Patients with acute alteration in mental status from encephalopathy because of underlying metabolic–toxic or endocrine abnormalities are frequently seen in the acute hospital setting. A rapid diagnosis and correction of the underlying cause is essential as a prolonged state of encephalopathy portends a poor outcome. Correct diagnosis and management remain challenging because several encephalopathies may present similarly, and further laboratory, imaging, or other testing may not always reveal the underlying cause. EEG provides rapid additional information on the encephalopathic patient. It may help establish the diagnosis and is indispensable for identifying nonconvulsive status epilepticus, an important possible complication in this context. The EEG may assist the clinician in gauging the severity of brain dysfunction and may aid in predicting outcome. This review summarizes the current knowledge on EEG findings in selected metabolic and endocrine causes of encephalopathy and highlights distinct EEG features associated with particular etiologies.
*Department of Neurology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland, U.S.A.; and
†Division of Neurosciences Critical Care, Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, U.S.A.
Address correspondence and reprint requests to Roland Faigle, MD, PhD, Department of Neurology, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, MD 21224, U.S.A.; e-mail: email@example.com.
Supported by NIH/National Institute of Neurological Disorders and Stroke R25 training grant (to R. Faigle) and Research Funds from the University of Basel, the Scientific Society Basel, and the Gottfried Julia Bangerter-Rhyner Foundation (to R. Sutter).