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Electroencephalograph (EEG)

Also referred as

Electroencephalogram

For men & women

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An Electroencephalograph (EEG) is a non-invasive, painless, and completely safe imaging test that measures electrical activity in the brain. It records electrical impulses, which can be seen as wavy lines on an EEG recording, helping diagnose and monitor neurological disorders such as epilepsy, seizures, and stroke. It also helps study sleep patterns, cognitive processes, and brain function.

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Understanding Electroencephalograph (EEG)

An Electroencephalograph (EEG) test records the overall electrical activity of the brain. It helps diagnose and monitor a range of conditions affecting the brain, such as epilepsy (seizures), and other disorders affecting brain activity, such as Alzheimer’s disease, sleep disorders, or psychoses. It may also be used to evaluate symptoms like abnormal movements or behavior, cognitive decline, unexplained loss of consciousness or syncope, confusion, disorientation, etc., and the extent of brain damage in an individual in a coma.

During an EEG test, small sensors are placed on your scalp to pick up the electrical signals produced by the brain. These signals will be recorded by a machine and are looked at by a doctor. They indicate how well different areas of your brain are functioning.

You should wash your hair a day before the test and avoid using products such as conditioner, hairspray, or gel. You should also avoid consuming food or drinks that have caffeine for at least 8 to 12 hours before the test. Tell your doctor about all your medications or supplements, as these may affect the test results, potentially requiring adjustments or temporary discontinuation.

Interpretation of the test results requires professional expertise. Do not self-medicate and consult your doctor to understand your test results correctly.

Disclaimer: You must visit your nearest Tata 1mg partnered lab facility for radiology tests.

What does Electroencephalograph (EEG) measure?

The Electroencephalograph (EEG) is an imaging test that utilizes a machine consisting of an amplifier, computer console, and monitor. During the procedure, the electrodes are placed on the scalp to detect electrical signals produced by neurons, which are amplified and recorded. The resulting waveforms are displayed for interpretation, allowing doctors to analyze brain function and make informed decisions. This test measures the frequency, amplitude, and patterns of brain waves, providing insight into the brain's overall function. It can also help detect abnormalities like seizure activity, encephalopathy, and sleep disorders. EEG plays a pivotal role in understanding neurological health by capturing real-time brain wave patterns.

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FAQs related to Electroencephalograph (EEG)

What is the Electroencephalograph (EEG)?

The Electroencephalograph (EEG) is a non-invasive test that measures electrical activity in the brain using small electrodes placed on the scalp. It helps diagnose various neurological conditions such as epilepsy, encephalopathy, migraine, etc.

Why is an EEG performed?

The EEG is commonly performed to diagnose seizure disorders, investigate unexplained neurological symptoms (like confusion or fainting), monitor brain activity after an injury, evaluate sleep disorders, and assess brain function in various medical conditions.

How should I prepare for the test?

Before the EEG, wash your hair and avoid using hair products like gels or sprays. Inform your doctor about any medications you take, especially those affecting brain activity. Ensure you get adequate rest the night before the test.

Can I eat or drink before the test?

You can usually eat and drink before the test, but it's best to consult your doctor for specific instructions. However, avoiding caffeine for at least 8-12 hours before the test is advised.

Does the EEG test hurt?

No, the EEG test is painless and non-invasive. You may feel slight pressure when the electrodes are applied to your scalp, but it should not cause discomfort.

How long does the test take?

The Electroencephalograph (EEG) test may continue until clear images of the intended areas are obtained.

What can I expect during the test?

During the test, you’ll be asked to lie down comfortably. Electrodes will be placed on your scalp, and you may be asked to perform specific tasks, such as closing your eyes, opening them, or even breathing rapidly to stimulate brain activity.

What happens after an EEG test?

After the EEG, the technician will remove the electrodes and clean your scalp. Unless your technician tells you otherwise, you can go home and go about your day. Your hair and skin might feel sticky from the adhesive, so you may want to wash your hair once you’re home.

What happens if abnormalities are found in the EEG?

If abnormalities are detected, your doctor will discuss the findings and recommend further tests or treatments based on your specific condition.

What types of EEGs are there?

There are several types of EEGs, including routine, sleep, prolonged, video, and ambulatory EEGs. Each type is designed for specific purposes and tailored to address different clinical concerns.

Can children undergo an EEG test?

Yes, children can have EEGs. The process is similar, but special accommodations may be made to ensure they are comfortable and relaxed during the test.

Content created by

Dr. Swati Gupta (Anand)

MBBS, MD Lab Medicine

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Last Updated

18th Oct 2025