Progressive Slowing of the Clonic Phase Predicts Prolonged Postictal Immobility in Tonic-clonic Seizures
Abstract number :
2.106
Submission category :
3. Neurophysiology / 3A. Video EEG Epilepsy-Monitoring
Year :
2024
Submission ID :
1093
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: John Phamnguyen, BMSc MBBS FRACP – Royal Brisbane and Women's Hospital
Fred Tremayne, BS – Royal Brisbane and Women's Hospital
Lata Vadlamudi, MBBS, FRACGP, FRACP, PhD, GradCertDiagnosticGenomics – Royal Brisbane and Women's Hospital
Cecilie Lander, MBBS, FRACP – Royal Brisbane and Women's Hospital
Stephen Walsh, BAppSc, MBBS, FRACP – Royal Brisbane and Women's Hospital
Xiaohua Chen, MBBS, PhD, FRACP – Royal Brisbane and Women's Hospital
Alice-Ann Sullivan, MBBS, BA, FRACP – Royal Brisbane and Women's Hospital
Viktor Vegh, BAppSci PhD MComm GradCert – University of Queensland
David Reutens, MBBS, MD, FRACP, FAHMS – Royal Brisbane and Women's Hospital
Rationale: Postictal immobility, defined as the absence of motion and impaired arousal following a tonic-clonic seizure, has emerged as a clinical biomarker of interest in evaluating tonic-clonic seizure severity and sudden unexpected death in epilepsy (SUDEP) risk (Kuo et al., 2016, Asadollahi et al., 2018). Prolonged post-ictal immobility is associated with severe respiratory dysfunction resulting in hypoxaemia and hypercapnia (Kuo et al., 2016, Seyal et al., 2013). Little is known about the factors contributing to prolongation of post-ictal immobility. In this study, we evaluated the electroclinical factors associated with post-ictal immobility.
Methods: We analysed 110 tonic-clonic seizures in 52 patients recruited at the Royal Brisbane and Women’s Hospital (RBWH), Brisbane, Australia. Video-EEG recordings from 2016 to 2022 capturing tonic-clonic seizures were evaluated, and demographic and clinical data were collected from electronic medical records. Electroclinical features, comprising the duration, semiology and EEG pattern of different phases of a tonic-clonic seizure, were evaluated. We calculated the ratio between the durations of tonic and clonic phases of the seizure and recorded the presence of progressive slowing of the clonic phase, defined as the occurrence of at least two consecutive increases in the duration of the silent period between successive clonic jerks (Vlachou et al., 2022).
Results: Progressive slowing of the clonic phase was associated with a significantly longer duration of postictal immobility (p < 0.001) but no association was seen between progressive slowing of the clonic phase and the duration of post-ictal EEG suppression (p = 0.537). Compared to those without progressive slowing of the clonic phase, seizures with this feature had a longer duration of the tonic phase (p < 0.001) and a higher ratio between the durations of tonic and clonic phases (p < 0.001).
Conclusions: Progressive slowing of the clonic phase is thought to be secondary to gradually increasing silent (inhibitory) periods. Its association with longer periods of postictal immobility suggests that the pathophysiological mechanisms underlying inhibition of clonic jerks and impaired postictal arousal may be shared. Postictal immobility may be relevant to SUDEP risk because the prevention of head repositioning from the prone position may contribute to further postictal apnoea.
Funding: No funding or support was provided for this study.
Neurophysiology