The Electroencephalogram (EEG) is a medical test used to gauge the electrical action of the brain, via electrodes applied to your scalp. This process is completely painless and can be perform without shaving any of your hair. EEG can help diagnose a number of conditions, including epilepsy, sleep disorders and brain tumours. Another name for EEG is brain wave test.
Conditions diagnosed by EEG
Ordinary brain waves happen at a rate of up to 30 per second, but in someone with epilepsy - for example - the EEG may demonstrate bursts of abnormal discharges in the form of spikes and sharp wave patterns. Suspected epilepsy is the most common reason for an EEG. Other conditions that may be diagnosed with the aid of an EEG include:
- Sleep disorders
- Head injuries
- Brain infection
- Brain haemorrhage
- Alzheimer's disease
- Degeneration of brain tissue
- Metabolic conditions that affect brain tissue
- Hormonal conditions that affect brain tissue
- Certain disorders of the central nervous system
- Brain tumours
- Brain death
Your hair must be painstakingly clean and recently shampooed. A number of electrodes are applied to your scalp. A gel may be applied to help the electrodes to stick firmly in place. You will need to lie quietly to shun any electrical intervention from muscle contractions. Sometimes, you may be asked by the doctor to open and close your eyes and to respire heavily. Lights may be flashed before your eyes. An EEG usually takes from 30 to 60 minutes to complete. Sometimes, a sleep recording is also needed. If the patient is a baby or young child, it helps if the parents delay the child's nap until the time of the EEG. Sedatives may be needed if sleep won't come naturally during the test.
EEG is a secure test with no side effects. However, a person with epilepsy may experience a seizure, triggered by the various stimuli used in the procedure, including the flashing lights. (This is not seen as a 'complication' by medical staff, because a seizure during an EEG can greatly help in diagnosis.)