An electroencephalogram, or EEG, is one of the available tests used to diagnose epilepsy.
When epilepsy is suspected, one of the more common diagnostic tests used is the electroencephalogram. The electroencephalogram, or EEG, measures and records the electrical activity of the neurons in the brain. An EEG can tell your healthcare provider if there is abnormal electrical activity in the brain and, in some cases, the types of seizures you might be experiencing.
An EEG can also help your healthcare provider identify any other abnormalities existing in the brain, such as a coma, brain death, or the presence of a tumor or a stroke.
An EEG may seem a little foreboding due to the electrodes and wires involved, however it is an important -- and painless -- procedure that will help your neurologist identify any abnormal activity occurring in your brain.
EEGs are typically performed in a neurology clinic by a trained technician or in the hospital on an outpatient basis. You are fully awake for this procedure. Your head will be measured and your scalp will be carefully marked by a crayon or washable marker in order to designate the places to attach the electrodes. Next, electrodes will be secured to the scalp using a special adhesive that can be washed out of the hair. These electrodes are connected by a wire that is routed to a computer that will analyze the electrical activity occurring in your brain.
The entire EEG should take between one and two hours. During this time, you may be asked to blink or breath deeply or rapidly to see how your brain responds. In some cases, the neurologist might want to record your brain activity while you sleep. You will be notified of this before the EEG is conducted. The results of your EEG are recorded in a computer, or sometimes paper, and will be read by the neurologist.
An electroencephalogram (EEG) evaluates electrical activity produced by the brain, which can signify or rule out certain conditions, most commonly seizure disorders. The EEG takes about an hour to complete, and the results are automatically sketched on paper, while a video monitor records the movement of the patient, which can disrupt the test.
It is easier to read an EEG of an adult, since there is less variance in brain activity. This is not true of an EEG test used on a child. There is often so much variance in brain activity that an EEG in children may be consistent with epilepsy where none exists. Generally, seizure disorder in children, without the presence of identifiable seizures requires testing other than an EEG to have confirmed results.
As a test progresses, if it is used to examine seizure disorder, a person may be directed to look at flashing lights, which might trigger a seizure. The lights are stopped if evidence from the EEG shows that a person is in pre-seizure mode. Thus the person generally doesn’t have a seizure, but shows electrical activity consistent with what would become a seizure.
An EEG may also be used to evaluate other conditions. For example, people who come to a hospital in an altered state of consciousness, perhaps after a head injury, would probably have an EEG performed. Migraines have been shown to have a similar EEG pattern, and people who suffer from them may have an EEG to confirm diagnosis. Some psychiatric disorders that are organic in nature can also show a distinct pattern of electrical activity.
People with tumors, or with brain abscesses may also show lack of electrical activity in some aspects of the test. As well, an EEG can measure total lack of brain activity, confirming the death of a patient.
Generally an EEG is most helpful in measuring a patient who can be compliant. A screaming child, for example, or a patient with extreme mental disturbance, who cannot remain calm, will have a corrupted EEG test. For children, an EEG is usually scheduled during a child’s naptime.
Not all brain functions can be measured by an EEG. X-rays or more complex scans would probably follow an EEG that suggests a tumor or cranial swelling in order to confirm the diagnosis. The electrical patterns of the brain are measured against “normal scans.” Thus the EEG can be an excellent tool for suggesting variance. However, physicians may have to look further to confirm the actual meanings of variance.