Quiescence During Burst Suppression and after ECT Seizures Compared:

 Out on PubMed, from investigators at Washington University in St. Louis and elsewhere, is this paper:

Quiescence during burst suppression and postictal generalized EEG suppression are distinct patterns of activity.

Kafashan M, Brian Hickman L, Labonte AK, Huels ER, Maybrier H, Guay CS, Subramanian S, Farber NB, Ching S, Hogan RE, Kelz MB, Avidan MS, Mashour GA, Palanca BJA.Clin Neurophysiol. 2022 Jul 30;142:125-132. doi: 10.1016/j.clinph.2022.07.493. Online ahead of print.PMID: 36030576

The abstract is copied below:

Objective: Periods of low-amplitude electroencephalographic (EEG) signal (quiescence) are present during both anesthetic-induced burst suppression (BS) and postictal generalized electroencephalographic suppression (PGES). PGES following generalized seizures induced by electroconvulsive therapy (ECT) has been previously linked to antidepressant response. The commonality of quiescence during both BS and PGES motivated trials to recapitulate the antidepressant effects of ECT using high doses of anesthetics. However, there have been no direct electrographic comparisons of these quiescent periods to address whether these are distinct entities.

Methods: We compared periods of EEG quiescence recorded from two human studies: BS induced in 29 healthy adult volunteers by isoflurane general anesthesia and PGES in 11 patients undergoing right unilateral ECT for treatment-resistant depression. An automated algorithm allowed detection of EEG quiescence based on a 10-microvolt amplitude threshold. Spatial, spectral, and temporal analyses compared quiescent epochs during BS and PGES.

Results: The median (interquartile range) voltage for quiescent periods during PGES was greater than during BS (1.81 (0.22) microvolts vs 1.22 (0.33) microvolts, p < 0.001). Relative power was greater for quiescence during PGES than BS for the 1-4 Hz delta band (p < 0.001), at the expense of power in the theta (4-8 Hz, p < 0.001), beta (13-30 Hz, p = 0.04) and gamma (30-70 Hz, p = 0.006) frequency bands. Topographic analyses revealed that amplitude across the scalp was consistently higher for quiescent periods during PGES than BS, whose voltage was within the noise floor.

Conclusions: Quiescent epochs during PGES and BS have distinct patterns of EEG signals across voltage, frequency, and spatial domains.

Significance: Quiescent epochs during PGES and BS, important neurophysiological markers for clinical outcomes, are shown to have distinct voltage and frequency characteristics.

Keywords: Anesthesia; Burst suppression; Electroconvulsive therapy; Electroencephalography; Major depressive disorder; Postictal generalized electroencephalographic suppression; Seizures.

The article is here.

And from the text:

I feared this article would be technical, boring and clinically irrelevant. I was only correct about the technical part; this article is actually fascinating and potentially very clinically relevant! It is clearly written and beautifully presented.

Postictal suppression in ECT is important, and is one of the few EEG signatures that has been reliably linked to antidepressant outcomes. Here, contrasted with the quiescence in burst suppression, it is suggested as a possible key to understanding neural physiology underlying the mechanism of action of ECT.

All followers of the EEG in ECT literature will want to fully and carefully read this paper, ~25 minutes.