Original ArticlesQuantitative EEG During Seizures Induced by Electroconvulsive Therapy: Relations to Treatment Modality and Clinical Features. II. Topographic AnalysesLuber, Bruce Ph.D; Nobler, Mitchell S. M.D; Moeller, James R. Ph.D; Katzman, Gary P. B.A; Prudic, Joan M.D; Devanand, D. P. M.D*; Dichter, Gabriel S. B.A; Sackeim, Harold A. Ph.D†Author Information Department of Biological Psychiatry, New York State Psychiatric Institute, New York; and Departments of Psychiatry, *Neurology, and †Radiology, College of Physicians and Surgeons of Columbia University, New York, New York, U.S.A. Received March 16, 1999; accepted May 6, 1999. Address correspondence and reprint requests to Dr. H. A. Sackeim, Department of Biological Psychiatry, New York State Psychiatric Institute, 1051 Riverside Dr., New York, NY 10032, U.S.A. The Journal of ECT: September 2000 - Volume 16 - Issue 3 - p 229-243 Buy Abstract This study tested three alternative theories of the mechanisms of therapeutic action of electroconvulsive therapy (ECT). The theories differed in predictions about the global and topographic effects of effective and ineffective forms of ECT on electroencephalogram (EEG) seizure expression. At the second treatment, 19-lead EEG recordings were obtained in 57 depressed patients randomized to conditions that differed in ECT electrode placement and stimulus dosage. Power in the delta frequency band was quantified during the seizure and analyzed with traditional multivariate methods and the Scaled Subprofile Model. Electrical dosage of the ECT stimulus had a powerful effect on ictal global delta power and, more so, than electrode placement. Greater ictal global delta power was associated with superior therapeutic outcome, but the magnitude of this effect was small. Effective forms of ECT resulted in a topography where delta power was accentuated in prefrontal EEG sites. High dosage right unilateral ECT also resulted in stronger asymmetry in prefrontal regions than the ineffective, low dosage right unilateral ECT. Greater bilateral generalization of seizure expression does not appear to be a prerequisite for therapeutic effects. Instead, more intense seizure expression in prefrontal regions may be critical for efficacy. © 2000 Lippincott Williams & Wilkins, Inc.