EEG, or electroencephalogram, tests detect abnormalities in a person’s brain waves. During such a procedure, electrodes are pasted on the scalp to detect small electrical charges that result from brain activity. These charges appear as a printable record or a computer graph that is interpreted by a healthcare professional. In this guide, readers can learn the answer to the question What EEG (electroencephalogram) Test Does?
Who Needs an EEG?
EEGs are used to evaluate different brain conditions. In epileptic patients, seizures appear as spiking waves on the EEG graph. A person with brain lesions, which often occur due to stroke or the presence of a tumor, may have slow waves. These tests can be used to detect other disorders, such as narcolepsy, Alzheimer’s disease, and some psychoses. EEGs may be used to assess a patient’s overall brain activity or to observe blood flow during a surgical procedure, and healthcare providers sometimes recommend them for other reasons.
EEGs have been used for years, and they are generally seen as safe. The test itself does not cause discomfort, nor do the electrodes. There’s no risk of electric shock, but the test can, in rare cases, cause seizures in sensitive individuals. Other risks depend on the patient’s medical condition, and patients should discuss their concerns before the procedure begins.
Factors Interfering With EEG Readings
Some conditions and factors may cause inaccurate EEG readings. They include:
- Low blood sugar
- Eye or body movement during the test
- Flashing or bright lights
- Sedatives and other medicines
- Coffee, cola, tea, and other caffeinated drinks
- Hair products or oily hair
Preparing for an EEG
Patients should ask their healthcare providers to tell them what to do before the EEG test. In most cases, patients will get the chance to ask questions, and they’ll have to sign a consent form. It’s best to wash the hair the night before and to avoid the use of hair conditioners, gels, and other products. Tell the provider about all prescription medicines, OTC products, and dietary supplements. Stop using medicines that can interfere with the test results if directed to do so, and don’t drink or eat anything caffeinated for eight to 12 hours beforehand. Some tests require the patient to get limited sleep the night before, and these requirements should be clearly outlined.
What to Expect
EEGs are often done in an outpatient setting, but some are done on an inpatient basis. The procedure may vary depending on the provider’s methods and the patient’s condition, and the provider can tell the patient what to expect. Most procedures follow this process:
- The patient relaxes in a recliner or on a bed.
- Up to 25 electrodes are attached to the scalp with paste or a cap.
- The patient relaxes, closes his or her eyes, and remains still.
- The provider may monitor the patient throughout the test.
- In some cases, patients are tested with stimuli to produce different types of brain activity.
These studies take anywhere from 45 minutes to two hours. If it’s a sleep-related condition, it may be done while the patient is asleep. This test is useful in diagnosing the extent of a brain injury or other conditions.
For more information on neurofeedback and EEGs, see the website for The Brain Performance Center.