Continuous versus Routine Electroencephalography in the Intensive Care Unit: A Review of Current Evidence

Abstract

Background Electroencephalography has long been used to detect seizures in patients with disorders of consciousness. In recent years, there has been a drastically increased adoption of continuous EEG (cEEG) in the ICUs. Summary Despite the development of increasingly performant imaging techniques and several validated biomarkers, EEG remains central to clinicians in the intensive care unit, and is experiencing expanding indications. Not only does EEG allow seizure or status epilepticus detection, which in the ICU often present without clinical movements, but it is also central for the prognostic evaluation of comatose patients, especially after cardiac arrest, and for detecting delayed ischemia after subarachnoid hemorrhage. Around two decades ago, improvements of technical aspects of recording and storing EEG tracings have led into the era of continuous EEG (cEEG) and automated quantitative analysis (qEEG). Given resources necessary to record and interpret cEEG, this is still not available in every center and widespread recommendations to use continuous instead of routine EEG (typically lasting 20 minutes) are still a matter of debate. In light of recent literature and personal experience, this review offers a rationale to address this question. Key message As compared to repeated rEEG, cEEG in comatose patients does not seem to improve clinical prognosis to a relevant extent, despite allowing a more performant detection ictal events and consequent therapeutic modifications. The choice between cEEG and rEEG must therefore always be patient tailored.

The Role of Routine Electroencephalography in the Diagnosis of Seizures in Medical Intensive Care Units

“…This relatively low incidence is possibly due to the exclusion of patients with neurological crises or subtle status epilepticus and a limitation of seizure detection by rEEG. cEEG has been reported to be more effective at detecting epilepsy, particularly NCSE, than rEEG is [ 8 , 23 ]. Kamel et al used cEEG to monitor patients in medical and surgical ICUs (excluding patients with acute brain injury, consistent with the exclusion criteria of the present study) and identified ESz in 11% of the patients [ 5 ].…”

“…cEEG studies are also useful for the prognostic evaluation of comatose patients in ICUs [ 4 , 5 ]. cEEG is more effective at detecting NCSs and NCSE than rEEG is; however, cEEG is not associated with improved outcomes compared with those of repeated rEEG [ 6 , 7 , 8 ].…”