EEG (electroencephalogram)

What is an EEG?

An Electroencephalogram (EEG) records the electrical activity of the brain by picking up the electrical signals from the brain cells. These signals are picked up by electrodes attached to the head and are recorded on paper or on a computer. The recording shows how the brain is working.

What does an EEG show?

An EEG gives information about the electrical activity of the brain during the time the test is happening. When someone has an epileptic seizure their brain activity changes. This change, known as epileptiform brain activity, can sometimes be seen on an EEG recording. Some people can have epileptiform brain activity even when they do not appear to be having a seizure, so an EEG can be particularly useful for them. Epileptiform activity can sometimes be provoked (brought on) by deep breathing. The test may include deep breathing to see if epileptiform activity can be provoked and recorded.

EEG for the CESS Pathway

By looking at which electrodes are stimulated during a seizure can help workout which area of the brain the seizures are coming from. It also shows how a seizure develops and spreads. This is important information when deciding whether surgery is an option or which part of the brain future investigations should be focused.

Video Telemetry (VT)

Video Telemetry is where you will have the EEG electrodes attached to your head and also be filmed. For this to happen, you will need to come into hospital for a period of up to five days - usually on a Monday and discharged on a Friday. You will stay on the ward where a video camera is attached to your bed to capture your seizures. This is so that we can see when you’re having a seizure and from which part of the brain the abnormal epileptic electrical activity is coming from.

Ambulatory EEG/ Home LTM (Long Term electroencephalogram Monitoring)

An ambulatory EEG works in the same way as a normal EEG but is portable. During the test, you wear a small machine on a belt around your waist. Because it is portable you can move around and carry on with your normal day-to-day routine while the recording happens.

This type of EEG allows brain activity to be recorded for several hours, days or weeks. Because the brain activity is recorded for longer, there is more chance of a seizure being recorded than during the normal 30 minute test.

With LTM similar to ambulatory but like with VT you will also have cameras to record any seizures Sometimes this may be chosen instead of VT, If the VT hospital admission would be difficult, but VT is preferred option.