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Continuous Electroencephalography in the Critically Ill: Clinical and Continuous Electroencephalography Markers for Targeted Monitoring

Newey, Christopher R.*,†; Kinzy, Tyler G.; Punia, Vineet*; Hantus, Stephen*,†

Journal of Clinical Neurophysiology: July 2018 - Volume 35 - Issue 4 - p 325–331
doi: 10.1097/WNP.0000000000000475
Original Research

Purpose: Electrographic seizures detected by continuous electroencephalography (CEEG) in critically ill patients with altered mental status is becoming increasingly recognized. Data guiding the appropriate selection of patients to be monitored on CEEG are lacking. The aims of this article were to study the incidence of seizures in the critical care setting and to evaluate for clinical predictors to improve the efficiency of CEEG monitoring.

Methods: Retrospective review of the CEEG and clinical data on 1,123 consecutive patients who had continuous video EEG over a 24-month period.

Results: Seizures were recorded in 215 patients on CEEG monitoring (19.1%). In total, 89.3% of these seizures occurred without clinical signs. Patients who were in a coma were more likely to have EEG seizures (odds ratio, 3.64; 95% confidence interval, 2.23–5.95) compared with those awake. The incidence of seizures was overrepresented in patients with extra-axial tumors (41.9%), multiple sclerosis (35.7%), and intra-axial tumors (33.0%). Lateralized periodic discharges were predictive (odds ratio, 8.27; 95% confidence interval, 5.52–12.46) of seizure occurrence compared with those with no epileptiform patterns. Only generalized periodic discharges with triphasic morphology had no increased odds of seizure (odds ratio, 1.02; 95% confidence interval, 0.24–3.03). When present, electroencephalography seizures were detected within 24 hours in 92% of monitored patients.

Conclusions: Continuous electroencephalography monitoring in the critical care setting demonstrates a linear increase in seizure incidence with declining mental status. Recognizing clinical conditions and electroencephalography markings may help in the appropriate selection of critically ill patients for CEEG monitoring.

*Cleveland Clinic, Epilepsy Center, Neurological Institute, Cleveland, Ohio, U.S.A.;

Cleveland Clinic, Cerebrovascular Center, Neurological Institute, Cleveland, Ohio, U.S.A.; and

Cleveland Clinic, Quantitative Health Sciences, Cleveland, Ohio, U.S.A.

Address correspondence and reprint requests to Christopher R. Newey, DO, MS, Department of Neurology, Cerebrovascular and Epilepsy Centers, Neurological Institute, 9500 Euclid Avenue, Cleveland, OH 44195-5245, U.S.A.; e-mail:

C. R. Newey has served on speaker's bureau for BARD Medical. S. Hantus has served as a consultant and on advisory boards for UCB Pharma. The remaining authors have no funding or conflicts of interest to disclose.

© 2018 by the American Clinical Neurophysiology Society