Electroencephalogram (EEG)

An electroencephalogram (EEG) is a test used to evaluate the electrical activity in the brain. Brain cells communicate with each other through electrical impulses, and an EEG can be used to help detect potential problems associated with this activity.

What is an EEG used for?

An EEG is used to help diagnose and monitor a range of conditions, including:

• Epilepsy and seizures
• Head injuries and concussions
• Stroke and cerebral vasculitis
• Brain tumors and cancer
• Infections such as meningitis and encephalitis
• Sleep disorders, including insomnia and sleep apnea
• Alzheimer's disease and other forms of dementia

How is an EEG performed?

An EEG is typically performed in a doctor's office or hospital setting. The test involves:

1. The placement of small electrodes on the scalp, usually 16-25 in number
2. These electrodes are attached to a machine that records the electrical activity of the brain
3. The patient is asked to sit or lie down and remain still during the test
4. The test may involve different stages, such as:
• Baseline recording: The patient is awake and relaxed
• Activation procedures: The patient may be asked to breathe deeply, look at a flashing light, or perform other tasks to stimulate brain activity
• Sleep recording: The patient may be asked to fall asleep during the test
5. The entire procedure typically takes 30-60 minutes

What do EEG results show?

EEG results can show a range of information, including:

• Brain wave patterns: The different stages of sleep and wakefulness are associated with distinct brain wave patterns, including alpha, beta, theta, and delta waves
• Abnormalities: Such as spikes, sharp waves, or slow waves, which can indicate conditions such as epilepsy or brain damage
• Asymmetry: Differences in brain activity between the two hemispheres of the brain

Types of EEG

There are several types of EEG, including:

• Resting EEG: The patient is awake and relaxed during the test
• Sleep EEG: The patient is asleep during the test
• Ambulatory EEG: The patient wears a portable device that records brain activity over an extended period, usually 24 hours
• Video EEG: The patient's brain activity is recorded along with video footage of their behavior and movements

Risks and complications

The risks and complications associated with an EEG are minimal, but may include:

• Skin irritation or allergic reactions to the electrodes
• Discomfort or anxiety during the test
• In rare cases, an EEG can trigger a seizure in people with epilepsy

Interpretation of results

The results of an EEG are interpreted by a trained healthcare professional, usually a neurologist. The interpretation takes into account the patient's medical history, symptoms, and other test results.