An electroencephalogram (EEG) is a diagnostic test that measures the electrical activity of the brain (brainwaves) using highly sensitive recording equipment attached to the scalp by fine electrodes. It is used to diagnose neurological conditions.
EEGs can be recorded by 24-hour ambulatory cassette or digital recorders and offer the ability to record the EEG on a long-term outpatient basis. Ambulatory EEG monitoring is accomplished by a recorder that continuously records brain wave patterns during 24 hours of an individual’s routine daily activities and sleep. The monitoring equipment consists of an electrode set, preamplifiers, and a recorder. The electrodes attach to the scalp, and their leads are connected to a recorder, usually worn on a belt. Ambulatory monitoring is not necessary to evaluate most seizures, which are usually readily diagnosed by routine EEG studies, physical examination, and history.
Ambulatory EEG monitoring is, however, a diagnostic procedure for individuals in whom a seizure diathesis is suspected but not defined by history, physical examination, or resting EEG. Ambulatory EEG monitoring may facilitate the differential diagnosis between seizures and syncopal attacks, sleep apnea, cardiac arrhythmias, or hysterical episodes. The test may also allow the professional provider to identify the epileptic nature of some episodic periods of disturbed consciousness, mild confusion, or peculiar behavior, where resting EEG is not conclusive. Additionally, it may also estimate seizure frequency, which may at times help to evaluate the effectiveness of a drug and determine its appropriate dosage.
EEG video monitoring combines the simultaneous recording of the EEG and video monitoring of behavior. This allows for correlation of ictal and interictal electrical events with demonstrated or recorded seizure symptomology. The combination of electroencephalographic and video monitoring of an individual is useful in the initial diagnosis of epilepsy, particularly where previous attempts to define or characterize the seizure activity have proven inconclusive. Beyond the initial diagnosis of epilepsy, the combination is useful in uncharacterized events, identifying affected areas of the brain, and confirmation and/or differentiation between epileptic and nonepileptic events. Additionally, the study may be used in the pediatric population where history and clinical descriptions of seizure activity are difficult to obtain.
It is anticipated that clinical examination and routine electroencephalographic studies be used before employing electroencephalographic and video monitoring, and that this study be essential to the establishment of an appropriate treatment regimen.