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Electroencephalography is one of the basic tests to assess brain function. EEG performance is recommended in special cases. We check when to come for the test and how it is going, as well as what the preparations for the EEG look like.
EEG test – what is it?
The EGG test consists in checking the bioelectrical activity of the brain, which is possible thanks to electrodes attached to the scalp on a special electroencephalograph. The device looks like a cap / net to which colored electrodes are attached. The recorded signal is generated by impulses transmitted between neurons.
Indications for an EEG
Head EEG is performed in very specific cases. First of all, they are used in the diagnosis of epilepsy. Thanks to the examination, it is possible to check which forms of treatment will be the most appropriate. In addition, it is also extremely helpful in indicating the causes of sleep disorders (it allows you to determine what type of coma the patient is in). Sometimes the EEG is useful in assessing the state of the brain after poisoning with neurotoxic agents. The attending physician may order an EEG of the head after various types of trauma.
The indications for the performance of the EEG are also changes that are grounded in the nervous system. This is especially about unexplained fainting, fainting, loss of balance or symptoms affecting the sensory organs, e.g. visual or hearing impairment. EEG testing is also ordered in case of frequent headaches. Electroencephalography of the head can also detect the causes of stuttering in some cases.
See what reasons your child may be stuttering for
Preparation for the EEG test
EEG testing does not require any special preparation from the patient. However, it is worth remembering that 48 hours before the scheduled visit, stop taking all substances that could in any way affect the brain’s functioning. It is mainly about drugs affecting the nervous system, because they can disturb the EEG result the most. You should also give up coffee and alcohol.
On the day of the examination, first of all, you need to eat an easily digestible meal. This is important as changes in glucose levels can affect brain activity.
It is also important to wash your scalp hair thoroughly and not to apply any styling products to it as this could interfere with neuronal conductivity.
EEG progression of the head
Electroencephalography is painless, so don’t be alarmed. The doctor carrying out the examination will apply a gel in the appropriate places on the head, which allows for better signal transmission to the electrodes. Then a cap with electrodes is put on the head. The patient lies down. Lying down, she will spend the next several dozen minutes.
During the test, tests are performed with closing and opening the eyes, photostimulation and hyperventilation, but most of the time the subject lies still with his eyes closed.
The head EEG lasts 45 minutes.
Interpretation of EEG results – alpha, beta, theta, gamma waves
When interpreting the EEG results, the amplitude and frequency of the brain waves are analyzed. There are several basic waves that can appear naturally in the EEG recording:
• Alpha waves (frequency 8-13 Hz, amplitude 30-100 mcV / m) – recorded when the subject is resting with his eyes closed. However, when visual stimuli appear, they are suppressed;
• Beta waves (frequency 12-30 Hz, amplitude> 30 mcV / m) – are characteristic of the state of focused attention;
• Gamma waves (frequency 25-100 Hz) – appear during the perception of sensory stimuli and during remembering.
• Delta waves (frequency 1-3 Hz) – are associated with sleep;
• theta waves (frequency 3,5-8 Hz) – associated with hypnosis, but also with memory processes. They register all kinds of emotional disturbances.
With non-physiological brain activity, the amplitude and / or frequency of the brain waves is disturbed, which can be seen in the EEG record. In the correct result of electroencephalography alpha waves appear at the parietal and occipital lobes, as well as beta waves present at the front lobes. In rare cases, theta waves may also occur.
An abnormal EEG result assumes the appearance of pathological waves (including tetha)which should not appear at the moment. However, the research cannot be interpreted on its own, as not all anomalies indicate disorders.
EEG testing in children – can it be performed?
Head EEG can also be performed on children. In some cases, babies are ordered to undergo testing. In this case, during the measurements, there may be a parent in the room, who will hug the baby lying on the bed. If a child has difficulty holding a position for a long time, caregivers should raise the issue prior to the examination.
EEG test – how much does it cost?
Head EEG can be performed under the National Health Fund. You will only need a referral from a neurologist. If we want to perform the test privately, its cost will be about PLN 100.