HomeHealth articlesseizureWhat Is Electroencephalography?

Electroencephalography - Procedure, Indications, and Possible Outcomes

Verified dataVerified data
0

4 min read

Share

Electroencephalography is a test to detect the functional and structural abnormalities of the brain by monitoring the pattern of the brain’s electrical activity.

Written by

Dr. Jayasree S

Medically reviewed by

Dr. Prakashkumar P Bhatt

Published At September 2, 2022
Reviewed AtSeptember 2, 2022

What Is Electroencephalography?

It is a neuro electrophysiologic study technique used to measure the electrical activity of the brain. It is measured by placing small recording electrodes on the scalp. The study intends to identify the pattern of communication between the different areas inside the brain. Even minute changes in electrical activity can be perceived during an EEG. This helps in diagnosing a wide range of brain disorders and neurological conditions. It is one of the most revolutionary innovations in unraveling the secrets of seizure attacks. With modern-day advancements, control and management of epileptic disorders are made easy with EEG.

What Does Electroencephalography Measure?

The brain cells, known as neurons, constantly send out electrical signals to communicate with each other. That is how they control and maintain the activities and functions of the body. These electrical signals are called nerve impulses. For each conscious or unconscious process happening in the body, including behavior and thoughts, a set of electrical impulses are passed among the nerve cells. During an EEG study, one can see the output pattern of these electrical impulses as waves or squiggles and come to various conclusions about brain activity. There will be multiple wave patterns in the study result as each of them corresponds to a specific region of the brain.

When Do You Conduct Electroencephalography?

There are a number of disease conditions that cause alterations in the electrical activity of the brain. The reading in an EEG shows variations if some part of the brain malfunctions. The pattern of brain waves varies depending on the individual's age and level of alertness. Doctor orders an electroencephalography test if one suffers from:

  • Diseases of the brain such as Alzheimer’s.

  • Epilepsy and seizures.

  • Head injuries.

  • Brain tumors.

  • Brain damage.

  • Memory loss.

  • Infections in and around the brain.

  • Degenerative brain disease, where nerve cells undergo gradual death on their own.

  • Frequent fainting spells.

  • Frequent headaches.

  • To monitor brain activity and blood flow to the brain during anesthesia and surgery.

  • Psychiatric diseases and mental confusion.

  • Sleep pattern abnormalities and sleep disorders. The study is conducted during sleep.

  • In individuals who are totally unresponsive to any stimuli following severe head injuries or other reasons, electroencephalography is conducted to show if there is any activity left inside the brain.

What Happens During the Electroencephalography Procedure?

The person undergoing the test is asked to lie down on a bed or sit back on a reclining chair. After coating it with a gel-type substance, the technician or nurse conducting the study will place several flat metal discs all over the scalp. Sometimes a specially designed electrode cap is also used, which can be worn on the head. All the electrodes will be connected to a machine by wires. One has to stay still the entire time of the procedure as changes in position may affect the study results. The electrical signals produced are passed on from the brain to the machine. Now the device will convert it into readable graphical patterns and display them on a screen or print them on paper.

According to the orders from the doctor, the patterns are recorded while sleeping, while awake, while breathing fast and deep, while blinking, or while looking at flashing bright lights. In certain situations, doctors might want to monitor the electrical pattern continuously for an entire night or conduct an ambulatory EEG (recording machine attached to the body) to monitor the brain activity for prolonged periods, like two to three days. Rarely fast breathing or having to look at the flashing lights for the study triggers seizures in individuals who tend to it, which is duly taken care of at the moment.

What Are the Possible Outcomes From an EEG Study?

For different levels of alertness, the brain sends out typical patterns of electrical impulses, which are marked as waves by the machine. One may notice alpha waves, beta waves, theta waves, and delta waves among the patterns. A qualified healthcare professional can identify the normal patterns in each state of consciousness. When the patterns show abnormal waves, the following are the common assumptions:

  1. Possibility of growth inside the brain, like a benign or a malignant tumor. Tend to show very slow EEG waves depending on the location and size of the lesion.

  2. Bleeding (hemorrhage) or a big blood clot inside the brain (hematoma).

  3. Possible damage in some brain areas due to obstruction in blood flow and death of nerve cells (stroke).

  4. Severe head injury affects the brain’s function (encephalopathy).

  5. Epilepsy and seizure disorders. It may show an increase in electrical activity. Sometimes, one may have seizures even if the EEG results are normal.

  6. Inflammatory swelling inside the brain (encephalitis).

  7. Sleep disorders like narcolepsy.

  8. Alcohol abuse and drug abuse.

  9. Cognitive dysfunctions like dementia.

What Are the Factors That May Interfere With the EEG Results?

Certain conditions may alter the usual EEG pattern of the individual and interfere with the study results. One should consciously avoid them while coming for the test. They can be:

  • Exposure to bright lights, especially of the flashing type.

  • Failing to keep still during the study.

  • Making rapid eye movements without being told to do so.

  • Low sugar levels in the blood due to poor food intake.

  • Use of sedatives or other medications without the knowledge of the technician or the doctor.

  • Excess intake of caffeine such as coffee, tea, or colas.

  • Chemicals or oil in the hair where the electrodes are placed.

Conclusion:

EEG is a very safe and risk-free procedure. Also, it is the best choice of study for seizure attacks. The entire study is totally painless and usually lasts for about thirty minutes to two hours. Furthermore, one should stress that there is no risk of getting electric shocks, as many fear. With the help of newer advancements like EEG, one has answers to what is happening in the brain during a seizure. Nowadays, EEG is extensively used for research purposes to understand the brain’s response to customized stimuli as well.

Frequently Asked Questions

1.

What Does An EEG Detect?

EEG tests reveal brain activity alterations that could help identify various brain conditions, particularly epilepsy and other seizure disorders. An electroencephalogram (EEG) uses tiny metal discs (electrodes) connected to the scalp to measure electrical activity in the brain.

2.

What Are The Conditions Diagnosed Using An EEG?

Sleep disorders (like narcolepsy).
Brain infection.
Brain hemorrhage.
Brain tumor.
Brain death.
Head injuries.
Certain disorders of the central nervous system.
Stroke.
Degeneration of brain tissue.
Metabolic conditions that affect brain tissue.
Alzheimer's disease.
Hormonal conditions that affect brain tissue.

3.

What Is A Normal EEG?

In most EEG, 8 Hz and higher frequency waves are standard in an awake adult. Although they typically occur in asleep children or adults, waves with a frequency of 7 Hz or less are frequently categorized as abnormal in awake adults. Regular brain waves occur at a rate of nearly 30 per second. The most frequent reason for an EEG is suspected epilepsy.

4.

Can EEG Be Painful?

No needles or other forms of electrical stimulation are used during the EEG. The procedure is entirely painless. An electroencephalogram (EEG) uses tiny metal discs (electrodes) connected to the scalp to measure electrical activity in the brain. The electrodes might feel strange and sticky on the scalp, but they shouldn't hurt in any other way. Throughout the test, one will not experience any discomfort.

5.

What Does An Abnormal EEG Indicate?

Abnormal EEG test results could be caused by:
Abnormal bleeding (hemorrhage).
Migraines.
Seizure disorder.
Tissue death due to a blood flow obstruction (cerebral infarction).
Drug or alcohol abuse.
Head injury.
An abnormal structure in the brain.
Swelling of the brain.

6.

How Long Does It Take For An EEG Test To Complete?

An electroencephalogram technician performs the test in a hospital, laboratory, or doctor's office. Typically, an EEG takes 30 to 60 minutes to complete. However, an ambulatory EEG will be prescribed if the doctor needs to track the brain activity over a longer period.

7.

Why Is MRI Better Than EEG?

The spatial resolution of MRI is greater than that of electroencephalography (EEG). In contrast to a standard EEG, which can only record contentious patterns like lateralized periodic discharges (LPDs), MRI with hyperintense lesions on FLAIR and DWI provides information about brain activity over a longer period.

8.

How Should I Prepare For An EEG?

Wash your hair the night before the test. Avoid using conditioner, oils, sprays, or gel on your hair. Ask the healthcare provider for specific instructions if you wear a hair weave.
Before the test, your doctor might ask you to stop taking a particular medication. Without consulting your provider, do not switch or stop taking any medications. List all of the medicines you take with you.
The test may require you to get some sleep. If so, you might be instructed to get less sleep the night before.
If you are advised to get as little rest as possible before the test, avoid eating or drinking anything containing caffeine, energy drinks, or other products that could keep you awake.

9.

Why Do They Use Flashlights During EEG?

A strobe light might occasionally be used during an EEG test. This checks to see changes in the electrical pattern of the patient’s brain. However, in the majority of the cases, it is not used while performing EEG and thus is not a common practice.

10.

Can I Eat Anything Before My EEG Test?

Before the test, you may eat. For eight hours before the test, avoid eating or drinking anything containing caffeine: no coffee, colas, or other stimulant-containing beverages. On the evening before and the day of the procedure, usually eat. Unusual results could result from low blood sugar. If you are supposed to sleep during the EEG, your doctor might advise you on how much to sleep.
Dr. Prakashkumar P Bhatt
Dr. Prakashkumar P Bhatt

Neurology

Tags:

eegseizure
Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Source Article ArrowMost popular articles

Do you have a question on

seizure

Ask a doctor online

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy