Authors :
Chetan Nayak, MD, PhD – Washington University School of Medicine; Emma Huels, BS – Anesthesiology – University of Michigan; MohammadMehdi Kafashan, PhD – Anaesthesiology – Washington University School of Medicine; Fabio Nascimento E Silva, MD – Assistant Professor, Neurology, Washinton University School of Medicine; Ben Julian Palanca, MD PhD – Anaesthesiology – Washington University School of Medicine; Robert Hogan, MD – Director, Epilepsy Center, Neurology, Washington University School of Medicine
This is a Late Breaking abstractRationale: Impaired consciousness associated with seizures is an important clinical issue. Due to the associated sudden change in awareness of surroundings and inability to control behavior, disruptions in consciousness during seizures are a major source of morbidity and mortality for patients. Despite the clinical importance of consciousness changes during seizures, objective clinical study of changes in consciousness has been limited by numerous factors, including involvement of different brain regions within specific seizure types, unpredictable occurrence, and wide variability of severity of seizures.
Patients undergoing electroconvulsive therapy (ECT) provide a population with minimal associated motion during seizures, predictable seizure timing, and homogenous seizure type. We have previously reported on the consistency of central positive complexes (CPCs) that arise during these generalized seizures (Hogan, 2019). In this study, we objectively evaluate subjects undergoing ECT for depression, quantifying the duration of CPCs and the time of recovery of responsiveness._x000D_
Methods: This investigation is a secondary analysis of data collected from Reconstructing Consciousness and Cognition Phase 2 study (ClinicalTrials.gov NCT02761330). We recorded high-density 64-electrode EEG recordings to provide a systematic understanding of these CPCs across temporal, spatial, and spectral domains.
For this study, we carried out a quantitative characterization
of 6,928 CPC ictal waveforms recorded from 50 seizures induced in 11 patients. The duration of these complexes were related to the recovery of responsiveness following seizure termination.
The time to return of responsiveness was recorded. One of two standardized auditory commands were randomized to play at 30-second intervals through a speaker placed near the participant’s head: “Squeeze your left hand twice” or “Squeeze your right hand twice.” Recovery time was defined as the interval between seizure termination and the first instance at which the patient demonstrated compliance to auditory command following seizure termination._x000D_
Results: We compared the total duration of CPCs to the interval from seizure termination to the return of responsiveness (Figure). Across all treatments, recovery time following the ECT-induced seizure was correlated with longer total duration of CPCs (linear mixed-effects models: intercept, 991.92 sec; 95% CI, 669.74 to 1314.1; df = 47; p=1.37×10-7; slope = 4.77 seconds of recovery time/second of CPC duration; 95% CI, 1.56 to 7.97; p = 0.004). Thus, CPC duration is associated with the interval for return of responsiveness in a simple auditory-motor task._x000D_
Conclusions: We demonstrated a significant correlation between the duration of CPCs and the time for the return of responsiveness after ECT. These findings suggest the importance of the electrographic properties of seizures, such as CPCs, in the return of neurological function after ECT. Correlating more specific postictal EEG and cognitive changes with electrographic features of ECT-induced seizures, such as CPCs, may offer further insights into changes in consciousness related to seizures._x000D_
Funding: James S. McDonnell Foundation - McDonnell Center for Systems Neuroscience