Authors :
Presenting Author: Matthew Moye, BSc – Duke University
Birgit Frauscher, M.D. Ph.D. – Duke University
John Thomas, PhD – Duke University
Petr Klimeš, Ph.D. – Duke University
Derek Southwell, MD PhD – Duke University
Lara Wadi, M.D. – Duke University School of Medicine
Praveen Ramani, M.D. – Duke University School of Medicine
Tamir Avigdor, PhD – Duke University
Kassem Jaber, M.Sc. – Duke University
Prachi Parikh, MD – Duke University
Rationale:
Interictal epileptiform discharges (IEDs) or spikes are valuable interictal stereo-electroencephalography (SEEG) biomarkers utilized to localize the epileptogenic zone during epilepsy surgery. Despite evidence that spike morphology varies across vigilance states, how interictal epileptiform discharge (IED) morphology before and after a seizure (preictal and postictal periods) is yet to be systematically investigated. A deeper understanding of these morphological variations is necessary for our understanding of seizure initiation, termination, and thereby a potential improvement in clinical careMethods:
We analyzed patients with drug-resistant epilepsy who underwent long-term SEEG monitoring for phase II presurgical evaluation. Board-certified epileptologists visually annotated seizure onsets, offsets, and seizure onset zones for electro-clinical seizures that occurred during wakefulness. SEEG recordings were processed using a bipolar montage of adjacent contacts on an SEEG electrode. IEDs were detected by a previously validated detector [1]. IED features (rate, amplitude, duration) were analyzed across 10-minute SEEG segments (baseline, preictal, postictal) across seizure types (focal impaired consciousness, focal preserved consciousness, and focal to bilateral tonic-clonic). We utilized the Wilcoxon sign-ranked test for p-value and Cliff’s delta for effect size calculation.
Results:
In 26 patients, we analyzed 26 FIC, 3 FPC and 12 FBTC. Significant changes in IED amplitude were observed primarily in patients with FIC and FBTC seizures. Post-ictal IED amplitude significantly decreased compared to baseline in FIC seizures (p < 0.01, d = 0.48, n=26). Post-ictal IED amplitudes significantly decreased compared to preictal IED amplitudes in in FBTC seizures (p < 0.01, d = 1, n=12) as well as post-ictal IED amplitudes (p < 0.01, d = 0.93, n=12). Post-ictal IED durations significantly increased compared to baseline in FIC seizures (0 < 0.01, d = 0.32). IED rates did not significantly differ regardless of seizure type (p > 0.05). The IED rates in FIC seizures were (baseline: 12.10 ± 8.91; pre: 9.99 ± 7.21; post: 12.43 ± 6.60 spikes/channel/min), and in FBTC seizures were (baseline: 12.40 ± 11.24; pre: 12.84 ± 10.94; post: 15.06 ± 7.03 spikes/channel/min), while FPC seizures did not exhibit significant changes in IED amplitude, duration, or rate, this can be explained by a small sample size n = 3.Conclusions:
Our results show that amplitude significantly changes for segments pre and post ictally. This result is most significant in FIC and FBTC seizures. Duration significantly changed only for FIC. These morphological changes in IED amplitude could provide valuable insights, that help us better understand the mechanisms of seizure initiation and termination. These outcomes can have implications for more customized neuromodulation strategies and surgical planning, leading to improved patient care for those with drug-resistant epilepsy.Funding:
None