 Electroencephalogram (EEG)
An electroencephalogram is a non-invasive, diagnostic test which records electrical activity on the surface of the brain, and can identify the location of the abnormally firing neurons. An electroencephalograph is the instrument used to register this activity and record it on graph paper. This is used by a neurologist to help identify the location, severity, and type of seizure disorder. This safe and painless procedure will not affect you in any way.
Electro refers to electricity;
encephalo refers to the brain;
gram refers to record.
An EEG test may be administered to determine whether there are any irregularities electrical activities occurring in the brain which may produce seizures. This may help the doctor to determine whether you have epilepsy and in what form.
It is important to remember that an abnormal EEG does not diagnose epilepsy nor does a normal EEG reading exclude epilepsy.
An EEG can only measure abnormal electrical activity that occurs during the test period. Sometimes, the brain of the person with epilepsy functions perfectly normal during the test.
Tests that have been done on people with epilepsy commonly show uneven activity or large changes in the voltage of brain waves (spikes). Different patterns of activity from different spots on the scalp point to different kinds of epilepsy.
Before an EEG
- If the doctor has ordered a sleep test, adjust your sleeping schedule (reduce sleep) according to the doctor's instructions and avoid caffeine drinks.
- Wash your hair thoroughly. Your scalp should be clean and oil-free for the test so that electrodes can stay on your head and work effectively. No conditioners or any hair products should be used.
- Remove any hair accessories before going to the test centre.
- It is important to eat before being tested in order to help stabilize your blood sugar level.
- Continue to take your medication(s) unless instructed otherwise by your doctor.
During an EEG
- Before the test, you may be asked to provide information about your medical history and any medications being taken.
- The test may be given in a small room separated from the EEG machine and the technologist. This allows you to take the test in a quiet, relaxing environment.
- Some clinics may have small TV cameras set up in the test area to videotape your movement during the test. This recorded movement, analysed with the EEG recording, may help the doctor identify your type of seizure.
- You will be asked to lie on a stretcher where the technician will then measure your head and mark where the metal discs will be placed. These small metal discs, called electrodes, will be applied to various places on the scalp with a special cream. This painless process takes 15-20 minutes.
- You will be instructed to keep your eyes closed and to remain still and relaxed throughout the examination.
- Various procedures may be used during the test to stimulate the brain or to trigger certain brain waves and produce clearer wave patterns.
- You may be asked to open and close your eyes several times.
- You may be instructed to breath deeply through your mouth for short time. This may cause a slight dizzy feeling or numbness in the hands or feet. These are natural reactions and will subside once the deep breathing is over.
- A bright, flashing light may be placed in front of your eyes which may cause you to see different geometric designs and patterns of light.
- If your doctor ordered a sleep test, you will be given a mild sedative to help you fall asleep during the examination.
- These different procedures are done in order to compare brain activity under a wide variety of conditions.
- Inaccurate results can be caused by an irregular heartbeat, sweating, eye movement, eye blinking, muscle tension, sucking movements, chewing or any movement. Therefore, to help ensure accurate results, you must relax and breath normally, stay quiet and still, and carefully follow the technician's instructions.
- The entire EEG test takes 60-90 minutes.
After an EEG
- The electrodes will be removed from your head. There may be some stickiness from the cream used to place the electrodes: wash your hair when you get home.
- You should be able to resume normal activities, unless told otherwise by the doctor or technician.
Personnel
- EEG Technologists and Technicians
- help physicians diagnose epilepsy;
- take your medical history;
- prepare the EEG test;
- operate the EEG machine to record electrical impulses transmitted by the brain and nervous system;
- apply electrodes to designated spots on your head;
- prepare data for doctors to interpret.
- Physicians who specialize in EEGs
- read and interpret the results of the EEGs;
- supervise the EEG technicians.
Payment
An EEG test is fully covered by the Ontario Health Insurance Plan (OHIP).
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