Electroencephalogram (EEG)
Types of EEG
The main types of EEG are explained below.
Routine EEG
A routine EEG recording lasts for about 20 to 40 minutes.
During the test, you'll be asked to rest quietly and open or close your eyesfrom time to time. In most cases, you'll also be asked to breathe in and outdeeply (known as hyperventilation) for a few minutes.
At the end of the procedure a flashing light may be placed nearby to see if this affects your brain activity.
Sleep EEG or sleep-deprived EEG
A sleep EEG is carried out while you're asleep. It may be used if a routine EEG doesn't give enough information, or to test for sleep disorders.
In some cases, you may be asked to stay awake the night before the test to help ensure you can sleep while it's carried out. This is called a sleep-deprived EEG.
Ambulatory EEG
An ambulatory EEG is where brain activity is recorded throughout the day and night over a period of one or more days. The electrodes will be attached to asmall portable EEG recorder that can be clipped on to your clothing.
You can continue with most of your normal daily activities while the recording is being taken, although you'll need to avoid getting the equipment wet.
Video telemetry
Video telemetry, also known as video EEG, is a special type of EEG where you're filmed while arecording is taken. This can help provide more information about your brain activity.
The testis usually carried out overa few days while staying in a purpose-built hospital suite.
The EEG signals are transmitted wirelessly to acomputer. The video isalso recorded by the computer and kept under regular surveillance by trained staff.
Medically Reviewed by a doctor on 21 Dec 2018
Introduction
Read about why an electroencephalogram (EEG) recording may be needed and find out what happens before, during and after the test.
When an EEG is used
An EEG can be used to help diagnose and monitor a number of conditions affecting the brain.It may helpidentify the cause of certain symptoms such as seizures (fits) or memory problems or find out more
Preparing for an EEG
Your appointment letter will mention anything you need to do to prepare for the test.Unlesstold otherwise, you can usually eat and drink beforehand and continue to take all your normal medication.To h
How an EEG is carried out
There are several different ways an EEG recording can be taken. The clinical neurophysiologist will explain the procedure to you andcan answerany questions you have.You'll also be asked whether you gi
Types of EEG
The main types of EEG are explained below.Routine EEGA routine EEG recording lasts for about 20 to 40 minutes.During the test, you'll be asked to rest quietly and open or close your eyesfrom time to t
What happens after an EEG
When the test is finished,the electrodes will be removed and your scalp will be cleaned. Your hair will probably still be a bit sticky and messy afterwards, so you may want to wash it when you get hom
Are there any risks or side effects?
The EEG procedure is painless, comfortable and generally very safe. No electricity is put into your body while it's carried out. Apart from having messy hair and possibly feeling a bit tired, you won'
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