EEG Primer – Part 3

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EEG is not so simple to setup


The EEG test is completely safe and painless. The patient does not feel any sort of discomfort and there are no risks associated with an EEG.

Some EEG’s do not have any stimuli which may be useful in detecting abnormalities. Stimuli like flashing light may be added so that abnormalities become apparent.

If the patient is suffering from epilepsy or has some other sort of seizure disorder, the stimuli presented, such as a flashing light or some sort of sound, may result in a seizure. The technician must be trained to manage such situations before performing the EEG.


Following steps must be taken to ensure that EEG gives accurate results

  1. Make sure that you hair is clean on the day the EEG is performed. There is no product in your hair like sprays or gels.
  2. In case your doctor has advised not to take any prescribed medicine before the test, make sure that you haven’t. Also, a list of medications that your take should be given to the technician as well that is performing the test.
  3. Do not eat and drink food that contains caffeine for a minimum of 8 hours prior to the test.
  4. As you might have to sleep and relax during the test, the doctor will advise you to sleep as little as possible before the night of the test. During the test you might also be given sedatives so that you relax.
  5. After the test is over, you can carry on with your regular routine. If a sedative was given to you in might take a while for it to get out of your system. So you will have to bring someone along who will take you home after the procedure. Make sure you rest till the effect of the medication wears off.


The test only takes about 30-60 minutes. The procedure starts with you lying on the table or the bed, the technician will mark the places where the electrodes will be placed, the area will be scrubbed with a special liquid so that high quality recording is done. 20 small sensors are attached to your scalp by the technician. Brain activity is picked up by these sensors also known as electrodes, and is then sent to the machine by the neurons. They are either displayed on the monitor screen of the computer or are recorded as patterns of lines on moving paper. The electrical activity passing between your skin and the electrodes is very low, so your skin will not feel any sort of discomfort.

The technician will ask you to relax with your eyes open at first, and closed after. You will have to breathe deeply and might have to react to a stimulus, for example a flashing light; this will result in a different brain pattern. He might ask you to close or open your eyes or look at specific thing, like an object or a picture. All of this will produce different patterns, It is rare to have a seizure during the test but people suffering from epilepsy might have one when reacting to the stimulus, but the chances of this happening are low.

A test called polysomnography will be done if you are sleeping during the test; this is done to check bodily functions like the pulse or your breathing.

For capturing seizure activity of patient suffering from epilepsy, the patient might undergo a test of 24 hours. The EEG uses video for recording seizure activity. Any abnormalities that didn’t occur during the test become apparent during the EEG. These abnormalities are limited to seizure-related.


After the test is performed, the electrodes will be removed by the technician. Any residue left from the glue that was holding the electrodes in place can be removed by a nail polish remover at home. It is advised to have someone along when going for an EEG test as you might be given sedatives or if a patient is actively suffering from seizures, so that they can accompany you home. The prescribed medications which were stopped by the doctor before the test can be started to be taken again. The doctor, neurologist will look at the recordings of the brain activity. He will inform if there is any unusual activity that might suggest a problem with your brain. He may schedule an appointment to go over the results. If the brain activity is normal then it means you have no brain disorder.

It is advised to discuss the results of the test with your neurologist. You should also write down any questions that you have in mind prior to the reviewing of the test. Make sure that you speak up and get the doctor to ask any queries regarding your results that you might be having difficulty understanding. Don’t leave any doubt.