Quantification of EEG reactivity in comatose patients

•Quantitative EEG features are used to classify reactive and non-reactive EEGs.•Probabilities based on quantitative EEG features reflect the degree of reactivity.•Quantitative methods may increase reproducibility and objectivity of EEG reactivity assessment.

ObjectiveEEG reactivity is an important predictor of outcome in comatose patients. However, visual analysis of reactivity is prone to subjectivity and may benefit from quantitative approaches.MethodsIn EEG segments recorded during reactivity testing in 59 comatose patients, 13 quantitative EEG parameters were used to compare the spectral characteristics of 1-minute segments before and after the onset of stimulation (spectral temporal symmetry). Reactivity was quantified with probability values estimated using combinations of these parameters. The accuracy of probability values as a reactivity classifier was evaluated against the consensus assessment of three expert clinical electroencephalographers using visual analysis.ResultsThe binary classifier assessing spectral temporal symmetry in four frequency bands (delta, theta, alpha and beta) showed best accuracy (Median AUC: 0.95) and was accompanied by substantial agreement with the individual opinion of experts (Gwet's AC1: 65-70%), at least as good as inter-expert agreement (AC1: 55%). Probability values also reflected the degree of reactivity, as measured by the inter-experts' agreement regarding reactivity for each individual case.ConclusionAutomated quantitative EEG approaches based on probabilistic description of spectral temporal symmetry reliably quantify EEG reactivity.SignificanceQuantitative EEG may be useful for evaluating reactivity in comatose patients, offering increased objectivity.