Abstracts

Rationale: Electroencephalography (EEG) allows monitoring of generalized seizures induced during electroconvulsive therapy (ECT). Scalp EEG recordings show different phases of electroencephalographic ictal activity during ECT seizures, documenting a pattern of seizures that may vary on both an intra-subject and inter-subject level. In this report, we used 64-electrode high-density EEG recording to detect topographic electroencephalographic changes not typically evident with conventional limited montage commonly used during ECT. Methods: EEG recordings were acquired from four participants during right unilateral ECT sessions for treatment-resistant depression for a total of 19 seizures in the analysis. Using previously proposed staging criteria, the ictal EEGs were interpreted by an expert reviewer blinded to study treatment parameters. Results: High-density EEG recordings of all 19 seizures showed generalized, high-amplitude, central-positive sharp waves. The central-positive sharp waves emerged at the beginning of Phase III (polyspike and slow wave activity). The general pattern of the central-positive sharp waves evolved from 4.0 Hz to 1.5 Hz in frequency and from 500 to 300 microvolts in amplitude. Elaborating on previously described phases of ECT-induced electrographic seizures, we describe variability in morphology at seizure termination.  Central-positive sharp waves showed a mean duration of 81 seconds, median duration of 51 seconds, and range of 22-203 seconds. These complexes persisted until seizure termination in 11 seizures, whereas the remaining eight seizures persisted after resolution of central-positive sharp waves.  Duration of  persistent seizures after the central positive sharp waves in these 8 seizures showed a mean of 26 seconds, median of 24 seconds, and range from 3-62 seconds. Conclusions: We detected generalized, high-amplitude, central-positive sharp wave complexes at the beginning of Phase III in all 19 seizures. These complexes represent a novel finding  for ECT-induced seizures, and may allow for a better understanding of the pathophysiology of generalized tonic-clonic seizures. Funding: The study was funded by the James S. McDonnell Foundation (US).