Electroencephalogram (EEG) Test is used to record and measure the electrical activity of the brain. Special Sensors (Small, Flat Metal Disc) called electrodes are attached to the scalp of the brain and hooked by wires to a computer that records the brain’s activity on the screen as wavy lines with peaks and valleys. An abnormal pattern of these wavy lines helps the doctor to quickly assess any irregularity which may be a sign of Seizures or other Brain Disorders. This test can also help the surgeons to monitor the brain activities at the time brain surgeries. EEG test Cannot measure intelligence or detect mental illness but this test can confirm brain death of a patient who is in persistent coma condition.
EEG is used to confirm or rule out various conditions including :
- Epilepsy / Any other Seizure Disorders
- Encephalopathy (Disease that causes Brain Dysfunction)
- Encephalitis (An Inflammation of the Brain)
- Head Injury
- Brain Tumour
- Memory Problems
- Sleep Disorders
People with Epilepsy or another seizure disorders may have a seizure episodes because of some stimuli such as a flashing light. However, an appropriate medical care by the technician performing the EEG is provided, if needed.
How to prepare for an EEG Test?
- Wash your hair the night before or the day of the test, but don't use any conditioners, hair creams, sprays or styling gels. Hair products can make it harder for the sticky patches that hold the electrodes to adhere to your scalp.
- Avoid anything with caffeine on the day of the test, because caffeine can affect the test results.
- Take your usual medications unless instructed otherwise.
If you are supposed to sleep during your EEG test, your doctor may ask you to sleep less or even avoid sleep entirely the night before your EEG.
After the EEG is over, you can continue with your regular routine for the day. However, if you were given a sedative, the medication will remain in your body for a little while. This means that you will have to bring someone with you so they can take you home after the test. You will need to rest and avoid driving until the effect of medication fade away.
What is the procedure of EEG Test?
An EEG may be given at a hospital, at your doctor’s office, or at a laboratory by a specialized technician. It usually takes 30 to 60 minutes to complete. The test typically involves the following steps:
- You’ll be asked to lie down on your back in a reclining chair or on a bed.
- The technician will measure your head and mark where the electrodes will be placed. These spots are then scrubbed with a special cream that helps the electrodes get a high-quality reading.
- The technician will put a sticky gel adhesive on 16 to 25 electrodes. They will then be attached to various spots on your scalp.
- Once the test begins, the electrodes send electrical impulse data from your brain to the recording machine. This machine converts the electrical impulses into visual patterns that can be seen on a screen. These patterns are saved to a computer.
- The technician may instruct you to do certain things while the test is in progress. They may ask you to lie still, close your eyes, breathe deeply, or look at stimuli (such as a flashing light or a picture).
- After the test is complete, the technician will remove the electrodes from your scalp.
During the test, very little electricity is passed between the electrodes and your skin, so you’ll feel very little to no discomfort.
What are the Expected Results?
A neurologist (someone who specializes in nervous system disorders) interprets the recordings taken from the EEG and then sends the results to your doctor. Your doctor may schedule an appointment to go over the test results with you.
Electrical activity in the brain is seen in an EEG as a pattern of waves. Different levels of consciousness, such as sleeping and waking, have a specific range of frequencies of waves per second that are considered normal. For example, the wave patterns move faster when you’re awake than when you’re asleep. The EEG will show if the frequency of waves or patterns are normal. Normal activity typically means you don’t have a brain disorder.
Abnormal EEG results may be due to:
- Epilepsy or another seizure disorder
- Abnormal bleeding or hemorrhage
- Sleep disorder
- Encephalitis (swelling of the brain)
- A tumor
- Dead tissue due to a blockage of blood flow
- Alcohol or drug abuse
- Head Injury
It’s very important to discuss your test results with your doctor. Before you review the results with them, it may be helpful to write down any questions you might want to ask. Be sure to speak up if there’s anything about your results that you don’t understand.