Predicting outcome in postanoxic coma: are ten EEG electrodes enough?

Introduction:Increasing evidence supports that early EEGrecordings reliably contribute to outcome prediction incomatose patients with postanoxic encephalopathy. Aspostanoxic encephalopathy typically results in generalized EEGabnormalities, spatial resolution of a small number ofelectrodes is likely sufficient, which will reduce set-up time.Here, the authors compare a reduced and a 21-channel EEG foroutcome prediction.Methods:EEG recordings from 142 prospectively collectedpatients with postanoxic encephalopathy were reassessed bytwo independent reviewers using a reduced (10 electrodes)bipolar montage. Classification and prognostic accuracy werecompared with the full (21 electrodes) montage. The fullmontage consensus was considered Gold Standard.Results:Sixty-seven patients (47%) had good outcome. Theagreement between the individual reviewers using the reducedmontage and the Gold Standard score was good (k¼0.75–0.79). The interobserver agreement was not affected byreducing the number of electrodes (k¼0.78 for the reducedmontage vs. 0.71 for the full montage). An isoelectric, low-voltage, or burst-suppression with identical bursts pattern at24 hours invariably predicted poor outcome in both montages,with similar prognostic accuracy. A diffusely slowed or normalEEG pattern at 12 hours was associated with good outcome inboth montages.Conclusions:Reducing the number of electrodes from 21 to 10does not affect EEG classification or prognostic accuracy inpatients with postanoxic com