Abstracts

Rationale: Kindling is a model of epileptogenesis that posits that repeated seizures increase seizure duration, lower seizure threshold, and increase semiologic manifestations. Seizure spread dynamics are associated with differences in epilepsy surgery outcome. For example, early seizure spread and the presence of focal to bilateral tonic-clonic seizures are associated with poorer outcome after anterior temporal lobectomy (ATL). We hypothesize that longer scalp-EEG seizure duration predicts poorer outcome after ATL.


Methods: We retrospectively reviewed all patients who underwent ATL at University of Alabama at Birmingham Hospital for the treatment of seizures between July 2016 and February 2023. Electrographic seizure duration was recorded for all seizures occurring on scalp EEG during presurgical EMU stay. The EMR was reviewed for demographic information, MRI, PET, ictal SPECT, MEG, neuropsychology testing, pathology, surgical complications, and outcomes. Fishers exact and Steel-Dwass test was used for statistical analysis.


Results: 47 patients underwent ATL over this time-period. A total of 379 seizures were recorded. Of 41 patients with 1-year follow-up, 30 were Engel 1, 7 were Engel 2, 3 were Engel 3, and 1 was Engel 4 outcome. There was no association between median pre-op seizure time and Engel outcome (median seizure time for Engel 1 of 71.8s vs Engel 2-4 of 72.5s; p = 0.4). However, longer median seizure duration was correlated with PET hypometabolism concordant to the resected lobe. Median seizure duration for patients with negative PET was 19.7s (IQR 17.6-58.3; n=8), vs concordant PET of 74.3s (IQR 57.2-93.0; n=32), vs non-concordant PET of 117.5s ( IQR 79.8, 126.7; n=7) (p=0.0010).


Conclusions: While seizure duration was not associated with epilepsy surgery outcome, we found an association between seizure duration and presurgical PET findings. Patients with a negative PET had shorter seizures than patients with a concordant PET, while patients with a non-concordant PET had the longest seizures. This finding suggests that longer seizures are associated with greater regional network dysfunction. Conversely, the association of the longest seizures with PET discordance suggests an even more widespread network-perturbation. Our study was limited by a small sample size, and larger studies are needed to expand on this finding.

Funding: Research reported in this abstract was supported by the National Center for Advancing Translational Sciences of the National Institutes of Health under award number UL1TR003096. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.