THE ICTAL EEG AS A MARKER OF ADEQUATE STIMULUS-INTENSITY WITH UNILATERAL ECT

Relative stimulus intensity above seizure threshold has been shown to affect therapeutic outcome with unilateral ECT. The authors sought to explore whether a multivariate ictal EEG model! would permit ongoing c linical assessment of this parameter. Twenty-five depressed subjects w ere randomized to either barely (T) or moderately (2.5T) suprathreshol d ECT treatments. Seizures in 2.5T subjects had significantly greater ictal spectral amplitude and coherence, greater postictal suppression, and shorter latency until ictal slow-wave onset. A multivariate logis tic regression ictal EEG model distinguished between stimulus intensit y groups with 90% accuracy. Preliminary evidence suggests a relationsh ip between several ictal EEG indices and therapeutic outcome. A multiv ariate ictal EEG algorithm holds promise as a tool for clinical determ ination of adequate stimulus intensity with unilateral ECT.