Abstract
Background
Temporal lobe epilepsy associated with hippocampal sclerosis (TLE-HS) is a surgically treatable epileptic syndrome. While the core of pre-surgical evaluations rely on video-EEG, recent studies question the necessity of recorded seizures denying a possible role of ictal EEG in surgical decision. This study aims to retrospectively assess the prognostic value of EEG ictal patterns in TLE-HS, in order to identify which patients need further investigations before offering surgery.
Methods
We included TLE-HS patients who underwent surgery with at least one captured seizure during non-invasive pre-surgical video-EEG recordings. They were classified in “mesial” and “lateral/mixed”, according to the ictal EEG patterns, defined by the frequency of the discharge (mesial ≥ 5 Hz, lateral < 5 Hz). Seizure outcome was assessed by Engel’s Class. Statistical analyses were performed to evaluate associations between EEG patterns and post-surgical outcomes.
Results
Sixty-nine exhibited a mesial pattern, forty- two displayed lateral/mixed patterns. Mesial pattern group had a significantly higher rate of postsurgical seizure freedom (82.7% vs. 28.6%). Gender, age of onset, age at surgery, duration of epilepsy, seizure frequency, and lateralization did not influence the outcome. Mesial pattern significantly correlated with favorable outcomes (p < 0.001), suggesting its potential predictive value.
Conclusion
This retrospective study proposes ictal EEG patterns as possible predictors of postoperative prognosis in TLE-HS. A mesial pattern correlates with better outcomes, indicating a potentially more circumscribed epileptogenic zone. Patients with lateral/mixed patterns may benefit from additional investigations to delineate the epileptogenic zone. Further studies are warranted to validate and extend these findings.
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Data availability
All data are available on request.
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Acknowledgements
We would like to take di opportunity to thank the EEG technologists drs Maria Teesco, Grazia Iovino, Giulia Vona and Alessandro Romano for performing meticulous Video-EEG recordings in all patients
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The study was part of a large project concerning observational retrospective researches on seizure outcome after epilepsy surgery performed for clinical purpose, approved by the Local Ethical Committee. All study participants gave their written consent to the use of their clinical and instrumental data, in an aggregate and anonymous manner. The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
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Di Gennaro, G., Romigi, A., Quarato, P.P. et al. Prognostic value of scalp EEG ictal patterns in epilepsy surgery of hippocampal sclerosis. Neurol Sci (2024). https://doi.org/10.1007/s10072-024-07564-y
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DOI: https://doi.org/10.1007/s10072-024-07564-y