length and frequency of each wave in a state of rest, sleep, wakefulness, anxiety, and mental activity.

Paroxysms look like this: pointed flashes predominate, which alternate with slow waves, and with increased activity, so-called sharp waves (spikes) appear - many peaks coming one after another.

Paroxysm with EEG requires additional examination by a therapist, neurologist, psychotherapist, a myogram and other diagnostic procedures. Treatment consists of eliminating causes and consequences.

In case of head injuries, the damage is eliminated, blood circulation is restored and symptomatic therapy is carried out. For epilepsy, they look for what caused it (tumor, etc.). If the disease is congenital, the number of seizures, pain and negative effects on the psyche are minimized.

If paroxysms are a consequence of problems with blood pressure, treatment of the cardiovascular system is carried out.

Dysrhythmia of background activity

It means irregular frequencies of electrical brain processes. This occurs due to the following reasons:

1. Epilepsy of various etiologies, essential hypertension. There is asymmetry in both hemispheres with irregular frequency and amplitude.
2. Hypertension - the rhythm may decrease.
3. Oligophrenia – ascending activity of alpha waves.
4. Tumor or cyst. There is an asymmetry between the left and right hemispheres of up to 30%.
5. Circulatory disorders. The frequency and activity decreases depending on the severity of the pathology.

To assess dysrhythmia, indications for an EEG are diseases such as vegetative-vascular dystonia, age-related or congenital dementia, and traumatic brain injury. The procedure is also carried out in case of high blood pressure, nausea, and vomiting in humans.

Irritative changes on EEG

This form of disorder is predominantly observed in tumors with a cyst. It is characterized by general cerebral EEG changes in the form of diffuse cortical rhythms with a predominance of beta oscillations.

Also, irritative changes can occur due to pathologies such as:

• meningitis;
• encephalitis;
• atherosclerosis.

What is disorganization of cortical rhythmicity?

They appear as a consequence of head injuries and concussions, which can cause serious problems. In these cases, the encephalogram shows changes occurring in the brain and subcortex.

The patient’s well-being depends on the presence of complications and their severity. When insufficiently organized cortical rhythms dominate in a mild form, this does not affect the patient’s well-being, although it may cause some discomfort.

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

Electroencephalogram of the brain - definition and essence of the method

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

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

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

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

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

What does an electroencephalogram show?

Today, the electroencephalogram is widely used in the practice of neurologists, since this method makes it possible to diagnose epilepsy, vascular, inflammatory and degenerative lesions of the brain. In addition, EEG helps to determine the specific location of tumors, cysts and traumatic damage to brain structures.

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

Where and how to do it?

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

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

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

Electroencephalogram for children: how the procedure is performed

To record an EEG, a cap is placed on the baby's head, under which the doctor places electrodes. The skin under the electrodes is wetted with water or gel. Two inactive electrodes are placed on the ears. Then, using alligator clips, the electrodes are connected to the wires connected to the device - the encephalograph. Since electrical currents are very small, an amplifier is always needed, otherwise brain activity will simply not be recorded. It is the small current strength that is the key to the absolute safety and harmlessness of EEG, even for infants.

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

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

Electroencephalogram rhythms

The human EEG contains alpha, beta, delta and theta rhythms, which have different characteristics and reflect certain types of brain activity.

Alpha rhythm has a frequency of 8 – 14 Hz, reflects a state of rest and is recorded in a person who is awake, but with his eyes closed. This rhythm is normally regular, the maximum intensity is recorded in the area of ​​the back of the head and the crown. The alpha rhythm ceases to be detected when any motor stimuli appear.

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

Theta rhythm has a frequency of 4–7 Hz and an amplitude of 25–35 μV, reflecting the state of natural sleep. This rhythm is a normal component of the adult EEG. And in children this type of rhythm on the EEG predominates.

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

Electroencephalogram results

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

Decoding the electroencephalogram

Decoding the electroencephalogram involves interpreting the conclusion. Let's consider the basic concepts that the doctor reflects in the conclusion and their clinical significance (that is, what these or those parameters can indicate).

Alpha - rhythm

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

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

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

About delayed psycho-motor development in children they say:

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

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

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

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

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

Beta rhythm

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

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

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

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

Theta rhythm and delta rhythm

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

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

Synchronous theta rhythm, delta waves in all parts of the brain, bursts of bilateral synchronous theta waves with high amplitude, paroxysms in the central parts of the brain - indicate acquired dementia.

The predominance of theta and delta waves on the EEG with maximum activity in the occipital region, flashes of bilateral synchronous waves, the number of which increases with hyperventilation, indicates a delay in the psychomotor development of the child.

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

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

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

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

Bioelectric activity of the brain (BEA)

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

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

Other indicators

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

Diffuse disorganization of the alpha rhythm, activation of diencephalic-stem structures of the brain against the background of tests (hyperventilation, closing-opening of eyes, photostimulation) is the norm, if the patient has no complaints.

Center of pathological activity indicates increased excitability of this area, which indicates a tendency to seizures or the presence of epilepsy.

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

Paroxysms They talk about increased excitation and decreased inhibition, which is often accompanied by migraines and simple headaches. In addition, there may be a tendency to develop epilepsy or the presence of this pathology if a person has had seizures in the past.

Reducing the threshold for seizure activity indicates a predisposition to seizures.

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

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

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

Epileptiform activity indicates the development of epilepsy and an increased tendency to seizures.

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

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

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

Disturbance of brain wave activity (appearance of beta activity in all parts of the brain, dysfunction of midline structures, theta waves) occurs after traumatic injuries, and can manifest itself as dizziness, loss of consciousness, etc.

Organic changes in brain structures in children are a consequence of infectious diseases such as cytomegalovirus or toxoplasmosis, or hypoxic disorders that occur during childbirth. A comprehensive examination and treatment is necessary.

Regulatory cerebral changes are registered in hypertension.

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

In case of brain tumors, the following are detected:

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

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

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

Significant slowing of alpha rhythm may accompany parkinsonism. Fixation of theta and delta waves in the frontal and anterior temporal parts of the brain, which have different rhythms, low frequencies and high amplitudes, is possible in Alzheimer's disease

Age-related changes in the bioelectrical activity of the brain cover a significant period of ontogenesis from birth to adolescence. Based on many observations, signs have been identified by which one can judge the maturity of the bioelectrical activity of the brain. These include: 1) features of the frequency-amplitude spectrum of the EEG; 2) the presence of stable rhythmic activity; 3) average frequency of the dominant waves; 4) EEG features in different areas of the brain; 5) features of generalized and local evoked brain activity; 6) features of the spatio-temporal organization of brain biopotentials.

The most studied in this regard are age-related changes in the frequency-amplitude spectrum of the EEG in different areas of the cerebral cortex. Newborns are characterized by irregular activity with an amplitude of about 20 µV and frequency 1-6 Hz The first signs of rhythmic orderliness appear in the central zones starting from the third month of life. During the first year of life, an increase in the frequency and stabilization of the basic rhythm of the child’s EEG is observed. The tendency towards an increase in the dominant frequency continues at further stages of development. By the age of 3 this is already a rhythm with a frequency of 7-8 Hz, by 6 years - 9-10 Hz etc. . At one time it was believed that each EEG frequency band dominates in ontogenesis one after another. According to this logic, 4 periods were distinguished in the formation of bioelectrical activity of the brain: 1st period (up to 18 months) - dominance of delta activity, mainly in the central-parietal leads; 2nd period (1.5 years - 5 years) - dominance of theta activity; 3rd period (6-10 years) - dominance of alpha activity (labile

phase); 4th period (after 10 years of life) - dominance of alpha activity (stable phase). In the last two periods, maximum activity occurs in the occipital regions. Based on this, it was proposed to consider the ratio of alpha and theta activity as an indicator (index) of brain maturity.

However, the problem of the relationship between theta and alpha rhythms in ontogenesis is a subject of debate. According to one view, the theta rhythm is considered as a functional precursor of the alpha rhythm, and thus it is recognized that in the EEG of young children the alpha rhythm is virtually absent. Researchers who adhere to this position consider it unacceptable to consider the rhythmic activity dominant in the EEG of young children as the alpha rhythm; from the perspective of others, the rhythmic activity of infants is in the range of 6-8 Hz in its functional properties it is analogous to the alpha rhythm.

In recent years, it has been established that the alpha range is heterogeneous, and in it, depending on the frequency, a number of subcomponents can be distinguished that apparently have different functional significance. A significant argument in favor of identifying narrow-band alpha subbands is the ontogenetic dynamics of their maturation. The three sub-bands include: alpha 1 - 7.7-8.9 Hz; alpha 2 - 9.3-10.5 Hz; alpha 3 - 10.9-12.5 Hz. From 4 to 8 years, alpha 1 dominates, after 10 years, alpha 2 dominates, and by 16-17 years, alpha 3 predominates in the spectrum.

Studies of age-related EEG dynamics are carried out at rest, in other functional states (soya, active wakefulness, etc.), as well as under the influence of various stimuli (visual, auditory, tactile).

Study of sensory-specific brain reactions to stimuli of different modalities, i.e. EP shows that local brain responses in the projection zones of the cortex are recorded from the moment the child is born. However, their configuration and parameters indicate different degrees of maturity and discrepancies with those of an adult in different modalities. For example, in the projection zone of a functionally more significant and morphologically more mature somatosensory analyzer at the time of birth, EPs contain the same components as in adults, and their parameters reach maturity already in the first weeks of life. At the same time, visual and auditory EPs are much less mature in newborns and infants.

The visual EP of newborns is a positive-negative oscillation recorded in the projection occipital region. The most significant changes in the configuration and parameters of such VPs occur in the first two years of life. During this period, EPs per flash are transformed from a positive-negative oscillation with a latency of 150-190 ms into a multicomponent reaction, which in general terms persists in further ontogenesis. Final stabilization of the component composition of such VPs

occurs by the age of 5-6 years, when the main parameters of all components of visual EP to a flash are within the same limits as in adults. The age-related dynamics of EPs to spatially structured stimuli (chess fields, gratings) differs from responses to a flash. The final design of the component composition of these VPs occurs up to 11-12 years.

Endogenous, or “cognitive,” components of EP, reflecting the provision of more complex aspects of cognitive activity, can be recorded in children of all ages, starting from infancy, but at each age they have their own specifics. The most systematic facts were obtained in the study of age-related changes in the P3 component in decision-making situations. It has been established that in the age range from 5-6 years to adulthood there is a reduction in the latent period and a decrease in the amplitude of this component. It is assumed that the continuous nature of changes in these parameters is due to the fact that common generators of electrical activity operate at all ages.

Thus, the study of EP ontogenesis opens up opportunities for studying the nature of age-related changes and continuity in the functioning of the brain mechanisms of perceptual activity.

ONTOGENETIC STABILITY OF EEG AND EP PARAMETERS

The variability of bioelectrical activity of the brain, like other individual traits, has two components: intra-individual and inter-individual. Intra-individual variability characterizes the reproducibility (test-retest reliability) of EEG and EP parameters in repeated studies. Under constant conditions, the reproducibility of EEG and EP in adults is quite high. In children, the reproducibility of the same parameters is lower, i.e. they are distinguished by significantly greater intra-individual variability of EEG and EP.

Individual differences between adult subjects (interindividual variability) reflect the work of stable nervous formations and are largely determined by genotype factors. In children, interindividual variability is due not only to individual differences in the functioning of already established nervous structures, but also to individual differences in the rate of maturation of the central nervous system. Therefore, in children it is closely related to the concept of ontogenetic stability. This concept does not imply the absence of changes in the absolute values ​​of maturation indicators, but the relative constancy of the rate of age-related transformations. The degree of ontogenetic stability of a particular indicator can only be assessed in longitudinal studies that compare the same indicators in the same children at different stages of ontogenesis. Evidence of ontogenetic stability

The strength of the sign can be determined by the constancy of the ranking place that the child occupies in the group during repeated examinations. To assess ontogenetic stability, Spearman's rank correlation coefficient is often used, preferably adjusted for age. Its value does not indicate the constancy of the absolute values ​​of a particular characteristic, but rather the fact that the subject maintains his rank place in the group.

Thus, individual differences in EEG and EP parameters in children and adolescents compared with individual differences in adults have, relatively speaking, a “double” nature. They reflect, firstly, individually stable features of the functioning of nerve formations and, secondly, differences in the rate of maturation of the brain substrate and psychophysiological functions.

There is little experimental data indicating the ontogenetic stability of the EEG. However, some information about this can be obtained from works devoted to the study of age-related changes in the EEG. In Lindsley's well-known work [cit. according to: 33] children from 3 months to 16 years were studied, and the EEG of each child was monitored for three years. Although the stability of individual characteristics was not specifically assessed, data analysis allows us to conclude that, despite natural age-related changes, the subject's ranking position is approximately maintained.

It has been shown that some EEG characteristics are stable over long periods of time, despite the process of EEG maturation. In the same group of children (13 people), the EEG and its changes during indicative and conditioned reflex reactions in the form of depression of the alpha rhythm were recorded twice, with an interval of 8 years. At the time of the first registration, the average age of the subjects in the group was 8.5 years; during the second - 16.5 years, the rank correlation coefficients for total energies were: in the delta and theta rhythm bands - 0.59 and 0.56; in the alpha rhythm band -0.36, in the beta rhythm band -0.78. Similar correlations for frequencies turned out to be no lower, but the highest stability was found for the alpha rhythm frequency (R = 0.84).

In another group of children, assessment of the ontogenetic stability of the same background EEG indicators was carried out with a break of 6 years - at 15 years and 21 years. In this case, the most stable were the total energies of slow rhythms (delta and theta) and alpha rhythms (correlation coefficients for all - about 0.6). In terms of frequency, the alpha rhythm again demonstrated maximum stability (R = 0.47).

Thus, judging by the rank correlation coefficients between two series of data (1st and 2nd examinations) obtained in these studies, it can be stated that parameters such as alpha rhythm frequency, total energies of delta and theta rhythms and a number of other EEG indicators turn out to be individually stable.

Interindividual and intraindividual variability of EP in ontogenesis has been studied relatively little. However, one fact is beyond doubt: with age, the variability of these reactions decreases.

The individual specificity of the configuration and parameters of the VP is increasing and increasing. Available estimates of test-retest reliability of the amplitudes and latent periods of visual EPs, the endogenous P3 component, as well as movement-related brain potentials generally indicate a relatively low level of reproducibility of the parameters of these reactions in children compared to adults. The corresponding correlation coefficients vary over a wide range, but do not rise above 0.5-0.6. This circumstance significantly increases the measurement error, which, in turn, can affect the results of genetic statistical analysis; as noted, measurement error is included in the assessment of the individual environment. Nevertheless, the use of certain statistical techniques allows in such cases to introduce the necessary corrections and increase the reliability of the results.

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Video: Magnetoencephalography (MEG) - Tatyana Strogonova

11
NORMAL AND PATHOLOGICAL ELECTROENCEPHALOGRAMS OF CHILDREN
AGE FEATURES OF EEG OF HEALTHY CHILDREN
The EEG of a child is significantly different from the EEG of an adult. In the process of individual development, the electrical activity of various areas of the cortex undergoes a number of significant changes due to the heterochronicity of maturation of the cortex and subcortical formations and the varying degrees of participation of these brain structures in the formation of the EEG.
Among the numerous studies in this direction, the most fundamental are the works of Lindsley (1936), F. Gibbs and E. Gibbs (1950), G. Walter (1959), Lesny (1962), L. A. Novikova
, N. N. Zislina (1968), D. A. Farber (1969), V. V. Alferova (1967), etc.
A distinctive feature of the EEG of young children is the presence of slow forms of activity in all parts of the hemispheres and the weak expression of regular rhythmic oscillations, which occupy the main place on the EEG of an adult.
The waking EEG of newborns is characterized by the presence of low-amplitude oscillations of various frequencies in all areas of the cortex.
In Fig. 121, A shows an EEG of a child recorded on the 6th day after birth. There is no dominant rhythm in all parts of the hemispheres. Low-amplitude asynchronous delta waves and single theta oscillations are recorded with low-voltage beta oscillations preserved against their background. During the neonatal period, during the transition to sleep, an increase in the amplitude of biopotentials and the appearance of groups of rhythmic synchronized waves with a frequency of 4-6 Hz are observed.
With age, rhythmic activity occupies an increasing place on the EEG and is more persistently manifested in the occipital areas of the cortex. By 1 year, the average frequency of rhythmic oscillations in these parts of the hemispheres is from 3 to 6 Hz, and the amplitude reaches 50 μV. At the age of 1 to 3 years, the child’s EEG shows a further increase in the frequency of rhythmic oscillations. In the occipital areas, oscillations with a frequency of 5-7 Hz predominate, while the number of oscillations with a frequency of 3-4 Hz decreases. Slow activity (2-3 Hz) is consistently evident in the anterior parts of the hemispheres. At this age, the EEG shows the presence of frequent oscillations (16-24 Hz) and sinusoidal rhythmic oscillations with a frequency of 8 Hz.

Rice. 121. EEG of young children (according to Dumermulh et a., 1965).
A - EEG of a child aged 6 days - low-amplitude asynchronous delta waves and single theta oscillations are recorded in all areas of the cortex - B - EEG of a child 3 years old - rhythmic activity with a frequency of 7 Hz is recorded in the posterior parts of the hemispheres - polymorphic delta waves are expressed diffusely - Frequent beta oscillations appear in the anterior regions.
In Fig. 121, B shows the EEG of a 3-year-old child. As can be seen in the figure, stable rhythmic activity with a frequency of 7 Hz is recorded in the posterior parts of the hemispheres. Polymorphic delta waves of different periods are expressed diffusely. In the frontal-central areas, low-voltage beta oscillations synchronized into the beta rhythm are constantly recorded.
At 4 years of age, in the occipital areas of the cortex, oscillations with a frequency of 8 Hz become more constant. However, theta waves dominate in the central regions (5-7 vibrations per second). Delta waves consistently appear in the anterior regions.
For the first time, a clearly defined alpha rhythm with a frequency of 8-10 Hz appears on the EEG of children aged 4 to 6 years. In 50% of children of this age, the alpha rhythm is consistently recorded in the occipital areas of the cortex. The EEG of the anterior sections is polymorphic. In the frontal areas there is a large number of high-amplitude slow waves. On the EEG of this age group, oscillations with a frequency of 4-7 Hz are most common.

Rice. 122. EEG of a 12 year old child. The alpha rhythm is recorded regularly (according to Dumermuth et al., 1965).
In some cases, the electrical activity of children 4-6 years old is polymorphic in nature. It is interesting to note that the EEG of children of this age can record groups of theta oscillations, sometimes generalized to all parts of the hemispheres.
By the age of 7-9, there is a decrease in the number of theta waves and an increase in the number of alpha oscillations. In 80% of children of this age, the alpha rhythm steadily dominates in the posterior parts of the hemispheres. In the central region, the alpha rhythm makes up 60% of all fluctuations. Low-voltage polyrhythmic activity is recorded in the anterior areas. The EEG of some children in these areas predominantly shows high-amplitude bilateral discharges of theta waves, periodically synchronized in all parts of the hemisphere. The predominance of theta waves in the parietal-central regions, along with the presence of paroxysmal bilateral bursts of theta activity in children aged 5 to 9 years, is assessed by a number of authors (D. A. Farber, 1969 - V. V. Alferova, 1967 - N. N. Zislina, 1968 - S. S. Mnukhnn and A. I. Stepanov, 1969, etc.) as an indicator of increased activity of diencephalic brain structures at this stage of ontogenesis.
A study of the electrical activity of the brain of children 10-12 years old showed that the alpha rhythm at this age becomes the dominant form of activity not only in the caudal, but also in the rostral parts of the brain. Its frequency increases to 9-12 Hz. At the same time, there is a significant decrease in theta oscillations, but they are still recorded in the anterior parts of the hemispheres, more often in the form of single theta waves.
In Fig. 122 shows the EEG of child A, 12 years old. It can be noted that the alpha rhythm is recorded regularly and appears with a gradient from the occipital to the frontal regions. In the alpha rhythm series, individual pointed alpha oscillations are observed. Single theta waves are recorded in the fronto-central leads. Delta activity is expressed diffusely and not roughly.
At the age of 13-18 years, the EEG shows a single dominant alpha rhythm in all parts of the hemispheres. Slow activity is almost absent; a characteristic feature of the EEG is an increase in the number of fast oscillations in the central areas of the cortex.
A comparison of the severity of various EEG rhythms in children and adolescents of different age groups showed that the most general trend in the development of electrical activity of the brain with age is a decrease, even complete disappearance, of non-rhythmic slow oscillations that dominate the EEG of children of younger age groups, and the replacement of this form of activity regularly pronounced alpha rhythm, which in 70% of cases is the main form of EEG activity of an adult healthy person.

Video: All-Ukrainian Association of Neurology and Reflexology

Electroencephalography or EEG is a highly informative study of the functional characteristics of the central nervous system. Through this diagnosis, possible disorders of the central nervous system and their causes are determined. EEG interpretation in children and adults provides a detailed picture of the state of the brain and the presence of abnormalities. Allows you to identify individual affected areas. Based on the results, the neurological or psychiatric nature of the pathologies is determined.

Prerogative aspects and disadvantages of the EEG method

Neurophysiologists and patients themselves prefer EEG diagnostics for several reasons:

• reliability of the results;
• no contraindications for medical reasons;
• the ability to perform research in a sleeping or even unconscious state of the patient;
• lack of gender and age boundaries for the procedure (EEG is performed on both newborns and elderly people);
• price and territorial accessibility (the examination is low cost and is carried out in almost every district hospital);
• insignificant time costs for conducting a conventional electroencephalogram;
• painlessness (during the procedure the child may be capricious, but not from pain, but from fear);
• harmlessness (electrodes attached to the head record the electrical activity of brain structures, but do not have any effect on the brain);
• the ability to conduct multiple examinations to track the dynamics of prescribed therapy;
• prompt interpretation of results for diagnosis.

In addition, no preliminary preparation is provided for conducting an EEG. The disadvantages of the method include possible distortion of indicators for the following reasons:

• unstable psycho-emotional state of the child at the time of the study;
• mobility (during the procedure it is necessary to keep the head and body static);
• the use of medications that affect the activity of the central nervous system;
• hungry state (a decrease in sugar levels due to hunger affects brain function);
• chronic diseases of the organs of vision.

In most cases, the listed reasons can be eliminated (conduct a study during sleep, stop taking medications, provide the child with a psychological mood). If the doctor has prescribed electroencephalography for your baby, the study cannot be ignored.

Diagnosis is not carried out for all children, but only according to indications

Indications for examination

Indications for functional diagnostics of a child’s nervous system can be of three types: control-therapeutic, confirming/refuting, symptomatic. The first include mandatory research after neurosurgical operations and control and preventive procedures for previously diagnosed epilepsy, cerebral hydrocele or autism. The second category is represented by medical assumptions about the presence of malignant neoplasms in the brain (EEG can detect an atypical lesion earlier than magnetic resonance imaging will show).

Alarming symptoms for which the procedure is prescribed:

• A child’s delay in speech development: impaired pronunciation due to a functional failure of the central nervous system (dysarthria), disorder, loss of speech activity due to organic damage to certain areas of the brain responsible for speech (aphasia), stuttering.
• Sudden, uncontrollable seizures in children (possibly epileptic seizures).
• Uncontrolled emptying of the bladder (enuresis).
• Excessive mobility and excitability of children (hyperactivity).
• Unconscious movement of the child during sleep (sleepwalking).
• Concussions, bruises and other head injuries.
• Systematic headaches, dizziness and fainting, of unknown origin.
• Involuntary muscle spasms at an accelerated pace (nervous tics).
• Inability to concentrate (distracted attention), decreased mental activity, memory impairment.
• Psycho-emotional disorders (unreasonable changes in mood, tendency to aggression, psychosis).

How to get correct results?

EEG of the brain in children of preschool and primary school age is most often carried out in the presence of parents (babies are held in their arms). No special training is required; parents should follow a few simple recommendations:

• Carefully examine the child's head. If there are minor scratches, wounds, scratches, inform your doctor. Electrodes are not attached to areas with damaged epidermis (skin).
• Feed the child. The study is carried out on a full stomach, so as not to blur the indicators. (Sweets containing chocolate, which excites the nervous system, should be excluded from the menu). As for infants, they must be fed immediately before the procedure in a medical facility. In this case, the baby will fall asleep peacefully and the study will be carried out during sleep.

It is more convenient for infants to conduct research during natural sleep

It is important to stop taking medications (if the baby is receiving treatment on an ongoing basis, you need to notify the doctor about this). Children of school and preschool age need to be explained what they have to do and why. The right psychological attitude will help you avoid excessive emotionality. You are allowed to take toys with you (excluding digital gadgets).

You should remove hairpins and bows from your head, and remove earrings from your ears. Girls should not wear their hair in braids. If the EEG is repeated, it is necessary to take the protocol of the previous study. Before the examination, the child's hair and scalp should be washed. One of the conditions is the good health of the little patient. If the child has a cold or other health problems, it is better to postpone the procedure until complete recovery.

Methodology

According to the method of implementation, the electroencephalogram is close to cardiac electrocardiography (ECG). In this case, 12 electrodes are also used, which are symmetrically placed on the head in certain areas. The application and attachment of sensors to the head is carried out in a strict order. The scalp in areas of contact with the electrodes is treated with gel. The installed sensors are fixed on top with a special medical cap.

Using clamps, the sensors are connected to an electroencephalograph - a device that records features of brain activity and reproduces the data on paper tape in the form of a graphic image. It is important that the little patient keeps his head upright throughout the entire examination. The time interval for the procedure, including mandatory testing, is about half an hour.

The ventilation test is carried out for children from 3 years of age. To control breathing, the child will be asked to inflate a balloon for 2-4 minutes. This testing is necessary to identify possible neoplasms and diagnose latent epilepsy. Deviations in the development of the speech apparatus and mental reactions will help identify light irritation. An in-depth version of the study is carried out on the principle of daily Holter monitoring in cardiology.

The cap with sensors does not cause pain or discomfort to the child

The baby wears the cap for 24 hours, and a small device located on the belt continuously records changes in the activity of the nervous system as a whole and individual brain structures. After a day, the device and cap are removed and the doctor analyzes the results. Such a study is of fundamental importance for identifying epilepsy in the initial period of its development, when symptoms do not yet appear often and clearly.

Decoding the results of the electroencephalogram

Only a highly qualified neurophysiologist or neuropathologist should decode the results obtained. It is quite difficult to determine deviations from the norm on a graph if they are not clearly defined. At the same time, standard indicators can be interpreted differently depending on the patient’s age category and health status at the time of the procedure.

It is almost impossible for a non-professional person to understand the indicators correctly. The process of deciphering the results may take several days due to the scale of the analyzed material. The doctor must evaluate the electrical activity of millions of neurons. The assessment of children's EEG is complicated by the fact that the nervous system is in a state of maturation and active growth.

The electroencephalograph records the main types of activity of the child’s brain, displaying them in the form of waves, which are assessed according to three parameters:

• Frequency of wave oscillations. The change in the state of waves over a second time interval (oscillations) is measured in Hz (hertz). In conclusion, the average indicator obtained by the average wave activity per second in several sections of the graph is recorded.
• The range of wave changes or amplitude. Reflects the distance between opposite peaks of wave activity. It is measured in µV (microvolts). The protocol describes the most characteristic (frequently occurring) indicators.
• Phase. This indicator (the number of phases per oscillation) determines the current state of the process or changes in its direction.

In addition, the rhythm of the heart and the symmetry of neutron activity in the hemispheres (right and left) are taken into account. The main assessment indicator of brain activity is the rhythm, which is generated and regulated by the most structurally complex part of the brain (thalamus). Rhythm is determined by the shape, amplitude, regularity and frequency of wave oscillations.

Types and norms of rhythms

Each of the rhythms is responsible for one or another brain activity. To decode the electroencephalogram, several types of rhythms are adopted, designated by the letters of the Greek alphabet:

• Alpha, Betta, Gamma, Kappa, Lambda, Mu - characteristic of an awake patient;
• Delta, Theta, Sigma - characteristic of the state of sleep or the presence of pathologies.

The results are interpreted by a qualified specialist.

Manifestation of the first type:

• α-rhythm. It has an amplitude standard of up to 100 μV, frequency - from 8 Hz to 13. It is responsible for the calm state of the patient’s brain, in which its highest amplitude indicators are noted. When visual perception or brain activity is activated, the alpha rhythm is partially or completely inhibited (blocked).
• β rhythm. The normal frequency of oscillations is from 13 Hz to 19, the amplitude is symmetrical in both hemispheres - from 3 μV to 5. The manifestation of changes is observed in a state of psycho-emotional arousal.
• γ rhythm. Normally, it has a low amplitude of up to 10 μV, the oscillation frequency varies from 120 Hz to 180. On the EEG it is detected with increased concentration and mental stress.
• κ-rhythm. Digital vibration indicators range from 8 Hz to 12.
• λ rhythm. It is included in the general functioning of the brain when visual concentration is necessary in the dark or with eyes closed. Stopping the gaze at a certain point blocks the λ rhythm. Has a frequency from 4 Hz to 5.
• μ-rhythm. It is characterized by the same interval as the α rhythm. It appears when mental activity is activated.

Manifestation of the second type:

• δ-rhythm. Normally recorded in a state of deep sleep or coma. Manifestation during wakefulness may indicate cancerous or degenerative changes in the area of ​​the brain from which the signal was received.
• τ-rhythm. It ranges from 4 Hz to 8. The startup process is carried out in a sleep state.
• Σ rhythm. The frequency ranges from 10 Hz to 16. It occurs during the stage of falling asleep.

The set of characteristics of all types of brain rhythmicity determines the bioelectrical activity of the brain (BEA). According to the standards, this evaluation parameter should be characterized as synchronous and rhythmic. Other options for describing BEA in a doctor’s report indicate disorders and pathologies.

Possible abnormalities on the electroencephalogram

Rhythm disturbances, the absence/presence of certain types of rhythm, asymmetry of the hemispheres indicate disruptions in brain processes and the presence of diseases. Asymmetry of 35% or more may be a sign of a cyst or tumor.

Electroencephalogram indicators for alpha rhythm and preliminary diagnoses

Beta rhythm parameters

Parameters of δ- and τ-rhythmicity

In addition to the described parameters, the age of the child being examined is taken into account. In infants up to six months of age, the quantitative indicator of theta oscillations continuously increases, and delta oscillations decrease. From the age of six months, these rhythms rapidly fade away, while alpha waves, on the contrary, are actively formed. Up until school, there is a stable replacement of theta and delta waves with β and α waves. During puberty, the activity of alpha rhythms prevails. The final formation of a set of wave parameters or BEA is completed by adulthood.

Failures of bioelectrical activity

Relatively stable bioelectroactivity with signs of paroxysm, regardless of the area of ​​the brain where it manifests itself, indicates the predominance of excitation over inhibition. This explains the presence of systematic headaches in neurological diseases (migraine). The combination of pathological bioelectrical activity and paroxysm is one of the signs of epilepsy.

Reduced BEA characterizes depressive states

Extra options

When decoding the results, any nuances are taken into account. The decoding of some of them is as follows. Signs of frequent irritation of brain structures indicate a disruption in the process of blood circulation in the brain, insufficient blood supply. Focal abnormal rhythm activity is a sign of predisposition to epilepsy and seizure syndrome. A discrepancy between neurophysiological maturity and the child’s age indicates developmental delay.

Violation of wave activity indicates a history of traumatic brain injury. The predominance of active discharges from any brain structure and their intensification during physical stress can cause serious disturbances in the functioning of the hearing aid, organs of vision, and provoke short-term loss of consciousness. In children with such manifestations, sports and other physical activities must be strictly controlled. A slow alpha rhythm can cause increased muscle tone.

The most common diagnoses based on EEG

Common diseases diagnosed by a neurologist in children after examination include:

• Brain tumors of various etiologies (origins). The cause of the pathology remains unclear.
• Traumatic brain injury.
• Simultaneous inflammation of the membranes of the brain and medulla (meningoencephalitis). The cause is most often an infection.
• Abnormal accumulation of fluid in brain structures (hydrocephalus or dropsy). The pathology is congenital. Most likely, the woman did not undergo mandatory screenings during the perinatal period. Or the anomaly developed as a result of an injury received by the baby during delivery.
• Chronic psychoneurological disease with characteristic seizures (epilepsy). Provoking factors are: heredity, trauma during childbirth, advanced infections, antisocial behavior of a woman during pregnancy (drug addiction, alcoholism).
• Hemorrhage into the brain substance due to rupture of blood vessels. It can be caused by high blood pressure, head injuries, or blockage of blood vessels by cholesterol growths (plaques).
• Cerebral palsy (CP). The development of the disease begins in the prenatal period under the influence of unfavorable factors (oxygen starvation, intrauterine infections, exposure to alcohol or pharmacological toxins) or head trauma during childbirth.
• Unconscious movements during sleep (sleepwalking, somnambulism). There is no exact explanation for the reason. Presumably, these could be genetic abnormalities or the influence of unfavorable natural factors (if the child was in an environmentally hazardous area).

For diagnosed epilepsy, EEG is performed regularly

Electroencephalography makes it possible to establish the focus and type of the disease. The following changes will be distinctive on the graph:

• acute-angled waves with sharp rise and fall;
• pronounced slow pointed waves combined with slow ones;
• a sharp increase in amplitude by several units of kmV.
• When testing for hyperventilation, narrowing and spasms of blood vessels are recorded.
• during photostimulation, unusual reactions to the test appear.

If epilepsy is suspected and during a control study of the dynamics of the disease, testing is carried out in a gentle manner, since stress can cause an epileptic seizure.

Traumatic brain injury

Changes to the chart depend on the severity of the injury. The stronger the blow, the brighter the manifestations will be. The asymmetry of the rhythms indicates an uncomplicated injury (mild concussion). Uncharacteristic δ-waves, accompanied by bright flashes of δ- and τ-rhythmicity and unbalanced α-rhythmicity may be a sign of bleeding between the meninges and the brain.

An area of ​​the brain damaged due to injury always exhibits increased activity of a pathological nature. If the symptoms of a concussion disappear (nausea, vomiting, severe headaches), abnormalities will still be recorded on the EEG. If, on the contrary, the symptoms and electroencephalogram indicators worsen, a possible diagnosis would be extensive brain damage.

Based on the results, the doctor may recommend or oblige you to undergo additional diagnostic procedures. If it is necessary to examine in detail the brain tissue, and not its functional features, magnetic resonance imaging (MRI) is prescribed. If a tumor process is detected, you should consult a computed tomography (CT) scan. The final diagnosis is made by a neurologist, summing up the data reflected in the clinical electroencephalographic report and the patient’s symptoms.