Eeg (electroencephalography): definition, function and examination

Understanding EEG

What is electroencephalography (EEG)?

Electroencephalography / electroencephalogram or electroencephalography (EEG) is a test to measure electrical activity in the brain, using a small metal disk-shaped device (electrodes) attached to your scalp. This test can identify abnormal electrical activity in your brain, which may indicate a nervous system disorder or certain brain disease in you.

For information, your brain cells communicate through electrical impulses that are active all the time, including during sleep. During an EEG examination, the electrical activity will be recorded in the form of wavy lines on a computer screen, which can be printed on paper for easier reading and interpretation.

An EEG examination is a test usually performed by a trained specialist, which is called clinical neurophysiology. This test is generally done during a visit or examination to a hospital or laboratory.

EEG function

The main function electroencephalography (EEG) is to detect and investigate epilepsy, which is a condition that causes a person to experience recurring or recurring seizures. With this brain record test, your doctor can identify the type of epilepsy you have, the things that might trigger recurrent seizures, and the right and best treatment. However, an EEG can also be done for several other conditions.

Conditions That Can Benefit From an EEG Examination

However, electroencephalography can also be used to help detect and investigate other brain disorders, such as brain tumors, strokes, dementia (including Alzheimer's disease), inflammation of the brain (encephalitis), and brain injury.

In addition, EEG examinations are also commonly performed in other conditions with specific purposes, such as:

• Confirms brain death in someone who is in a coma.
• Helps find the proper level of anesthesia in a person who is in a medically induced coma.
• Identifying sleep disturbances or behavior changes.
• Monitor brain conditions, including blood flow to the brain, during surgical procedures.
• Find out the cause of fainting or unexplained periods of memory loss.
• Evaluate brain activity after a severe head injury, or before a heart transplant or liver transplant.

Apart from the ones mentioned above, there may be other reasons for your doctor to recommend an EEG exam. However, this test cannot be used to measure a person's intelligence. Consult with your doctor about medical examination tests that are right for your condition.

Before the EEG

Before undergoing the electroencephalography test, the medical team will tell you what to do and be prepared. However, in general, some of the preparatory steps you need to take before undergoing an EEG examination are:

• Wash your hair or shampoo, but not with conditioner, the night before the test.
• Do not use hair products, such as gels or hairspray, after shampooing and before the test is done.
• Tell your doctor and medical team about any medications and supplements you are taking, including herbs.
• Your doctor may ask you to stop taking some medications that will interfere with the test. However, do not stop taking these drugs without first consulting your doctor or medical team.
• Avoid consuming foods or drinks that contain caffeine in the 8-12 hours before the test.
• Avoid fasting the night before the exam or on the day the test is run. Low blood sugar due to fasting can affect your EEG results.

Matters that need to be considered during the EEG examination

You may need to sleep while the test is running. Therefore, you may be asked to cut back on sleep the night before. If the EEG is done asleep, adults may be advised not to sleep more than 4-5 hours, while children may not sleep more than 5-7 hours the night before the test.

For EEG examinations in children, the doctor may provide suggestions or other ways to help the child fall asleep more easily while the test is run.

In addition to preparing for the above, you may need to take the comb to the hospital when the test is run. The reason is, your hair may be a little messy once the test is over. However, some people may prefer to bring a hat or other covering to cover their hair after the examination.

During the EEG

Examination electroencephalography generally runs for 20-40 minutes or even an hour. This includes time to consult with the medical team and prepare equipment at the start and end of the test. As for electroencephalography during sleep, it generally takes a longer time.

In addition, some electroencephalographic examinations can also be carried out continuously or EEG monitoring for up to 24 hours. This condition usually allows you to be hospitalized or have an outpatient electroencephalography examination for several days.

EEG procedure steps

During this EEG test, you may be asked to sit back in a chair or lie down on a bed. Then, a technician will measure your head and mark your scalp with a special pen to mark the place where the electrodes will be attached.

After that, about 16-25 electrodes will be attached with glue or special paste to the marked points on your scalp. Sometimes, however, you may just need to use a special elastic cap or head covering already equipped with electrodes.

These electrodes are connected by cable to an electroencephalography recording machine. The way this EEG device works is by sending your brain waves, the results of which will be recorded on computer equipment.

Once the exam is started, you should be in a relaxed and comfortable position with your eyes closed. However, at certain times, the technician may ask you to open and close your eyes, do some simple calculations, read certain sentences, look at a picture, take a deep breath, or see flashing lights.

Every time you do these things, your body movements will be recorded by a video camera and an EEG will record your brain waves. The recording may also be stopped periodically to let you rest or change positions.

After the EEG

After the test is complete and the medical team has got the results of the brain record, the electrodes will be removed from your head. In some cases, you may need to wash your hair again when you get home because of the glue, but in others you may not.

Also, at the point where the electrodes are attached, there may be redness or skin irritation. Don't worry though, this is normal and should usually go away within a few hours. Consult your doctor or medical team if the condition is quite bothersome.

Care should be taken for patients who are taking sedatives during the EEG examination

Meanwhile, under certain conditions, the patient may need to take sedatives during the EEG examination. If you are one of them, you may be asked to rest after the test until the sedative effect wears off.

In this case, you may need someone to drive you home. Once you get home, rest and don't drive for the rest of the day.

However, if you are not taking sedatives, you should not experience any side effects after the procedure. You too can return to your normal routine.

Before returning from the examination site, make sure the medical team or doctor has told you when you can continue taking the medicine that was temporarily stopped before the test. In addition, doctors and the medical team may give additional instructions according to the condition of each patient.

How to read EEG results

Generally, you will not get your brain record results on the same day that the test is done. The reason is, the record needs to be analyzed first by a clinical neurophysiologist and will be sent to a doctor who requests an electroencephalogram test to be done. You will not be able to discuss the results with your doctor in the next few days or weeks.

Normal EEG Results

During the discussion or appointment, the doctor will interpret the results electroencephalography that you live. A normal EEG result generally shows a normal wave line pattern as well.

Reporting from MedlinePlus, the brain's electrical activity has a number of waves per second (frequency) which is normal for various situations. For example, brain waves are faster when you wake up and slower at certain stages of sleep.

Abnormal EEG Results

On the other hand, an EEG result with an abnormal pattern usually indicates the presence of certain medical conditions or disorders, such as seizure disorders (epilepsy), sleep disturbances, brain injury, migraine, swelling of the brain (edema), abnormal bleeding (hemorrhage), abnormal structures in the brain. (tumor), or tissue death due to blockage of blood flow in the brain (cerebral infarction / stroke infarction).

Other medical conditions may reflect the results of the electroencephalogram. Consult with your doctor about the results of the test that you are undergoing.

EEG side effects

Electroencephalography has been used for years in the medical world and is considered a safe procedure. This test does not cause any pain or sensation in the patient. Even the electrodes that record electrical activity in the brain do not pose a risk of electric shock.

Generally, you will only feel tired and have messy hair after the test. In some cases, you may feel dizzy and tingling in the lips and fingers when the test is done.

Additionally, some people may experience a rash, redness, or irritation of the skin where the electrodes were placed. However, this generally only happens temporarily and can go away within a few hours.

In certain cases, a person may experience seizures during the EEG procedure. This condition usually occurs in someone with a seizure disorder who may be deliberately triggered by the medical team to record your brain activity during the seizure.

However, these seizures can also be caused by flashing lights or a change in breathing pattern that may have occurred during the test. If this happens to you, the medical team will immediately provide the appropriate treatment if needed.

Other risks or side effects may occur in someone with certain medical conditions. Therefore, make sure to always consult a doctor before running the test, including if you have certain medical conditions that need attention.