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After-Hours EEG

Relative Value of Emergent Routine Versus Prolonged EEG Recordings

Singh, Jaysingh*; Britton, Jeffrey; Alwaki, Abdulrahman; Singh, Priti§

Journal of Clinical Neurophysiology: January 2019 - Volume 36 - Issue 1 - p 32–35
doi: 10.1097/WNP.0000000000000529
Original Research

Objective: After-hours EEG is increasingly used in hospital patients. Although the detection of seizures and interictal epileptiform discharges has been shown to be higher with prolonged EEG (pEEG) than routine-duration EEG, the relative value for particular indications can inform utilization.

Method: The Mayo EEG Report System was queried for after-hours emergent routine EEG (ErEEG) and pEEG performed between January 2015 and June 2015. Total 296 after-hours ErEEG were identified, of which 140 converted into pEEG were included in the study for direct comparison of two modalities. Indications were categorized as: mental status changes, recent seizures rule out continued nonconvulsive seizures, spells, and prognosis after anoxic brain injury. Categorical data were analyzed using the McNemar and Fisher exact tests; a P value of 0.05 was considered significant.

Result: Prolonged EEG was superior to ErEEG for detection of interictal epileptiform discharges (61 vs. 48/140, P = 0.004) and seizures (29 vs. 17/140, P = 0.012). Seizure detection was greater for pEEG than ErEEG for the indication of evaluating for subclinical seizures after recent observed clinical seizures (14/41 [34.1%] versus 4/41 [9.8%], P = 0.002). There was no significant difference between modalities for seizure detection in patients undergoing evaluation of spells or mental status changes without previous observed seizures. Detection of seizures on pEEG was higher for recordings greater than 24 hours (8/46, 17%, P = 0.014) and 48 hours (19/26, 73%, P < 0.001) than recordings less than 24 hours (2/68, 3%). Seizure detection was higher with pEEG in comatose patients than ErEEG (17/51, 33% vs. 12/89, 13%; P = 0.009).

Conclusions: Increased value was demonstrated for pEEG over ErEEG in patients undergoing evaluation after observed recent clinical seizures and for coma. No significant difference was found between ErEEG and pEEG for seizure detection in the relatively small subgroups of patients with mental status changes other than coma and without preceding seizure or spells.

*The Ohio State University Wexner Medical Center, Columbus, Ohio, U.S.A.;

Mayo Clinic, Rochester, Minnesota, U.S.A.;

Emory University, Atlanta, Georgia, U.S.A.; and

§University of Toledo, Toledo, Ohio, U.S.A.

Address correspondence and reprint requests to Jaysingh Singh, MD, The Ohio State University Wexner Medical Center, 395 W, 12th Avenue, 7th Floor, Columbus, OH 43210, U.S.A.; e-mail:

J. Britton is a coinvestigator in clinical trials for GW Pharma and Grifols Pharmaceuticals. J. Singh, A. Alwaki, and P. Singh have no disclosures.

J. Singh and J. Britton had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: J. Singh and J. Britton. Data acquisition: J. Singh and A. Alwaki. Analysis or interpretation of data: All authors. Drafting of the manuscript and Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: P. Singh.

© 2019 by the American Clinical Neurophysiology Society