Electromyographic reactivity measured with scalp-EEG contributes to prognostication after cardiac arrest

To assess whether stimulus-induced modifications of electromyographic activity observed on scalp EEG have a prognostic value in comatose patients after cardiac arrest. 184 adult patients from a multi-centric prospective register who underwent an early EEG after cardiac arrest were included. Auditory and somatosensory stimulation was performed during EEG-recording. EEG reactivity (EEG-R) and EMG reactivity (EMG-R) were retrospectively assessed visually by board-certified electroencephalographers, and compared with clinical outcome (cerebral performance category, CPC) at three months. A favorable functional outcome was defined as CPC 1–2, an unfavorable outcome as CPC 3–5. Both EEG-R and EMG-R were predictors for good outcome (EEG-R accuracy 72% (95%-CI 66–79), sensitivity 86% (78–93), specificity 60% (50–69); EMG-R accuracy 65% (58–72), sensitivity 61% (51–75), specificity 69% (60–78)). When reactivity was defined as EEG-R and/or EMG-R, the accuracy was 73% (67–70), the sensitivity 94% (90–99), and the specificity 53% (43–63). Taking EMG into account when assessing reactivity of EEG seems to reduce false negative predictions for identifying patients with favorable outcome after cardiac arrest.