Prediction of the utility of a switch from unilateral to bilateral ECT in the elderly using treatment 2 ictal EEG indices

Background: The choice of whether to administer nondominant unilateral (UL) or bilateral (BL) ECT remains controversial. Methods: A study in which mod erately suprathreshold UL nonresponders at treatment 6 were randomized to U L or BL ECT offered the opportunity to explore whether ictal EEG indices at treatment 2 might predict response to UL ECT, and also which UL ECT nonres ponders are likely to respond to BL ECT. Results: We found that less postic tal suppression in response to the second UL ECT stimulus was predictive of a poorer subsequent therapeutic response to UL ECT, but of a better therap eutic response if switched to BL ECT. A multivariate ictal EEG model was de veloped that had a significant capacity to differentiate those who will res pond to UL ECT versus those who will not respond to UL ECT, but who will be therapeutic responders when switched to BL ECT. Conclusions: This study ra ises the possibility that ictal EEG indices at treatment 2 may identify sit uations when UL ECT is physiologically and therapeutically inadequate, and when BL ECT is likely to be more effective. The determination of whether su ch predictive physiologic models are of clinical utility for the prediction of outcome awaits further study.