TY - JOUR

T1 - Progressive slowing of clonic phase predicts postictal generalized EEG suppression

AU - Vlachou, Maria

AU - Ryvlin, Philippe

AU - Arbune, Anca Adriana

AU - Armand Larsen, Sidsel

AU - Skræp Sidaros, Annette

AU - Cacic Hribljan, Melita

AU - Fabricius, Martin

AU - Beniczky, Sándor

N1 - Funding Information: We would like to thank Bo Martin Bibby from Aarhus University, Department of Statistics, for the help with the statistical analysis. This project was developed in collaboration with the European Reference Network for Rare and Complex Epilepsies EpiCARE ( https://epi‐care.eu ), and it has been partially supported by the SEVERITY Swiss NSF/Div3 project (grant #320030–179 240) and The PEDESITE Swiss NSF Sinergia project (grant no. SCRSII5 193 813/1). Publisher Copyright: © 2022 The Authors. Epilepsia published by Wiley Periodicals LLC on behalf of International League Against Epilepsy.

PY - 2022

Y1 - 2022

N2 - Objective: Postictal generalized electroencephalography (EEG) suppression (PGES) is a surrogate marker of sudden unexpected death in epilepsy (SUDEP). It is still unclear which ictal phenomena lead to prolonged PGES and increased risk of SUDEP. Semiology features of generalized convulsive seizure (GCS type 1) have been reported as a predictor of prolonged PGES. Progressive slowing of clonic phase (PSCP) has been observed in GCSs, with gradually increasing inhibitory periods interrupting the tonic contractions. We hypothesized that PSCP is associated with prolonged PGES. Methods: We analyzed 90 bilateral convulsive seizures in 50 consecutive patients (21 female; age: 11–62 years, median: 31 years) recruited to video-EEG monitoring. Five raters, blinded to all other data, independently assessed the presence of PSCP. PGES and seizure semiology were evaluated independently. We determined inter-rater agreement (IRA) for the presence of PSCP, and we evaluated its association, as well as that of other ictal features, with the occurrence of PGES, prolonged PGES (≥20 s) and very prolonged PGES (≥50 s) using multivariate logistic regression analysis. Results: We found substantial IRA for the presence of PSCP (percent agreement: 80%; beyond-chance agreement coefficient:.655). PSCP was an independent predictor of the occurrence of PGES and prolonged PGES (p <.001). All seizures with very prolonged PGES had PSCP. GCS type 1 was an independent predictor of occurrence of PGES (p =.02) and prolonged PGES (p =.03) but not of very prolonged PGES. Only half of the seizures with very prolonged PGES were GCS type 1. Significance: PSCP predicts prolonged PGES, emphasizing the importance of gradually increasing inhibitory phenomena at the end of the seizures. Our findings shed more light on the ictal phenomena leading to increased risk of SUDEP. These phenomena may provide basis for algorithms implemented into wearable devices for identifying GCS with increased risk of SUDEP.

AB - Objective: Postictal generalized electroencephalography (EEG) suppression (PGES) is a surrogate marker of sudden unexpected death in epilepsy (SUDEP). It is still unclear which ictal phenomena lead to prolonged PGES and increased risk of SUDEP. Semiology features of generalized convulsive seizure (GCS type 1) have been reported as a predictor of prolonged PGES. Progressive slowing of clonic phase (PSCP) has been observed in GCSs, with gradually increasing inhibitory periods interrupting the tonic contractions. We hypothesized that PSCP is associated with prolonged PGES. Methods: We analyzed 90 bilateral convulsive seizures in 50 consecutive patients (21 female; age: 11–62 years, median: 31 years) recruited to video-EEG monitoring. Five raters, blinded to all other data, independently assessed the presence of PSCP. PGES and seizure semiology were evaluated independently. We determined inter-rater agreement (IRA) for the presence of PSCP, and we evaluated its association, as well as that of other ictal features, with the occurrence of PGES, prolonged PGES (≥20 s) and very prolonged PGES (≥50 s) using multivariate logistic regression analysis. Results: We found substantial IRA for the presence of PSCP (percent agreement: 80%; beyond-chance agreement coefficient:.655). PSCP was an independent predictor of the occurrence of PGES and prolonged PGES (p <.001). All seizures with very prolonged PGES had PSCP. GCS type 1 was an independent predictor of occurrence of PGES (p =.02) and prolonged PGES (p =.03) but not of very prolonged PGES. Only half of the seizures with very prolonged PGES were GCS type 1. Significance: PSCP predicts prolonged PGES, emphasizing the importance of gradually increasing inhibitory phenomena at the end of the seizures. Our findings shed more light on the ictal phenomena leading to increased risk of SUDEP. These phenomena may provide basis for algorithms implemented into wearable devices for identifying GCS with increased risk of SUDEP.

U2 - 10.1111/epi.17434

DO - 10.1111/epi.17434

M3 - Journal article

C2 - 36208032

AN - SCOPUS:85141374276

VL - 63

SP - 3204

EP - 3211

JO - Epilepsia

JF - Epilepsia

SN - 0013-9580

IS - 12

ER -