Unraveling the Importance of Seizure Duration in Electroconvulsive Therapy

Electroconvulsive therapy (ECT) has a long history as an effective treatment for a range of psychiatric conditions.While the precise mechanism of action of ECT remains uncertain, the induction of a therapeutic seizure is a necessary part of the treatment.A seizure in and of itself, however, is not sufficient for improvement because different electrical doses and electrode placements may result in clinically similar seizures but yield vastly different therapeutic outcomes.1 Thus, research over many decades has explored ECT-induced seizures, with the hopes of identifying properties of the therapeutic seizure that may be important for clinical effectiveness. 2 The simplest and most studied of these properties is the duration of the seizure either as observed clinically (via convulsive movements) or electrographically.It has been a long-held belief that short seizures may not be as clinically effective as longer ones, but there has been little empirical support for this clinical observation.Gillving and colleagues 3 explored this question in a large registry-based cohort study of Swedish patients with depression undergoing treatment with ECT.The findings provide evidence for the relative ineffectiveness of short (less than 20 seconds) initial seizures at relieving symptoms of depression.The authors used the Swedish National Quality Register for ECT, which covers the majority of ECT treatments performed in Sweden, to examine individuals with unipolar major depression who were receiving treatment with right unilateral ECT and who provided self-assessment of their depression using the Montgomery-Åsberg Depression Rating Scale (MADRS-S).3 The study focused on seizure duration, as measured by single-channel electroencephalography, at time of first treatment and its association with clinical depression response in univariate models and models adjusted for demographic and treatment parameters.The nationwide clinical database provided a large sample size of 6998 ECT recipients.Consistent with most other ECT studies, the present study had a population of predominantly female (60.4%) and older (mean [SD] age, 55.2 [18.6] years) patients, with 39.3% achieving remission from depression (based on MADRS-S scores) after a median (IQR) of 7 (6-9) ECT sessions.Both older age and psychotic depression were associated with higher odds of remission after ECT treatment, which is again consistent with findings from prior ECT literature.The concomitant use of anticonvulsant medications (including lamotrigine) or benzodiazepines was associated with lower odds of remission, while the use of antidepressants, lithium, or antipsychotics was not associated with differential odds of remission.In univariate and multivariate models, seizure duration of at least 20 seconds at the time of first treatment was associated with higher odds of remission than an initial seizure duration of less than 20 seconds, with an odds ratio of 2.17 (univariate) and 2.52 (multivariate) for seizure duration of 60 to 69 seconds vs less than 20 seconds.Overall, these results lend strong evidence to the notion that short seizures at the time of first ECT treatment portend a less favorable outcome than longer initial seizures.Generalizability of these findings is enhanced by the large sample size, the inclusion of multiple hospitals with independent clinical protocols, the use of ECT devices by different manufacturers, and the use of different anesthetic agents (propofol and thiopental) at different study sites.Caution is required, however, in extrapolating from findings at the time of first seizure to analysis of seizures in the overall ECT course.First, and most importantly, even among those with initial seizures of less than 20 seconds the remission rate from depression was 27.2%, which is much greater than that obtained by pharmacotherapy in patients with treatment resistance.As a result, a short seizure at the time of first treatment should not be a reason to discontinue ECT in patients for +