The Longitudinal Effects of Electroconvulsive Therapy on Ictal Interhemispheric Coherence and Its Associations With Treatment Outcome: A Naturalistic Cohort Study

Exploring New Electroencephalogram Parameters in Electroconvulsive Therapy

OBJECTIVE

This pilot study aims to evaluate a novel metric based on the power spectrum of the EEG recordings from ECT-induced seizures-its association to volume changes in the hippocampus after ECT and improvement in depression rating scores.

METHODS

Depressed patients treated with ECT underwent brain magnetic resonance imaging before and after treatment and the EEG from each seizure was recorded (N = 29). Hippocampal volume changes and EEG parameters were recorded in addition to clinician-rated and self-reported measures of depressive symptoms. The slope of the power law in the power spectral density of the EEG was calculated. Multivariate linear models relating seizure parameters to volume change or clinical outcome were systematically and successively simplified. The best models were selected according to Akaike information criterion.

RESULTS

The slope of the power law was steeper in the right than the left hemisphere (P < 0.001). Electroencephalogram measures were included in the best models of volume change for both hippocampi as well as in the models explaining clinical outcome ( P = 0.014, P = 0.004).

CONCLUSIONS

In this pilot study, novel EEG measures were explored and contributed in models explaining the variation in volume change in the hippocampus and in clinical outcome after ECT.

What Can We Tell About the Effect of Electroconvulsive Therapy on the Human Hippocampus?

Electroconvulsive therapy (ECT) is the most effective antidepressant treatment, although its mechanisms of action remain unclear. Since 2010, several structural magnetic resonance imaging studies based on a neuroplastic hypothesis have consistently reported increases in the hippocampal volume following ECT. Moreover, volume increases in the human dentate gyrus, where neurogenesis occurs, have also been reported. These results are in line with the preclinical findings of ECT-induced neuroplastic changes, including neurogenesis, gliogenesis, synaptogenesis, and angiogenesis, in rodents and nonhuman primates. Despite this robust evidence of an effect of ECT on hippocampal plasticity, the clinical relevance of these human hippocampal changes continues to be questioned. This narrative review summarizes recent findings regarding ECT-induced hippocampal volume changes. Furthermore, this review also discusses methodological considerations and future directions in this field.

Ictal Electroencephalogram Visual Pattern Recognition of Seizure Adequacy During Electroconvulsive Therapy Treatment: A Step-by-Step Approach

Background

The NEURON (Neuropsychiatry and Neuromodulation Unit) electroconvulsive therapy electroencephalogram (ECT-EEG) Algorithmic Rating Scale (NEARS) is a step-by-step approach to ictal electroencephalogram visual pattern recognition of seizure adequacy based on recruitment, amplitude, symmetry, duration and degree of post-ictal suppression. The objectives of this clinical audit were to determine the degree of agreement on the NEARS operational criteria between two neuropsychiatrists, the reliability of electroconvulsive therapy practitioners' administration of NEARS during ECT procedures and the correlation of NEARS scores with Clinical Global Impression scale scores after each ECT treatment session.

Methods

Systematic random sampling was conducted. Even numbers of ictal tracings were selected for analysis from the total samples collected over 8 consecutive days of ECT overseen by a total of eight different ECT practitioners. Cohen's kappa coefficient was used to measure the inter-rater reliability of the two neuropsychiatrists and determine the level of agreement between NEARS scores and those of the ECT practitioners. The correlation using NEARS scores and post-ECT Clinical Global Impression scores was measured with Spearman's test. The significance level was set at P < 0.05.

Results

Cohen's kappa showed perfect agreement between the two neuropsychiatrists, at κ = 1.00 (SE = 0.001; P < 0.001), and strong agreement between NEARS scores of overall seizure adequacy and the scores interpreted by the ECT practitioners, at κ = 0.83 (95% CI: 0.66, 0.99; P < 0.001). Spearman's test showed a weak negative association between NEARS scores and post-ECT Clinical Global Impression scores (r = -0.018; P = 0.900).

Conclusion

NEARS may facilitate a brief, objectively reliable and practical assessment of ictal electroencephalogram quality. The scale is readily applicable by any trained ECT practitioner during an ongoing ECT procedure, especially when a prompt treatment decision is required.

An Observational Retrospective Study Investigating Changes in Seizure Adequacy Parameters of Electroconvulsive Therapy and Their Relationships to Clinical Outcome in Schizophrenia and Schizoaffective Disorder

The aim of the current study was to investigate a possible relationship between electroconvulsive therapy (ECT) seizure adequacy parameters and clinical outcome as well as differences between ECT responders and nonresponders in terms of ECT seizure parameters in patients diagnosed with schizophrenia and schizoaffective disorder. First and last ECT records data, sociodemographic variables, and baseline and post ECT Positive and Negative Syndrome Scale scores were obtained. Maximum sustained power was higher in last ECT in favor of responders while peak heart rate was higher in ECT nonresponders than responders in first ECT. Stimulus doses were higher in last ECT than in the first ECT in both groups. No predictor variable was observed among baseline ECT seizure parameters for clinical improvement. Study was insufficient to yield a precise finding pointing a relationship between electrophysiological seizure parameters and clinical outcome in schizophrenia and schizoaffective disorder.

Using EEG to Predict Clinical Response to Electroconvulsive Therapy in Patients With Major Depression: A Comprehensive Review

Introduction: An important approach to improve the therapeutic effect of electroconvulsive therapy (ECT) may be to early characterize patients who are more likely to respond. Our objective was to explore whether baseline electroencephalography (EEG) settings before the beginning of ECT treatment can predict future clinical response to ECT in patients with depressive disorder. Methods: We conducted a systematic search in the MEDLINE, EMBASE, PsycINFO, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) databases to identify studies using EEG in adults with depressive disorder treated by ECT. To investigate the predictive value of baseline EEG on clinical outcomes of ECT, we extracted from the retrieved studies and qualitatively described the association between the baseline EEG markers characteristics and the rates of future responders and/or remitters to ECT. Results: The primary search yielded 2,531 potentially relevant citations, and 12 articles were selected according to inclusion criteria. Most of the studies were prospective studies with small sample size. Sociodemographic and clinical characteristics of patients, ECT settings, EEG settings, and outcomes were heterogeneous. Event-related potential (ERP) paradigms were used in three studies, polysomnography was used in three studies, and the six other studies used EEG to measure cerebral connectivity and activity. Conclusions: P300 amplitude, coherence, and connectivity measures were correlated with remission in patients with depression treated by ECT. Sleep EEG recordings seemed not to be correlated with remission after ECT. Further prospective studies with large sample size are needed to determine optimal EEG parameters associated with clinical response to ECT in depressive disorder. Systematic Review Registration: PROSPERO CRD42020181978.

The ictal EEG in ECT: A systematic review of the relationships between ictal features, ECT technique, seizure threshold and outcomes

OBJECTIVE

To provide guidance for ECT practitioners in utilising the ictal EEG to inform treatment decisions.

METHODS

A systematic review of studies examining the ictal EEG, treatment technique, seizure threshold and treatment outcomes was conducted. MEDLINE, EMBASE and PsycINFO databases were searched up to July 31, 2019. Studies were included if they examined the use of ECT in human subjects and compared an ictal EEG analysis (either quantitative or manually rated) with either: a) clinical outcomes, b) seizure threshold/threshold change, c) ECT dosing decisions, or d) different aspects of ECT technique (comparison of different electrode placements, pulse widths, waveforms, or dose/dose relative to seizure threshold).

RESULTS

A total of 853 studies were identified, with 44 meeting inclusion criteria. A qualitative review revealed ictal EEG indices have been linked to therapeutic outcome, though the strength of this relationship appears modest. Ictal EEG features are influenced by variations in ECT treatment technique. Serial ictal EEG monitoring can detect changes in seizure threshold across an ECT course for right unilateral brief and ultrabrief pulse ECT.

CONCLUSION

While there is some relationship between ictal EEG manifestation and treatment outcomes, the primary utility of ictal EEG monitoring during an ECT course may lie in the capacity to detect changes in seizure threshold and adjust dosing accordingly. Prospective validation of a dosing regime informed by serial ictal EEG monitoring is warranted.