Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society
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J Clin Neurophysiol · Sep 2004
ReviewEmergency EEG and continuous EEG monitoring in acute ischemic stroke.
There is physiologic coupling of EEG morphology, frequencies, and amplitudes with cerebral blood flow. Intraoperative continuous electroencephalographic monitoring (CEEG) is an established modality that has been used for 30 years to detect cerebral ischemia during carotid surgery. These facts have generated interest in applying EEG/CEEG in the intensive care unit to monitor cerebral ischemia. ⋯ This review presents evidence that EEG/CEEG adds value to early diagnosis, outcome prediction, patient selection for treatment, clinical management, and seizure detection in AIS. Research studies correlating EEG/CEEG and advanced imaging techniques in AIS are encouraged. Improvements in real-time ischemia detection systems are needed for EEG/CEEG to have wider application in AIS.
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Excellent early work on stupor and coma can be found (particularly with regard to anoxia) in the work of Fischgold and Mathis (1959) in France, and Pamela Prior in England (1973a). These workers correlated deepening levels of coma with particular EEG patterns, and the suppression of EEG reactivity. Alpha frequency patterns in coma (alpha coma), spindle-like sleep patterns in coma (spindle coma) and "triphasic waves" are among the wide variety of endocrine disorders discussed in case reports and series leading to identification of particular EEG patterns. ⋯ If etiology is known, EEG can often be a reliable predictor of outcome. EEG usually has little specificity with regards to etiology, but some patterns do favor particular diagnoses: for example, triphasic waves (TWs) are frequently seen with hepatic and renal insufficiency in young adults; spindle coma patterns are believed to indicate dysfunction at the brainstem level (Chatrian, 1990). EEG is most useful in differentiating organic from psychiatric conditions, in excluding nonconvulsive status epilepticus (NCSE), and in providing a rough guide as to the degree of cortical and subcortical dysfunction.
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J Clin Neurophysiol · Sep 2004
ReviewPrognostic determination in anoxic-ischemic and traumatic encephalopathies.
Clinical assessment of the unresponsive patient is limited to examination of brainstem reflexes and simple motor responses to stimulation. It is thus difficult, especially if brainstem functions are intact, to give early, accurate prognostic information on comatose patients. Neurochemical tests and imaging have not been validated and have significant limitations. ⋯ Persistent abnormalities of brainstem auditory evoked potentials and short-latency somatosensory evoked potentials reliably indicate the likelihood permanent vegetative state or death. Conversely, the presence of "cognitive" event-related brain potentials (e.g., P300 and mismatch negativity) reflects the functional integrity of higher-level information processing and, therefore, the likelihood of capacity for cognition. A combined clinical and electrophysiologic approach provides optimal prediction of outcome and level of disability.
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J Clin Neurophysiol · Sep 2004
ReviewContinuous EEG monitoring in the intensive care unit: an overview.
Due to technological advances, it is now feasible to record continuous digital EEG (CEEG), with or without video, in critically ill patients and review recordings remotely. Nonconvulsive seizures (NCSzs) are more common than previously recognized and are associated with worse outcome. The majority of seizures in ICU patients are nonconvulsive and will be missed without CEEG. ⋯ EEG patterns in encephalopathic or comatose patients are often equivocal. How aggressively to treat NCSzs and equivocal EEG patterns in these patients is unclear and requires further research. Real-time detection of ischemia at a reversible stage is technologically feasible with CEEG and should be developed into a practical form for prevention of in-hospital infarction in the near future.
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J Clin Neurophysiol · Sep 2004
ReviewData analysis for continuous EEG monitoring in the ICU: seeing the forest and the trees.
Continuous EEG monitoring (CEEG) is a powerful tool for evaluating cerebral function in obtunded and comatose critically ill patients. The ongoing analysis of CEEG data is a major task because of the volume of data generated during monitoring and the need for near real-time interpretation of a patient's EEG patterns. Advances in digital EEG data acquisition, computer processing, data transmission, and data display have made CEEG monitoring in the intensive care unit technically feasible. ⋯ These tools reduce the tremendous time burdens that accompany analysis of the complete CEEG data stream, and allow bedside personnel and nonexpert staff to potentially recognize significant EEG changes in a timely fashion. This article uses literature review and clinical case examples to illustrate techniques for the display and analysis of intensive care unit CEEG recordings. Areas requiring further research and development are discussed.