It can also be used to confirm brain death.
The test is used to help diagnose conditions such as seizures, epilepsy, head injuries, dizziness, headaches, brain tumors and sleeping problems. You may also be given a sedative to help you relax and sleep before the test begins.Īn electroencephalogram (EEG) is a noninvasive test that records electrical patterns in your brain. Your doctor may ask you to sleep as little as possible the night before the test if you have to sleep during the EEG. Normal electrical activity in the brain makes a recognizable pattern.Īvoid eating or drinking anything containing caffeine for at least eight hours before the test. Small metal discs with thin wires (electrodes) are placed on the scalp, and then send signals to a computer to record the results.
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Return to the Neurological Assessment page While the diagnosis of brain death does not require an EEG, it sometimes helps physicians feel confident that their is no normal brain activity. In fact, determination of brain death sometimes utilizes EEG to determine if there is any normal brain activity. For example, patients in coma are sometimes followed with EEG both to rule out subclinical seizures but also to evaluate for signs of recovery or brain death. The EEG is also used to evaluate other general changes in the activity of the brain. Therefore, the electroencephalogram is often used to diagnose and work-up patients who present with seizures or activity which is suspicious for epilepsy. Seizures, either generalized to the whole brain or focal, can often be seen as a characteristic rhythmic activity on the EEG which is quite different from the normal, seemingly random activity. Traditionally, besides general nervous system research, the EEG has been used to evaluate patients with epilepsy. What Is It Used For?Because the EEG reveals changes in the electrical activity of the neurons in the brain, it can aid in the diagnosis of various pathologies.
Patients with epilepsy will often undergo prolonged EEG monitoring in the attempt to catch a seizure on the EEG so that physicians can determine the location it originated from and other characteristics which may help in treatment. In some patients a short EEG will be taken while in others a prolonged EEG overnight or even longer may be required. The shape, frequency, amplitude and other characteristics of the trace from various regions of the brain are interpreted by a physician, usually a neurologist, and can reveal changes in the electrical activity of the brain.Įvaluation with an EEG varies depending on the clinical situation. The electrodes record electrical activity from the surface of the brain which is converted to a trace on the electroencephalogram output, traditionally wiggly lines on a sheet of paper although nowadays they are often simply displayed on a computer screen. In some cases where a continuous EEG is to be taken for a prolonged period of time, such as in a comatose head trauma victim, the electrodes can be implanted in the scalp as tiny needles. Generally, these are superficial stickers which are attached to wires which carry information to the monitor which displays the results. The EEG is performed by placing electrodes on the scalp. What Is It?An electroencephalogram (EEG) is a neurological test which records the electrical activity at the surface of the brain by way of electrodes placed on or in the scalp.