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Published on: September 20, 2024
Performance of blind source separation in localizing seizure onset from routine scalp-EEG
Jeanne Benoit1,2,3, Samuel Medina Villalon4,5, Stanislas Lagarde4,5
1Institut de Neurosciences Des Systèmes, Aix-Marseille Université, INSERM, INS, 13005, Marseille, France. benoit.j@chu-nice.fr.
Objective:
Blind source separation (BSS), decomposing signals into mixed sources, remains underexplored in ictal source imaging. We evaluated its ability to extract ictal components localizing the seizure onset zone (SOZ) using routine low-density scalp EEG across multiple settings.
Methods:
We analyzed 20 seizures from ten patients with stereo-EEG-defined SOZs, all seizure-free after surgery or RF-thermocoagulation. BSS was computed over 10-, 30-, and 300-s periods preceding clinically and EEG-defined seizure onsets, using FastICA, InfoMax, and SOBI algorithms. Components were visually categorized as ictal or non-ictal. For each computation, the clearest ictal component was labeled best-of-BSS; one per seizure was further labeled unique when enhancing the ictal discharge. We estimated distances between components' localization and the SOZ and assessed sublobar concordance.
Results:
Across 360 BSS computations (8164 components), sublobar SOZ localization occurred in 38.5% of ictal components (mean distance: 44.4 mm), 48.2% of best-of-BSS (36.8 mm), 56.7% of unique (28.9 mm), versus 17.9% of non-ictal components (62.9 mm). InfoMax computed on 300-s periods preceding clinical onset achieved the highest F-scores.
Conclusions:
Under these settings, best-of-BSS components localized the SOZ in 13/20 seizures (8/10 patients), with a median distance of 29.9 mm.
Significance:
InfoMax algorithm incorporating longer time windows improves SOZ localization from routine scalp-EEG.
