An electroencephalogram (EEG) evaluates electrical activity produced by the brain, which can signify or rule out certain conditions, most commonly seizure disorders. The test 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 than one of a child, since there is less variance in brain activity. There is often so much variance in brain activity that a reading taken on a child may be consistent with epilepsy where none exists. Generally, seizure disorder in children, without the presence of identifiable seizures, requires additional testing 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 the readings show that a person is in pre-seizure mode. This means that the person generally doesn’t have a seizure during the test, but that it 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 this test performed. Migraines have been shown to produce similar patterns, and people who suffer from them may have this test run to confirm a 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. An EEG can also measure a total lack of brain activity, confirming the death of a patient.
Generally, this test 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 corrupted results. For children, it 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 a test that suggests a tumor or cranial swelling in order to confirm the diagnosis. The electrical patterns of the brain are measured against “normal scans,” so the test can be an excellent tool for suggesting variance. Medical professionals may have to look further to confirm the actual meanings of these variations, however.
