Slow modulations of high-frequency activity (40-140-Hz) discriminate preictal changes in human focal epilepsy

• Main Author: Alvarado-Rojas, C
• Publication Date: 2014
• Other Authors: Valderrama, M, Fouad-Ahmed, A, Feldwisch-Drentrup, H, Ihle, M, Teixeira, C. A., Sales, F., Schulze-Bonhage, A, Adam, C, Dourado, A., Charpier, S, Navarro, V, Le Van Quyen, M
• Format: Article
• Language: por
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: https://hdl.handle.net/10316/109681; https://doi.org/10.1038/srep04545
• topic: Adolescent; Adult; Brain Waves; Child; Child, Preschool; Epilepsies, Partial; Female; Humans; Male; Middle Aged; Young Adult; Electroencephalography

Recent evidence suggests that some seizures are preceded by preictal changes that start from minutes to hours before an ictal event. Nevertheless an adequate statistical evaluation in a large database of continuous multiday recordings is still missing. Here, we investigated the existence of preictal changes in long-term intracranial recordings from 53 patients with intractable partial epilepsy (in total 531 days and 558 clinical seizures). We describe a measure of brain excitability based on the slow modulation of high-frequency gamma activities (40-140 Hz) in ensembles of intracranial contacts. In prospective tests, we found that this index identified preictal changes at levels above chance in 13.2% of the patients (7/53), suggesting that results may be significant for the whole group (p < 0.05). These results provide a demonstration that preictal states can be detected prospectively from EEG data. They advance understanding of the network dynamics leading to seizure and may help develop novel seizure prediction algorithms.