• Shahriar Zehtabchi, Samah G Abdel Baki, Ahmet Omurtag, Richard Sinert, Geetha Chari, Shweta Malhotra, Jeremy Weedon, André A Fenton, and Arthur C Grant.
• Department of Emergency Medicine, State University of New York, Downstate Medical Center, Brooklyn, NY, USA. Electronic address: Shahriar.zehtabchi@downstate.edu.
• Am J Emerg Med. 2013 Nov 1;31(11):1578-82.

UnlabelledFour to ten percent of patients evaluated in emergency departments (ED) present with altered mental status (AMS). The prevalence of non-convulsive seizure (NCS) and other electroencephalographic (EEG) abnormalities in this population is unknown.ObjectivesTo identify the prevalence of NCS and other EEG abnormalities in ED patients with AMS.MethodsA prospective observational study at 2 urban ED. Inclusion: patients ≥13 years old with AMS. Exclusion: An easily correctable cause of AMS (e.g. hypoglycemia). A 30-minute standard 21-electrode EEG was performed on each subject upon presentation.Outcomeprevalence of EEG abnormalities interpreted by a board-certified epileptologist. EEGs were later reviewed by 2 blinded epileptologists. Inter-rater agreement (IRA) of the blinded EEG interpretations is summarized with κ. A multiple logistic regression model was constructed to identify variables that could predict the outcome.ResultsTwo hundred fifty-nine patients were enrolled (median age: 60, 54% female). Overall, 202/259 of EEGs were interpreted as abnormal (78%, 95% confidence interval [CI], 73-83%). The most common abnormality was background slowing (58%, 95% CI, 52-68%) indicating underlying encephalopathy. NCS (including non-convulsive status epilepticus [NCSE]) was detected in 5% (95% CI, 3-8%) of patients. The regression analysis predicting EEG abnormality showed a highly significant effect of age (P < .001, adjusted odds ratio 1.66 [95% CI, 1.36-2.02] per 10-year age increment). IRA for EEG interpretations was modest (κ: 0.45, 95% CI, 0.36-0.54).ConclusionsThe prevalence of EEG abnormalities in ED patients with undifferentiated AMS is significant. ED physicians should consider EEG in the evaluation of patients with AMS and a high suspicion of NCS/NCSE.© 2013.

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