This article includes discussion of EEG monitoring in the intensive care unit, cEEG monitoring in the ICU, and continuous EEG monitoring. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Over the past 2 decades, continuous EEG (cEEG) monitoring has become an established and widely used diagnostic tool in the intensive care unit (23). Among mechanically ventilated patients, the use of cEEG is associated with reduced inpatient mortality without significantly increased costs of admission (37). Although detection of nonconvulsive seizures and nonconvulsive status epilepticus are the commonest reasons for performing cEEG, there are many other reasons as well. In this article, the authors review indications for performing cEEG, appropriate durations for monitoring, and identification of patients who benefit most from this procedure.
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• Continuous EEG monitoring is defined as EEG monitoring performed for extended periods of time, ranging from hours to days.
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• Continuous EEG is used for a variety of conditions, including nonconvulsive seizure and status epilepticus detection, assessing response to therapy in patients in status epilepticus, monitoring level of sedation, ischemia detection, and prognostication.
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• Duration of cEEG monitoring depends on the clinical condition and goals of monitoring.
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• When used for seizure detection, specific EEG patterns can be used to predict the likelihood of seizure occurrence and can guide the decision of how long to continue cEEG monitoring.
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• Quantitative EEG techniques are becoming more widely used and may assist in more rapid seizure and cerebral ischemia detection.
Historical note and terminology
Techniques for the monitoring of cerebral electrical activity have existed in various experimental forms since the late 1800s. However, the clinical use of scalp EEG recordings in humans, primarily for the diagnosis and treatment of epilepsy, only became an established tool between 1930 and 1940 (04). By the 1960s, EEG became widely available, albeit primarily performed for brief periods of time. With the evolution of computer technology and the ability to digitally store large amounts of EEG data, the long-term recording of EEG data for critically ill patients became feasible in the 1990s. Over the past 20 years, cEEG use has expanded, and quantitative EEG techniques have become available to further aid in the interpretation of EEG data (47).