The role of the electroencephalogram and evoked potentials after cardiac arrest

Purpose of reviewIn comatose cardiac arrest survivors, the electroencephalogram (EEG) is the most widely used test to assess the severity of hypoxic-ischemic brain injury (HIBI) and guide antiseizure treatment. However, a wide variety of EEG patterns are described in literature. Moreover, the value of postarrest seizure treatment is uncertain. Absent N20 waves of short-latency somatosensory-evoked potentials (SSEPs) are a specific predictor of irreversible HIBI. However, the prognostic significance of the N20 amplitude is less known.Recent findingsThe increasing adoption of standardized EEG pattern classification identified suppression and burst-suppression as 'highly-malignant' EEG patterns, accurately predicting irreversible HIBI. Conversely, continuous normal-voltage EEG is a reliable predictor of recovery from postarrest coma. A recent trial on EEG-guided antiseizure treatment in HIBI was neutral but suggested potential benefits in specific subgroups. A prognostic approach based on the amplitude rather than on the presence/absence of the N20 SSEP wave recently showed greater sensitivity for poor outcome prediction and added potential for predicting recovery.Standardized EEG terminology and quantitative approach to SSEP are promising for improving the neuroprognostic accuracy of these tests. Further research is needed to identify the potential benefits of antiseizure treatment after cardiac arrest.

Automated summary

In comatose cardiac arrest survivors, the EEG is commonly used to assess the severity of brain injury and guide antiseizure treatment. However, there are various EEG patterns described in literature and the value of postarrest seizure treatment is uncertain. Recent findings suggest that certain EEG patterns can accurately predict irreversible brain injury, while continuous normal-voltage EEG indicates potential recovery. Additionally, a prognostic approach based on SSEP amplitude shows promise for outcome prediction.