Tardive seizure after electroconvulsive therapy: Prevalence and associated factors

Tardive seizure refers to a spontaneous seizure, which occurs after electroconvulsive therapy (ECT). It is a rare and poorly understood phenomenon that can lead to other serious consequences such as status epilepticus. Risk factors may be associated, and its management is by no means consensual. However, tardive seizure remains little explored in the absence of feedback and data sharing. The purpose of this study was to report the prevalence of late-onset seizures following ECT during the acute phase of treatment at the stimulation unit of Razi Hospital during its seven years of activity and to identify variables associated with this adverse event.

This is a descriptive and retrospective study that was carried out at the ECT unit of Razi Hospital, Tunisia, based on the medical records of patients treated with ECT between December 2015 and September 2023. Every recorded ECT session during the initial course of treatment with available EEG tracings was included in the study. Maintenance ECT sessions, undocumented sessions, those without clinical observations, and/or those without EEG tracings were all excluded. A tardive seizure was retained according to criteria that included both recorded motor manifestations such as "motor jerks" or "generalized tonic-clonic seizures" which began spontaneously after ECT and the resumption of a state of consciousness concurrent with an equivocal EEG tracing.

A total of 162 patients received at least one course of ECT during the research period. Ultimately, we included 1931 well documented sessions that were completed for 157 patients in all. Of the 157 patients, seven had experienced at least one late seizure after receiving ECT, accounting for 4.45% of patients. Among the 1931 sessions, 11 late seizures were noted. The prevalence of tardive seizures in our series was 0.57%. Several factors have been associated to the onset of a tardive seizure, including being a male, the presence of a neurological lesion, treatment that lowers the epileptogenic threshold, anesthesia with etomidate, stimulation charge near seizure threshold or maximum electrical load, prolonged induced seizure, and poor post-ictal suppression on the induced seizure tracing.

Despite the dearth of information, tardive seizure following ECT is considered to be a rare event. Risk factor management would be the first action to be taken to prevent such an event.