EEG in epilepsy. What should you know
What is an EEG of the brain? How is it carried out in children and adults? What does the electroencephalogram show in epilepsy and what does the decoding say?
- An electroencephalogram is the most important test for suspected epilepsy in a child or adult, which checks for the presence of epileptic brain activity, but does not confirm or refute the diagnosis.
- Pathological activity can be registered even in perfectly healthy people.
- In most cases, one or two studies are enough – there is no point in tracking the dynamics.
What is an EEG of the brain
An EEG study is carried out in order to detect epileptic activity, determine its form, frequency and localization. The results of the test allow specialists to determine the type of epilepsy and prescribe the appropriate treatment for the child or adult.
An EEG (electroencephalogram) is a test that records electrical brain waves using electrodes attached to the skull. With epilepsy, the patient exhibits characteristic changes – epileptiform activity.
Types of electroencephalogram
There are several types of EEG, which are assigned as needed, in each case:
- EEG in wakefulness. The study in this case is carried out in a stationary state, since movements can create interference that will complicate decoding.
- EEG in sleep. This check is necessary in cases where a child or adult has seizures during night or daytime sleep.
- Video-EEG monitoring. The check is carried out when there is a need to confirm that the epileptic activity that is recorded on the electroencephalogram is accompanied by certain external manifestations. Video-EEG monitoring is usually done in children and adults with drug resistant epilepsy who are recommended for surgery.
During the test, the patient undergoes a series of stimulations that, in some cases, help induce epileptic activity. Stimulations can be in the form of photostimulation (bright flashing light) or hyperventilation (intense breathing that exceeds the body’s need for oxygen).
In some cases, during the EEG, stimulation data helps to determine the trigger (cause) that can cause an attack in a particular patient.
Deciphering the EEG and what the results mean
Some patients wonder: how to get a good EEG result? The answer to this question is extremely simple – it is impossible to influence the results of the study in any way (except for taking drugs).
The diagnostic assessment takes into account the frequency composition of the electroencephalogram, its components and the nature of the organization (pattern) of bioelectric activity.
Deciphering the EEG, in epilepsy and other conditions, consists of several parts: introductory, descriptive and interpretation.
The first part (introductory) describes the state of the patient, what drugs he took and other points related to his condition at the time of the tests.
The second part (descriptive) includes all types of activity that were recorded on the EEG of the brain. This describes both normal and abnormal characteristics, as well as the most pronounced components. The second part includes a complete and objective report on the results of the examination.
The third part (interpretation) represents the conclusions that were made during the survey and based on its results described in the first and second parts. Some mistakenly believe that an encephalogram diagnoses epilepsy. However, in many cases it is impossible to make an accurate diagnosis and prescribe treatment only on the basis of an EEG.
How an EEG is performed for children and how to prepare for it
An EEG for children can be prescribed by a pediatrician, a neurologist, or an epileptologist. In this case, the study is assigned to both newborns and older children.
The very process of conducting an EEG of the brain is absolutely safe, non-invasive and painless. The electrodes are attached to the patient’s head using a small disc and a specialized gel that is easily washed off after the procedure while washing the head.
In the evening before the test, it is recommended to wash the child’s head.
In some centers, the study is carried out using a cap (a specialized helmet with built-in electrodes), but in Israel this method is rarely used. This is due to the fact that when conducting an EEG in a cap, the electrodes can move and do not fit snugly to the head, which can distort the test result. In Israel, electrodes are attached to the head by specialists by hand, which helps to obtain accurate results of the study.
During the electroencephalogram, the child will be asked to open and close his eyes, breathe deeply and often, clench and unclench his fists, etc. Methods of influence are selected depending on each specific case, but the child must be prepared in advance for the study. For young children, this study can be presented as an exciting game, so that the child can easily endure the study and not be afraid. During the check, parents can be near the baby to make him feel more comfortable.
EEG with sleep deprivation
An EEG with lack of sleep (deprivation) is performed if a child or adult has seizures during sleep. To undergo such an examination, the patient must be awake the night before the procedure. The time of deprivation itself depends on the age of the patient and is set by the doctor.
If it is necessary to conduct this study in children, parents should walk and entertain the child during the night so that the child falls asleep during the procedure and it is possible to check for the presence of epileptic activity during sleep.
Many parents of young patients fear that the child will not be able to sleep, but, as practice shows, this rarely happens.
How long does the check take
As a rule, a typical electroencephalogram lasts from 20 to 45 minutes. However, in some cases, the study time may be increased.
Video-EEG monitoring can be carried out for a day, several days or even weeks until enough information is received to make a decision on further actions.
Does an EEG always show epilepsy?
It is important to remember that EEG does not confirm or disprove epilepsy. The epileptic activity of the brain, which is recorded on the EEG, gives doctors information about a specific type of epilepsy, and from this follow decisions about the necessary additional tests and treatment.
It is quite possible that a child or an adult has epileptic seizures, but the EEG does not show epilepsy (epileptic activity), even if the study is repeated many times.
There are also reverse situations, when the conclusion of the EEG of a healthy person who does not experience epileptic seizures contains epileptic activity. According to statistics, in about 2% of completely healthy people, epileptic activity will be noticed during an EEG.
Despite the fact that the EEG is not a diagnostic test, its results are extremely important in order to understand the type of disease in a particular patient and prescribe the appropriate treatment for him.
Additional checks for suspected epilepsy
In order to make an accurate diagnosis and recommend the necessary treatment, in addition to the clinical description of seizures and an electroencephalogram, it is also important to conduct blood tests and MRI of the brain (not in all cases of the disease this is necessary).
How often can and should an EEG be done?
The check is absolutely harmless, but it makes no sense to repeat it without a reason.
Periodic electroencephalogram may be required in case of electrical status epilepticus in slow -wave sleep (ESES). In other cases, it is enough to conduct one or two EEGs in order to determine the pathology.
Some patients are prescribed a second study after reaching the recommended daily dosage of drugs. A repeated EEG of the brain is also necessary if the seizures have changed or if they have been absent in the patient for more than 2 years. In this case, if the EEG is normal, the question of canceling drug treatment may be raised.
The decision to stop taking antiepileptic drugs is made by the attending physician, since not in all cases it is possible to cancel drug treatment, even in the absence of seizures or epileptic activity on the EEG.