An EEG records the electrical activity of the brain through small electrodes placed on the scalp. It is painless, involves no radiation, and nothing is passed into the body.
Why it is requested
- Investigation of seizures and suspected epilepsy
- Classifying a seizure type to guide treatment
- Blackouts and episodes of altered awareness
- Assessment of confusion or reduced consciousness
- Monitoring in some brain conditions
Preparation
- Wash your hair the night before and use no oil, gel or spray
- Keep taking your usual medicines unless specifically told otherwise
- You may be asked to sleep less than usual beforehand, since drowsiness makes some abnormalities easier to see
- Eat normally — a missed meal can alter the recording
During the test
Allow around 45 to 60 minutes. You lie still with your eyes closed, and will be asked to breathe deeply for a short period and to look at a flashing light. Tell the technician beforehand if flashing lights have ever triggered a seizure.
