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Continuous electroencephalography in the medical intensive care unit*

Oddo, Mauro MD; Carrera, Emmanuel MD; Claassen, Jan MD; Mayer, Stephan A. MD; Hirsch, Lawrence J. MD

doi: 10.1097/CCM.0b013e3181a00604
Neurologic Critical Care

Objectives: To examine predictors and the prognostic value of electrographic seizures (ESZs) and periodic epileptiform discharges (PEDs) in medical intensive care unit (MICU) patients without a primary acute neurologic condition.

Design: Retrospective study.

Setting: MICU in a university hospital.

Patients: A total of 201 consecutive patients admitted to the MICU between July 2004 and January 2007 without known acute neurologic injury and who underwent continuous electroencephalography monitoring (cEEG) for investigation of possible seizures or changes in mental status.

Intervention: None.

Measurements and Main Results: Median time from intensive care unit (ICU) admission to cEEG was 1 day (interquartile range 1–4). The majority of patients (60%) had sepsis as the primary admission diagnosis and 48% were comatose at the time of cEEG. Ten percent (n = 21) of patients had ESZs, 17% (n = 34) had PEDs, 5% (n = 10) had both, and 22% (n = 45) had either ESZs or PEDs. Seizures during cEEG were purely electrographic (no detectable clinical correlate) in the majority (67%) of patients. Patients with sepsis had a higher rate of ESZs or PEDs than those without sepsis (32% vs. 9%, p < 0.001). On multivariable analysis, sepsis at ICU admission was the only significant predictor of ESZs or PEDs (odds ratio 4.6, 95% confidence interval 1.9–12.7, p = 0.002). After controlling for age, coma, and organ dysfunction, the presence of ESZs or PEDs was associated with death or severe disability at hospital discharge (89% with ESZs or PEDs, vs. 39% if not; odds ratio 19.1, 95% confidence interval 6.3–74.6, p < 0.001).

Conclusion: In this retrospective study of MICU patients monitored with cEEG, ESZs and PEDs were frequent, predominantly in patients with sepsis. Seizures were mainly nonconvulsive. Both seizures and periodic discharges were associated with poor outcome. Prospective studies are warranted to determine more precisely the frequency and clinical impact of nonconvulsive seizures and periodic discharges, particularly in septic patients.

From the Department of Neurology, Division of Critical Care (MO, EC, JC, SAM) and Comprehensive Epilepsy Center (JC, LJH), Neurological Institute, Columbia University Medical Center, New York, New York.

Supported, in part, by Research Grants from the SICPA Foundation, Lausanne, Switzerland (to MO and EC) and the Swiss National Science Foundation, Grant PBLAB-119620 (to EC).

This study was conducted at the Comprehensive Epilepsy Center, Neurological Institute, Columbia University Medical Center, New York, New York.

The authors have not disclosed any potential conflicts of interest.

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© 2009 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins