Electroencephalogram (EEG)

What Is an EEG?

An electroencephalogram (EEG) is a diagnostic test that measures the electrical activity in the brain. Small sensors called electrodes are placed on the scalp to record brain impulses. The results show patterns of electrical activity that help doctors diagnose or monitor conditions affecting the brain.

Why an EEG May Be Recommended

Doctors may order an EEG if you are experiencing symptoms such as seizures, unexplained fainting, confusion, or sleep problems. EEG testing can help diagnose or monitor:

• Seizure disorders (such as epilepsy)
• Sleep disorders
• Head injuries
• Brain infections
• Brain tumors
• Alzheimer’s disease and other brain diseases
• Periods of unconsciousness or unexplained confusion
• Abnormal changes in body chemistry affecting the brain

An EEG may also be used to monitor brain activity during surgery.

What to Expect During an EEG

• A specially trained EEG technician will apply flat metal disks (electrodes) to your scalp using a sticky paste.
• These electrodes are connected to wires that transmit brain activity to a computer.
• The computer records your brain’s electrical signals as wavy line patterns.
• The procedure is safe and painless, and typically performed in a physician’s office, hospital, or specialized laboratory.

The test usually lasts 30 to 60 minutes, though some EEGs for sleep disorders may take longer.

After the Test

You can resume normal activities immediately after an EEG. The sticky paste used to hold the electrodes may leave residue, which can be washed off during your next shampoo. Your neurologist will review the results and discuss next steps in your care plan.