Abstract
Highly malignant electroencephalogram (EEG) patterns (including suppressed background and burst suppression) refer to a poor neurological outcome in cardiac arrest patients, but some of those patients may show a good neurological outcome. This is the first report that details the reason for their uncommon survival despite highly malignant EEG patterns after cardiac arrest. The brain cortical activities in very elderly patients (who are vulnerable to the usual sedative doses) showed a suppressed background and burst suppression but resulting in a good neurological outcome. The mean suppression rates from their EEGs were 100% and 68.4%, respectively, and a normal pattern was completely restored after the sedatives had affected their brain waves for 12 hours. It was speculated that sedatives given at an ordinary dose may negatively affect the brain's cortical activity in elderly patients who demonstrate a good neurological outcome. When appropriate doses of sedatives are used, highly malignant EEG patterns in very elderly patients should be carefully interpreted for early neuroprognostication.