Your healthcare provider may monitor you through a window in an adjoining room to observe any movements that can cause an inaccurate reading, such as swallowing or blinking.
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The EEG may also be used to monitor blood flow in the brain during surgical procedures. The EEG may also be used to determine the overall electrical activity of the brain (for example, to evaluate trauma, drug intoxication, or extent of brain damage in comatose patients). The test can also be used to diagnose other disorders that influence brain activity, such as Alzheimer's disease, certain psychoses, and a sleep disorder called narcolepsy. People with lesions of their brain, which can result from tumors or stroke, may have unusually slow EEG waves, depending on the size and the location of the lesion. When epilepsy is present, seizure activity will appear as rapid spiking waves on the EEG. The EEG is used to evaluate several types of brain disorders.