Ictal electroencephalographic characteristics during electroconvulsive therapy: a review of determination and clinical relevance.

OBJECTIVE: The usefulness of electroencephalogram (EEG) during electroconvulsive therapy (ECT) is not limited to the duration of seizure. The use of studying its characteristics has gained attention among specialized ECT researchers. This review attempts to put the literature in this area of ictal EEG in ECT into a practical perspective.
METHODS: A systematic database search using MEDLINE and EMBASE was performed using the keywords ECT and ictal EEG.
RESULTS: Manual, linear, and nonlinear methods have been used to analyze EEG obtained during ECT. Most studies have used spectral or linear methods of analysis. Studies using nonlinear have been sparse. There are 4 overlapping practical applications of analysis of EEG during ECT. First, EEG can discriminate between electrode positions and more controversially different stimulus doses. Second, EEG can predict treatment response. Postictal suppression is the measure most studied from all vantage points. Nonlinear approaches to determine EEG predictors hold promise. Third, changes in the EEG across ECT sessions may indicate threshold changes and aids more optimum dosimetry. Fourth, EEG characteristics have been incorporated into ECT clinical algorithms, but this still remains controversial, and there is a paucity of studies in this area.
CONCLUSIONS: The use of ictal EEG extends beyond determining the seizure length. The study of ictal EEG has certain practical uses, which could help individualize ECT treatment if applied in routine ECT practice.