Prognostic value of EEG in post-anoxic coma after cardiac arrest.

The authors themselves studied 26 patients. The EEGs were classified in terms of increasing severity in 5 categories. Incorporating over 400 cases from the literature, the authors correlated the initial EEG findings with the clinical outcome following cardiac arrest. Grade I EEG findings (normal alpha with theta-delta activity) imply a very good prognosis. A complete remission can be expected in most cases. Grade II (dominant theta-delta activity with detectable normal alpha) and grade III (dominant theta-delta activity without detectable normal alpha) findings have no definite prognosis. Grade IV [low-voltage delta, possibly with short isoelectric intervals; dominant, monomorphic, non-reactive alpha-activity (alpha coma); periodic generalized phenomena (spikes, sharp waves, slow waves with very low background activity)] and grade V (very flat to isoelectric EEG) findings have a very serious prognosis.