VARIATION OF ICTAL ELECTROENCEPHALOGRAPHIC REGULARITY WITH LOW-DOSE, MODERATE-DOSE, AND HIGH-DOSE STIMULI DURING RIGHT UNILATERAL ELECTROCONVULSIVE-THERAPY

Background: Previous work has demonstrated changes in electroencephalo graphic (EEC) ictal morphology during electroconvulsive therapy (ECT) as stimulus intensify is increased from barely suprathreshold to moder ately suprathreshold Our study reports on the reactivity of seizure re gularity ratings in 11 subjects receiving right unilateral (RUL) ECT a s the stimulus is varied over a wider range of intensities from low to medium, then high dose. Methods: The stimulus intensity of all 11 sub jects was first increased from barely suprathreshold to moderately sup rathreshold, and then randomized to either stay at a moderately suprat hreshold dose or increase to a high dose. The regularity of the EEG ic tal discharge was visually measured on a seven-point scale. Results: W e found that seizure regularity increases as the stimulus intensity mo ves from the barely suprathreshold to the moderately suprathreshold do sage, but did not increase further when the stimulus increased to a hi gh dose, Conclusions: These results suggest that EEG regularity is unl ikely to distinguish moderately suprathreshold from markedly suprathre shold stimuli during RUL ECT. (C) 1998 Society of Biological Psychiatr y.