Prevalence of non-convulsive seizure and other electroencephalographic abnormalities in ED patients with altered mental status.
Four 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.


OBJECTIVE
To identify the prevalence of NCS and other EEG abnormalities in ED patients with AMS.


METHODS
A 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.


RESULTS
prevalence 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.


RESULTS
Two 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).


CONCLUSIONS
The 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.
Department of Emergency Medicine, State University of New York, Downstate Medical Center, Brooklyn, NY, USA. Electronic address: Shahriar.zehtabchi@downstate.edu.
Shahriar
S
Zehtabchi
Samah G
SG
Abdel Baki
Ahmet
A
Omurtag
Richard
R
Sinert
Geetha
G
Chari
Shweta
S
Malhotra
Jeremy
J
Weedon
André A
AA
Fenton
Arthur C
AC
Grant
D000367:Age Factors; D000368:Aged; D001921:Brain / Q000503:physiopathology; D003244:Consciousness Disorders / Q000453:epidemiology* / Q000503:physiopathology; D004569:Electroencephalography / Q000706:statistics & numerical data; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012640:Seizures / Q000453:epidemiology* / Q000503:physiopathology