Ictal phase-amplitude coupling supports surgical decision-making in MRI-negative epilepsy with non-localizing SEEG: an illustrative case.

Nishioka, Kazuki; Suzuki, Hiroharu; Mitsuhashi, Takumi; Ueda, Tetsuya; Nomura, Kazuki; Nakajima, Madoka; Sugano, Hidenori; Iimura, Yasushi et al. · Acta Neurochir (Wien) · 2026

case_report · Level V

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Abstract

We report a 14-year-old boy with MRI-negative drug-resistant frontal lobe epilepsy presenting with the chapeau de gendarme sign. SEEG showed diffuse low-voltage fast activity with rapid bilateral propagation, precluding reliable visual localization. Ictal phase-amplitude coupling (PAC) analysis revealed a right-dominant increase in modulation index at seizure onset, localizing to the anterior insula and adjacent prefrontal cortex. Informed by these findings, right frontal disconnection with operculo-insular resection was performed, resulting in seizure freedom at 1 year. This case highlights the utility of ictal PAC analysis in guiding surgical decision-making when SEEG findings are non-localizing.