Postictal Suppression on EEG: New Study
Out on PubMed, from researchers in California, Missouri, and Michigan, is this study:
Postictal generalized electroencephalographic suppression following electroconvulsive therapy: Temporal characteristics and impact of anesthetic regimen.
Objective: Postictal generalized electroencephalographic suppression (PGES) has been defined as electroencephalographic (EEG) activity of less than 10 microvolts following a generalized seizure. PGES is associated with an increased risk of sudden unexplained death in epilepsy, as well as treatment efficacy of electroconvulsive therapy (ECT). We investigated the impact of anesthetic on PGES expression and temporal characteristics.
Methods: We recorded postictal EEG in 50 ECT sessions in 11 patients with treatment resistant depression (ClinicalTrials.gov NCT02761330). For each participant, repeated sessions included either ketamine or etomidate general anesthesia during ECT. An automated algorithm was employed to detect PGES within 5 minutes after seizure termination.
Results: PGES was detected in 31/50 recordings, with intermittent epochs recurring up to five minutes after seizure termination. PGES total duration was greater following ketamine than etomidate anesthesia (p = 0.04). PGES expression declined loglinearly as a function of time (r = -0.89, p < 10-4). EEG amplitude during PGES did not vary linearly with time.
Conclusions: PGES can occur intermittently for several minutes following seizure termination. Anesthetic effects should be considered when correlating PGES duration to clinical outcomes.
Significance: Prolonged EEG monitoring several minutes following seizure termination may be necessary to fully evaluate the presence and total duration of PGES.
Keywords: Electroconvulsive therapy (ECT); Major depressive disorder; Postictal generalized electroencephalographic suppression; Seizure; Sudden unexplained death in epilepsy.
Clin Neurophysiol. 2021 Jan 28;132(4):977-983. doi: 10.1016/j.clinph.2020.12.018. Online ahead of print.PMID: 33652270
The abstract is copied below:
Objective: Postictal generalized electroencephalographic suppression (PGES) has been defined as electroencephalographic (EEG) activity of less than 10 microvolts following a generalized seizure. PGES is associated with an increased risk of sudden unexplained death in epilepsy, as well as treatment efficacy of electroconvulsive therapy (ECT). We investigated the impact of anesthetic on PGES expression and temporal characteristics.
Methods: We recorded postictal EEG in 50 ECT sessions in 11 patients with treatment resistant depression (ClinicalTrials.gov NCT02761330). For each participant, repeated sessions included either ketamine or etomidate general anesthesia during ECT. An automated algorithm was employed to detect PGES within 5 minutes after seizure termination.
Results: PGES was detected in 31/50 recordings, with intermittent epochs recurring up to five minutes after seizure termination. PGES total duration was greater following ketamine than etomidate anesthesia (p = 0.04). PGES expression declined loglinearly as a function of time (r = -0.89, p < 10-4). EEG amplitude during PGES did not vary linearly with time.
Conclusions: PGES can occur intermittently for several minutes following seizure termination. Anesthetic effects should be considered when correlating PGES duration to clinical outcomes.
Significance: Prolonged EEG monitoring several minutes following seizure termination may be necessary to fully evaluate the presence and total duration of PGES.
Keywords: Electroconvulsive therapy (ECT); Major depressive disorder; Postictal generalized electroencephalographic suppression; Seizure; Sudden unexplained death in epilepsy.
and a figure:
This is a study with complex EEG analyses of postictal generalized electroencephalographic suppression (PGES) episodes in 11 patients who had a total of 50 ECT sessions with RUL-UBP ECT; 64 recorded channels are reduced to 18. The two findings are 1) that the episodes can occur up to 5 minutes postictal and 2) that PGES total duration was greater with ketamine than with etomidate. The authors assert that their method is far superior to the postictal suppression index (PSI) of the Thymatron. IMO, however, the relevance of their findings to clinical ECT is not at all clear. While I am not a neurophysiologist, I am unconvinced by the above figure and much of the rest of the paper. No need to run the EEG for another 5 minutes...
In clinical ECT, the most important EEG function is to show that the seizure has ended; the PSI is icing on the cake, possibly indicating the strength of elicitation of anticonvulsant brain mechanisms.
For neurophysiologists, this paper will be fascinating reading (~30 minutes), for the rest of us, the abstract should suffice.
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