Overview of Electroencephalogram (EEG) | Neurology

Electroencephalogram

What is an electroencephalogram (EEG)?

An electroencephalogram (EEG), is a test that estimates the electrical activity of the brain. It can be done to diagnose or observe diseases that affect the brain, such as epilepsy and sleep disorders. Your doctor will inform you if you need an EEG. The loads are stretched and appear on the computer screen as a graph or a recording on paper. Then your healthcare provider will explain the reading to you.

During an electroencephalogram (EEG), your healthcare provider will usually estimate the activity of 100 pages or computer screens. He or she pays special attention to the primary waveform but also examines responses to stimuli such as brief bursts of energy and flashing lights.

Purpose of electroencephalogram

The electroencephalogram (EEG) is used to identify problems associated with certain brain disorders in the electrical activity of the brain. Measurements given by EEG are used to confirm or rule out various conditions:

  • Seizure disorders (such as epilepsy)
  • Head injury
  • Encephalitis (inflammation of the brain)
  • Brain tumor
  • Encephalopathy (a disease that causes brain dysfunction)
  • Memory problems
  • Sleep disorders
  • Stroke
  • Dementia

When someone is in a coma, an EEG can be done to determine the level of brain activity. This test can also be used to monitor activity during brain surgery.

Where is electroencephalogram (EEG) tests done?

The EEG is usually performed in the hospital at the outpatient clinic. People with epilepsy have told us that it would be helpful for them to go on a date with someone. Some people are very tired of this process and are less likely to have seizures during the test. It may help to plan how you will get home after your appointment.

You may be asked to bring some simple portable recording equipment with you. You will be shown how to operate it.

Risk factors

An electroencephalogram has been done for many years and is considered a safe procedure. The test does not cause any discomfort. Electrodes record activity. They do not produce any sensation. Also, there is no risk of electric shock.

Certain factors or conditions can interfere with the reading of the EEG test. Besides these:

  • Low blood sugar (hypoglycemia) created by fasting
  • Body or eye movement through the tests (but this will rarely, if ever, significantly prevent the interpretation of the test)
  • Lights, especially bright or flashing ones
  • Certain drugs, such as sedatives
  • Drinks such as coffee, cola, and tea (these beverages may occasionally alter EEG results, which does not significantly interfere with test interpretation)
  • Oily hair or the behavior of hair spray

Procedure

Preparing for electroencephalogram

The patient is told when the electroencephalogram is scheduled.

  • If the patient is taking restrictive medications routinely to prevent seizures, antidepressants, or stimulants, they may be asked to stop taking these medications 1 to 2 days before the test.
  • The patient is told not to ingest caffeine before the test.
  • The patient should not use hair products (hairspray or gel) on the day of the test.
  • It is prudent to take the patient to the EEG site, especially if he or she wants to refrain from taking overdose medications.
  • If the patient has a sleep EEG, they may be asked to stay awake the night before the test.

During electroencephalogram

During an electroencephalogram, 20 electrodes are placed on your scalp while you lie on the exam table or in bed. Open your eyes first, then close them and relax. You may be asked to inhale deeply and quickly or to stare at a flashing light; both activities cause changes in brain wave patterns. If you are prone to epilepsy, you will rarely experience one during the test. If you are being evaluated for a sleep disorder, you may have a continuous EEG done at night while you sleep. This recording, which assesses other bodily functions such as breathing and pulse during sleep, is called polysomnography.

After electroencephalogram

Once the test is complete, the electrodes are removed and you are allowed to stand up. The results must be analyzed at a later stage by a neurologist (a doctor who specializes in brain disorders).

Generally, if there are no abnormalities in the electrical activity of the brain, the pattern of “peaks and valleys” traced by the electroencephalogram should be fairly regular. If excited, the pattern will show considerable variation and any deviation from the regular pattern may indicate abnormalities.

Results

Once the electroencephalogram results have been analyzed, they are sent to your doctor, who will accompany you. The EEG looks like a series of wavy lines. The lines will look different depending on whether you are awake or asleep during the test, but each state will have a general pattern of brain activity. If the regular brain wave pattern is disturbed, it could be a type of epilepsy or another brain disorder.

Having an abnormal EEG does not mean you have epilepsy. The test records what is happening in your brain at that moment. Your doctor will do other tests to confirm the diagnosis.

Complications

Complications of electroencephalogram (EEG) include:

  • You move too much.
  • You take certain medicines. This involves medicines used to treat seizures (antiepileptic medicines), sedatives, tranquilizers, and barbiturates.
  • You took coffee, soda, or tea, or you ate extra foods that have caffeine before the test.
  • You are careless from severe drug poisoning or very low body temperature (hypothermia).
  • Your hair is dirty, oily, or treated with hair spray or other hair products. This can create a problem with how the electrodes are placed.

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