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(29) Enhanced Detection of Interictal Epileptic Discharges Using High-Density sEEG Arrays on LCP Substrate

Thursday, June 12, 2025
5:10 PM - 5:50 PM ET
Location: Sky View
Introduction: Up to 30% of epilepsy cases are drug-resistant and require alternative treatments. For suitable surgical candidates, stereoelectroencephalography (sEEG) is used to localize the epileptogenic zone prior to resection. Recently, sEEG has also shown promise in neuroprosthetics for restoring speech and motor function, as well as in brain network research. However, conventional sEEG devices, typically fabricated with silicone sheets and platinum foil, are limited by low electrode counts and coarse spatial resolution. This restricts their ability to record neural activity at sub-millimeter scales and may contribute to the high failure rates in achieving seizure freedom after surgery.

Methods: In this work, we fabricated high-density sEEG arrays (HD-sEEG) featuring 200 µm micro- and standard-sized ring contacts on a liquid crystal polymer (LCP) thin-film substrate. These hybrid devices maintain the same form factor as clinical sEEG electrodes while offering higher channel counts and smaller feature sizes. Using a novel multi-metal-layer fabrication process, we leveraged LCP’s biocompatibility, low water absorption, and superior long-term reliability compared to other polymeric thin-film materials.

Results: Intraoperative recordings were performed by implanting the HD-sEEG devices in the hippocampus of patients with epilepsy undergoing resective surgery. A neurologist identified interictal discharges, and signals were compared between the ring and HD contacts. In one patient, focal and global interictal discharges were observed throughout the recording. Our analysis revealed that HD contacts: (1) detected more interictal discharges with sub-millimeter precision, (2) captured higher signal power at high frequencies, and (3) enabled directional sensing, allowing for more precise localization of epileptic activity.

Conclusion: These findings highlight HD-sEEG’s potential to enhance seizure onset zone localization and improve surgical outcomes. Furthermore, the increased spatial resolution and signal fidelity of HD-sEEG electrodes could advance neural prosthetics by enabling more precise neural activity sensing.