Across 120 SEEG patients, shaft-end position changed end-stratified SOZ HFA AUC by +0.002

We tested whether shaft-end position accounts for part of the interictal high-frequency activity (HFA, 80–150 Hz) signal at seizure-onset-zone (SOZ) bipolar stereoelectroencephalography (SEEG) pairs. We used unchanged archived per-pair tables from five OpenNeuro datasets (ds004100, ds003876, ds007118, ds007119, ds007120, and ds005398) covering 120 patients: HUP 30, ds003876 29, NREM sleep 43, and UCLA 18. An end pair contained the lowest or highest contact number of its shaft; contact 1 was assumed to be the deep tip, but this was not verified from coordinates. Patient was the unit; tests used 20,000 sign-flip draws, bootstrap 95% confidence intervals, and Holm correction across four primary tests. Non-SOZ end pairs did not have higher HFA than interior pairs (mean AUC 0.511, 95% CI 0.478–0.545, Holm p = 1). A descriptive low-number-end excess appeared in the two awake cohorts (pooled AUC 0.557, p = 0.009); the high-number end did not (AUC 0.470, p = 0.15), and sleep cohorts had no low-end excess. HFA separated SOZ pairs within interior pairs (mean AUC 0.684, 95% CI 0.643–0.724, 94 of 114 patients above 0.5, 19 below, Holm p = 0.0002). The all-pair SOZ AUC minus the end-stratified AUC was +0.002 (95% CI −0.010 to +0.015, Holm p = 1), below the prespecified materiality rule of >0.02. Line length and spike rate gave differences of +0.003 and +0.002 (both p > 0.45). A label-free end correction changed top-1 HFA SOZ hits from 38 to 36 of 120 (3 better, 5 worse; p = 0.73). SOZ fractions were 12.0% for end pairs and 11.4% for interior pairs. The top-1 HFA pair was an end pair in 42.5% of patients; end pairs were 24.3% of pairs (descriptive, not tested). Limits include short interictal clips (20–180 s), clinical SOZ labels, end status inferred from contact numbers rather than coordinates or tissue labels, possible reclassification from removed bad contacts, and four different HFA definitions.

stereoelectroencephalography · SEEG · epilepsy · seizure onset zone · SOZ · high-frequency activity · HFA · interictal · shaft-end position · electrophysiology