Electroencephalography (EEG) process

The process of electroencephalography (EEG)

The method of electroencephalography

EEG analyzes the brain waves or electrical activity by stimulating with vision, hearing or other irritants. Basic waveforms are alpha, beta, delta and theta waves. During the examination, electrodes consisting of small metal discs with thin wires are attached to the patient’s head. Electrodes record the electrical potential produced by the brain cell activity. Results of investigations are displayed on the computer screen in the graph or as a record. After examination, the doctor interprets electroencephalogram records.

Need for examination

Electroencephalography (EEG) is used to assess the impairment of brain function in cases of following diseases:
• Epilepsy;
• Attacks of unconsciousness;
• Impairment of brain function after a stroke;
• Damage or a tumor;
• To diagnose other diseases affecting the brain, such as Alzheimer’s disease;
• Behavioral and sleep disturbances.

Possible side effects

Electroencephalography (EEG) has been used for many years, and it is considered a safe procedure. This examination does not cause any discomfort. The electrodes only record the brain’s electrical activity without any subjective discomfort. In rare cases patients may experience cramps caused by visual or hearing irrtants applied during EEG. Other risks may be associated with the patient’s general state of health or other diseases, therefore it is recommended to discuss unclear items with your doctor in a prior.

Certain factors or conditions that may affect the results of the examination:

• low blood sugar (hypoglycemia), which may lead to examination on an empty stomach;
• eye movement during the test;
• separate medicaments such as sedatives;
• beverages containing caffeine, for example, coffee, cola, tea (these drinks may occasionally change the EEG results, but they almost never interfere with the interpretation of the test);
• hair spray or hair oil presence.

Preparation for examination

Your doctor will explain the nature of the examination process and you will be able to clarify outstanding issues, if any will incur. You can wash your hair with shampoo on the previous evening, but do not use conditioner. Do not use the following hair care products: hair spray, oils or gels. Tell your doctor about all medications and supplements that you are taking.  Avoid caffeine-containing products 8-12 hours before the examination as well as fasting on the day of examination or night before, because low blood sugar may influence the results. Based on your general health state, your doctor may recommend another special preparation.

During the examination

Typically, electroencephalography (EEG) examination takes place as follows:
• You will be asked to sign a consent form for the examination. Read the form carefully and ask questions if there are any outstanding issues.
• You will be asked to take a seat and relax in the examination chair.
• Electrodes will be attached to your head.
• After initial registration an additional testing will be carried out by different promoters, for example, you may be asked to breathe deeply and rapidly for three minutes or perform the visual stimulation with bright light.

A doctor or nurse usually carries out EEG and its duration is approximately 45 minutes.

After the examination

Once the examination is complete, the electrodes will be removed from your head. In some cases, hair can be moistened. The doctor will inform you about further using of your medications, if you have stopped to use them before the test. After the procedure, the doctor will give you additional instructions based on your examination results.

Online resources

The above text is the reference to other websites (American Academy of Neurology, Brain Injury Association of America, Epilepsy Foundation, National Institutes of Health, National Library of Medicine), which contains information about the EEG procedure and related health conditions. We hope that this information will be useful for you. However, we do not control or endorse the information provided in these websites.

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