In what cases can be assigned an brain encephalogram: indications and description of the diagnostic method



Under the complex name lies a safe, easy-to-conduct method for studying the brain that captures electrical impulses and fixes their rhythm and frequency. The electroencephalogram of the brain provides information about the functional characteristics of this organ.

EEG is a study that can be performed on patients of different ages in any condition. Electroencephalograph, a device for the study, is indispensable in the intensive care wards. It is his connection to patients in a coma to track the slightest changes in the electrical activity of the brain.

Electroencephalography can be conducted in parallel with the patient’s exposure to irritating factors: sounds, light, sleep deprivation. So get a clearer picture of the nature of the violation, areas of epileptic activity.


After the EEG, it is more likely to exclude or confirm the presence of such pathologies in a person as:

  • vascular dystonia;
  • brain inflammations;
  • neoplasms;
  • epilepsy;
  • hypertonic disease;
  • nervous disorders;
  • osteochondrosis of the cervical spine;
  • vascular disorders;
  • traumatic brain injury.

The electroencephalogram of the brain displays the state of the organ in the postoperative period, after a stroke, the dynamics of changes after the treatment. It is necessary when passing the medical commission to get a driver’s category C and D.

How to prepare

To pass the survey you need to prepare. Tell your doctor about taking certain medications. Some of them affect brain activity and should be canceled 3-4 days before the examination. Such drugs include anticonvulsants, tranquilizers.

On the eve of the EEG and on the day of the meeting, caffeinated products and energy products should not be consumed: coffee, tea, chocolate, energy drinks. Do not drink . These products have a stimulating effect on the brain, and the brain’s brain encephalogram will be distorted.

A few hours before the examination, it is desirable to eat.

It is recommended to wash your hair, but not apply varnish, styling foam, other cosmetics. The fats and other components contained in them can worsen the contact of the electrodes with the scalp. Braids, dreadlocks will have to stitch, and earrings, jewelry removed.

During the procedure you need to stay calm and not be nervous. Nothing terrible happens, and the procedure is completely harmless.

EEG conduction

Usually, electroencephalography is performed in a specially equipped room, protected from noise and bright light, in which there is a stationary electroencephalograph. If necessary, conduct mobile EEGs on the road.

The patient is offered to lie down on a couch or sit comfortably in a chair. A helmet or cap with electrodes is put on the head, the number of which depends on the patient’s age. A small child needs 12 electrodes, 21 are used for adults. The electrode cavity is filled with a special substance that facilitates the rapid transmission of electrical impulses. Signals from the area near the electrode have the greatest clarity and power. Signals received from remote sites are weak.

The cap connects with the encephalograph, which is able to pick up the oscillation frequency of 0.5-100 Hz and performs the function of an amplifier. The electrical signal is amplified by the encephalograph millions of times and transmitted to the computer for further processing. Here, a huge number of signals is converted into a graph – an encephalogram, which the doctor analyzes.

The patient during the study should be calm, do not move. Only at the very beginning can the doctor ask him to blink several times in order to assess the nature of technical errors. If the patient needs to urgently change the position of the body or go to the toilet, the study is stopped. In a situation when he made an involuntary movement, he moved, the doctor makes a corresponding note so that with further analysis false information will not appear.

Brain encephalogram is recorded for about 15-20 minutes.

EEG with provocative tests

If necessary, after the main entry make provocative tests:

  1. With hyperventilation – the patient is asked to breathe deeply for a few minutes.
  2. Test with a bright light. It uses a special device capable of reproducing repetitive light pulses. An electroencephalogram of the brain captures the response of the patient.
  3. Trial with an unexpected sound.

Samples help to find out the real cause of the violation – it is a manifestation of the pathological process, mental impairment or simulation. In the presence of a valid pathology, conducting tests may trigger an epileptic seizure or convulsions. Therefore, the physician performing the diagnosis has the experience and knowledge necessary to provide emergency care. The time of the procedure with samples increases.

EEG with sleep deprivation

If there is suspicion that the usual EEG did not give complete and reliable information, electroencephalography is prescribed with sleep deprivation. Some sources indicate that only in 20-30% of cases with a standard encephalogram of the head showing signs of epilepsy. Data obtained during sleep is considered more accurate. Before conducting a study, an adult should not sleep for 18 hours. In some cases, if the examination is carried out in a hospital, the patient is awakened in the middle of the night and forced to undergo a diagnosis.

If the patient was able to quickly fall asleep, the procedure takes about an hour. The doctor or nurse makes notes regarding any changes to the patient: jerks, eye, arm, leg movements. In the future, the brain encephalogram will be interpreted with their help.

At the end of the procedure, the patient is awakened, checked for his condition and sent home or to the ward. After the diagnosis is recommended rest.

Features of the EEG in children

It is not easy for a small child to have an EEG of the brain. He is frightened by a large number of wires, a strange cap, unfamiliar surroundings, people, appliances. It’s hard enough to convince the kid that for some time he will have to lie still. Young are examined during sleep. Before the study, they need to limit the rest time, so that he is tired and wanted to sleep. On the day of the examination, babies are woken up 4-6 hours before the usual rise time. Children of primary school age – for 6-8 hours, and children over 12 years old are not allowed to fall asleep at night.

You can wear a hat by inventing stories about knights rushing to a campaign with monsters. You can practice in advance, wearing a swimming cap or real helmets.

Be sure to wash before the procedure – wash your hair. Girls do hair with her hair – let him imagine that today she is a mysterious princess, waiting for a brave knight to save her from the clutches of a monstrous dragon.

A couple of hours before the study of the child to feed, and leaving the house, do not forget to bring a toy, a book or treats, so that there is something to do while waiting.

EEG children can spend at home, in a hospital or clinic. The best way is to spend it at home in the evening before bedtime – at 8-9 o’clock in the evening. The familiar atmosphere will calm the baby and will provide more accurate results.

When conducting a survey, a close relative should be with the child – a mom, dad or grandmother.

Electroencephalogram is shown in a child in the following situations:

  1. Seizures appear at high temperatures.
  2. There was an incident with an epileptic seizure.
  3. Ischemic damage to the central is suspected.
  4. It is necessary to evaluate the correctness of the formation of bioelectric activity.
  5. With a confirmed pathology of the brain, it is necessary to make a forecast of the development of the lesion and evaluate its dynamics.


Normally, nerve impulses emanating from different parts of the brain are consistent, harmoniously weaken or reinforce each other under the influence of their other factors. These features, as well as violations, can be seen in deciphering the EEG of the brain.

The main indicators that gives the study:

  1. Frequency – the indicator reflects the number of waves in a certain period of time. It is expressed in hertz. The description includes the average frequency, analyzing several parts of the record.
  2. For information about the amplitude, measure the distance between the peaks in opposite phases. In conclusion, only the most frequent values ​​are described. It is expressed in microvolts.
  3. Phase – estimated the current state and its changes.
  4. Rhythm is a type of electrical activity. The description indicates the frequency, amplitude, changes.

In spite of the fact that in an adult with EEG 9 rhythms are recorded, 4 are important for analysis.

In what cases can be assigned an brain encephalogram: indications and description of the diagnostic method
RhythmNormDeviationPossible pathology in adultsPossible pathology in children
Alpha rhythm8-13 Hz, uniform frequency, amplitude – up to 100 µV.

Maximum concentration in the region of the vertex, the back of the skull

Hemispheric asymmetry

Tumor, cyst, stroke, scar after stroke, hypertension, epilepsyDelayed psychomotor development, neurosis, psychopathy
Paroxysmal rhythmNeurosis
Frequency violation

Absence or disorganization of rhythmDementia
Appearance in the frontal areaPsychopathology
Beta rhythm13-30 Hz, amplitude – 3-kmkV, frontal lobesFrequency violationMigraine, hypertension, circulatory disordersNeurosis
Amplitude increaseConcussionPsychopathology
Hemispheric asymmetryInflammatory diseasesDevelopmental delay
Paroxysmal rhythms
Delta rhythm4-7 Hz, amplitude – 25-35 µVHigh amplitudeStroke, Alzheimer’s disease, post infarction dementiaHigh rates may indicate developmental delay, impaired blood circulation
Low frequency
Appearance in wakefulness
Theta rhythm0.5-3 Hz, the amplitude is not higher than 40 mVV, reflects the state of sleep of an adult, dominates in childrenHigh frequencySevere CNS pathologies, injuries

High amplitudeNeoplasm,

Alzheimer’s disease

Only a doctor can decipher the EEG data correctly, taking into account the totality of the data and the history of the disease.


Electroencephalography has no contraindications, but in young children it is better to spend it in a dream. With the exacerbation of you need to wait for the normalization of the state. The study is conducted with caution in people with injuries and head injuries.

Electroencephalography is a safe informative research method that allows you to reliably diagnose certain diseases of the brain. EEG of the brain shows that it is the basis of loss of consciousness, fatigue, insomnia, headaches. It is used in children and adults in any condition.

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