In 43 SEEG patients, sleep HFA did not decline with contact-step distance from the clinical SOZ

During NREM sleep, we tested whether 80–300 Hz power (HFA) and slow-wave-phase to HFA coupling (Tort modulation index, MI) increase in non-SOZ bipolar depth pairs nearer to a clinical seizure-onset-zone (SOZ) pair on the same SEEG shaft. Archived per-pair features from 43 patients (728 pairs, 160 SOZ pairs) were examined in two windows from the same run. For 27 eligible patients, the primary Spearman association between step distance and HFA was near zero in both windows (mean rho +0.03; W1 95% CI −0.16 to 0.23, Holm p=0.61; W2 p=0.60). The planned gradient criterion was not met for HFA or MI: MI had a weak negative trend in W1 (rho −0.12, Holm p=0.19) and W2 (rho −0.20, p=0.026, Holm p=0.052), but not in controls for contact position or normal-contact pairs. Exploratory post hoc comparisons separated SOZ from adjacent pairs for HFA, but did not show a significant HFA difference between adjacent and farther pairs. At one contact-step resolution, these results support agreement between the clinical SOZ and HFA borders in this sample. MI remains uncertain. Limitations include clinical SOZ labels, contact-step rather than physical distance, 27 eligible patients, and two windows from the same run rather than an independent cohort.

SEEG · sleep · high-frequency activity · HFA · seizure-onset zone · SOZ · slow-wave coupling · modulation index · contact-step distance · epilepsy