Learn something new every day
More Info... by email
Every person’s brain has electrical signals that move in certain patterns. An electroencephalograph (EEG), also called an electroencephalogram, records these signals through electrodes, or electrical conductors. The signals are sent to a computer, which shows the electrical impulses as a group of wavy lines.
This test is generally performed for diagnostic purposes. If a patient is having seizures, the electroencephalograph can detect this. Patients who have suffered from head injuries and general confusion may also undergo an EEG. Other conditions an electroencephalograph may evaluate include tumors, Alzheimer’s disease, and infections.
Patients who suffer from sleep disorders, such as insomnia, may also undergo this diagnostic test. It can be used to evaluate brain activity during unconsciousness. If a patient is in a deep coma, an electroencephalograph may be performed to determine whether the patient has any brain activity.
The results of an EEG will typically take a few days to process. A neurologist will interpret the results. If the results are considered to be abnormal, further tests may be needed to provide a specific diagnosis.
Sometimes, the test results may not be accurate. This can occur if the patient moved too much during the test, or if his hair was oily, dirty, or coated with cosmetic products. Some medications, such as sedatives and antiepileptic drugs, can also interfere with the accuracy of results. Patients who have hypothermia, also known as a low body temperature, or who are unconscious due to drug poisoning may be unable to undergo this test.
To ensure the results are as accurate as possible, patients typically need to undergo several preparatory steps prior to the electroencephalograph. They may be advised to stop taking certain medications for a period of time. Patients usually also need to refrain from consuming caffeine for eight hours prior to the test. They should wash their hair and avoid using conditioner and other hair care products, as these may interfere with the electrodes. Patients may also be requested to sleep as little as possible the night before, in order to evaluate certain patterns of brain activity.
In the procedure itself, the patient lies on a table or bed with his eyes closed. Electrodes will be attached to his head with a sticky paste. Patients should refrain from moving around or speaking unless requested to. This test may take one to two hours.
The technologist may ask the patient to look at a strobe light. Patients may be asked to hyperventilate, or breathe rapidly. These activities help to record certain types of electrical activity. Some patients may need to sleep during the exam. For those that are unable to fall asleep, a sedative may be administered.
There are minimal risks associated with an electroencephalograph. A patient with a seizure disorder who is asked to hyperventilate or look at a strobe may go into a seizure. If a sedative was administered, the patient will be unable to drive home, and will need someone to do that for him.