Generalization, duration, and low-frequency electroencephalographic persistence of bilateral electroconvulsive therapy seizure

Measurements were made at the beginning and end of a course of bifrontotemporal brief-pulse ECT for 28 males to both determine how well seizure generalization is maintained along the course of electroconvulsive therapy (ECT) and examine correspondence between low-frequency EEG activity and other seizure durations. Durations of spike electroencephalographic (EEG) paroxysmal activity, heart rate elevation, and tonic-clonic activity decreased about 30% along the course, p< 0.0001, yet correlated highly at both times, r = 0.69 to 0.88, p< 0.0005, as did their changes; these correlations demonstrate high-seizure generalization and its maintenance. EEG low-frequency persistence, the difference between total and spike EEG paroxysmal durations, doubled along the course (p = 0.041), but showed no association with any other seizure duration measure. This absence of association suggests that low-frequency activity and other seizure duration measures describe separate phenomena and should be expressed separately, rather than combined as the (traditional) total EEG paroxysmal duration.