What does EEG stand for?
EEG stands for electroencephalogram.
This a simple and painless test from which the electrical activity from the brain is recorded from the scalp by electrodes.
Why have I been sent for an EEG?
There are many reasons why people are referred for this test, most commonly it is used in the investigation of people who have had or are currently experiencing seizures or blackouts.
The EEG
Before:
- No special preparation is needed before an EEG.
- Please try to attend with clean hair, free from styling products.
- Medications to be taken as normal before an EEG.
- You will have the opportunity to ask any questions you would like to.
- Video will be recorded along with your brain activity, this is to assist interpretation. Your consent will be required for this, which will be explained further when you attend for
your appointment.
During
- EEG will be performed by a Clinical Physiologist who will firstly ask routine questions regarding your medical history, current medications, and current symptoms.
- Your head will then be measured using a pencil and tape measure, before you will be asked to sit on a couch.
- 23 electrodes will then be placed at specific points of your scalp using a cotton bud to clean the scalp, then a conductive paste to attach each electrode separately.
- 2 electrodes will be placed on your shoulders to record heart activity (ECG).
- Once all wires are attached the test will take approximately 20 minutes during which you will be asked to sit quietly.
- You will be asked to open and close your eyes briefly every few minutes.
- Part way through recording you may be asked to perform a period of deep breathing, and to undertake a period of looking at flashing lights (Activation procedures-see
below). - If you fall asleep during EEG the recording may be prolonged to 30 minutes.
After
- At the end of the EEG all of the electrodes will be removed and your head cleaned using wet cotton wool.
- Your head will feel sticky, but this will come out when you wash your hair.
There are no side effects to having an EEG and you can go home or carry on with your daily routine as usual.
Results
- No results available on the day for outpatient appointments.
- A technical report will be written by the clinical physiologist who performed your test following the EEG.
- The EEG will then be reviewed by a consultant neurophysiologist, and the findings written and sent to the doctor who referred you for the test.
- The doctor who sent you for this test will be the doctor who will discuss results with you.
Activation procedures
Hyperventilation (HV)
- HV is an activation procedure carried out during routine EEG recording, and is performed approximately half way through the recording.
- Usually performed for 3 minutes, but may be prolonged if deemed necessary by the performing physiologist.
- Can cause light headedness or tingling; this is normal and will quickly pass following HV.
- There is a minimal risk certain types of seizures may be provoked by performing HV, however the physiologist will closely monitor you at all times.
- Your consent will be required for this, which will be explained further when you attend for your appointment and at the point of starting HV.
Photic stimulation (PS)
- PS is used to assess whether you have a sensitivity to
flashing lights. - This is performed by placing a light in front of your eyes and showing a flashing light at increasing rates over a period of several minutes.
- There is a minimal risk certain types of seizures may be provoked by performing PS, however the physiologist will closely monitor you at all times.
- Your consent will be required for this, which will be explained further when you attend for your appointment and at the point of starting PS.
Will having a seizure during the EEG affect my right to
drive?
If you are concerned about the risk of having a seizure, it is advisable to talk to the doctor who has asked you to have the test.
For further information please see website links below: