Prognostic significance of episodic low amplitude or relatively isoelectric EEG patterns

Electroencephalograms demonstrating episodes of relative iso-electric activity in 14 comatose patients are divided into three patterns. The first, Type I, showed brief low amplitude or relatively iso-electric episodes intermixed with slow activity. The second, Type II, showed epileptogenic activity with episodes of relative iso-electricity. The third, Type III, showed burst suppression in which iso-electric intervals were of greater duration than periodic slow activity. All patients expired, indicating grave prognostic implications for all three patterns.