brain, spinal cord, and nerve disorders
Tests for Brain, Spinal Cord, and Nerve Disorders
Electroencephalography
Electroencephalography (EEG) is a simple, painless procedure in which the brain’s electrical activity is recorded as wave patterns, printed on paper, and/or recorded in a computer. EEG can help identify the following: Seizure Disorders None Sleep disorders None Certain metabolic or structural disorders of the brain Rare conditions such as Diagnosis None For example, EEG can help identify where a seizure originates and show changes in electrical activity associated with confusion, which may result from disorders such as liver failure ( Hepatic Encephalopathy ) or certain drugs. For the procedure, an examiner places small, round adhesive sensors (electrodes) on the person’s scalp. The electrodes are connected by wires to a machine, which produces a record (tracing) of small changes in voltage detected by each electrode. These tracings constitute the electroencephalogram (the EEG). If a seizure disorder is suspected but the initial EEG is normal, another EEG is done after using a tactic that makes seizure activity more likely. For example, the person may be deprived of sleep, be asked to breathe deeply and rapidly (hyperventilate), or be exposed to a flashing light (stroboscope). Sometimes (for example, when behavior that resembles a seizure is difficult to distinguish from a psychiatric disorder), the brain’s electrical activity is recorded for 24 hours or longer while people are monitored in the hospital by a video camera. This procedure is called video EEG. The camera detects the seizure-like behavior, and by examining the EEG at that moment, doctors can determine whether brain activity indicates a seizure or is normal, suggesting a psychiatric disorder. An electroencephalogram (an EEG) is a recording of the brain’s electrical activity. The procedure is simple and painless. About 20 small adhesive electrodes are placed on the scalp, and the brain’s activity is recorded under normal conditions. Sometimes the person is exposed to various stimuli, such as bright or flashing lights, to try to provoke a seizure. 