Efficacy of Ceeg for Management of Altered Mental Status in the Neurosurgical ICU

Introduction: The purpose of this study was to evaluate the efficacy and utility of continuous electroencephalograms (cEEGs) in detecting subclinical seizures (SCSs) in patients with unexplained altered mental status (AMS) in the neurosurgical intensive care unit (ICU) and demonstrate how they affect patient management and outcomes. We hypothesize that the diagnosis of a SCS on cEEG is not impactful on patient outcomes.

Methods: This was a retrospective chart review of 100 patients admitted to the neurosurgical ICU between 2015-2020 who underwent cEEG for workup of unexplained AMS. Patient outcomes were classified as positive, neutral, or negative. We analyzed the incidence of SCSs on cEEG and their association with patient outcomes with chi-square analysis and relative risk.

Results: Median age was 62 years and 43% were female. 16% of patients had a known or newly diagnosed brain tumor. 22 patients went on to have positive outcomes (discharged), 6 had neutral outcomes (transfer of care), and 72 had negative outcomes (death). SCSs were detected in 16 patients, of which 13 had negative outcomes, 2 had positive outcomes, and 1 had a neutral outcome. The association between SCS and treatment outcome was not statistically signficant (p = 0.36). Relative risk was 1.16 (CI 0.88 – 1.52, p = 0.26), indicating that patients who were diagnosed with and treated for a SCS did not have a statistically decreased risk of negative outcome (death).

Conclusion : We demonstrated a lower incidence of subclinical seizures than reported in the literature. cEEGs performed in the neurosurgical ICU to determine the etiology of AMS in the absence of clinically evident seizures did not yield an improvement in patient outcomes. In some patients, cEEG monitoring delayed necessary neurosurgical intervention. Therefore, EEG studies should only be considered after all other explanations for AMS have been ruled out and should not delay further neurosurgical interventions.