Same-shaft SEEG N1 responses were not consistent across 8 patients at equal distance (median OR 1.39; 5/8 above 1)

We tested whether stereo-electroencephalography (SEEG) recording contacts on the stimulated electrode shaft show expert-checked early N1 responses more often than contacts on other shafts at equal distance from a stimulated bipolar pair. We analyzed an archived stimulated-pair-by-contact table from OpenNeuro ds005448 (STReEF), covering 8 patients (STREEF06-13) and clinical 1-2 mA single pulses. The primary analysis included gray-matter contacts 10-50 mm from the pair midpoint (10,244 rows; 808 same-shaft rows), stratified by stimulated pair and 5-mm distance bin. The median patient-specific Mantel-Haenszel odds ratio was 1.39 (5 of 8 above 1); the exact sign-flip test gave p = 0.070 one-sided (0.14 two-sided), and the pooled odds ratio was 1.17. Two patients had strong same-shaft excesses (OR 3.21 and 5.94; within-patient permutation p = 0.001 and 0.0005), while three had OR below 1. Sensitivity analyses gave median OR 1.11 for gray plus other tissue (6/8 above 1, p = 0.16) and 1.21 for all tissue (6/8 above 1, p = 0.090). These data show no consistent same-shaft excess across patients at equal distance. They do not exclude a moderate average effect: there were 8 patients and few same-shaft contacts beyond 30 mm. Shaft membership is confounded with anatomy, so any observed effect does not prove conduction along an electrode track. The evidence comes from one center, clinical currents, binary expert labels, and Euclidean distance.

stereo-electroencephalography · SEEG · cortico-cortical evoked potentials · CCEP · N1 response · electrode shaft · distance · Mantel-Haenszel odds ratio · permutation test · OpenNeuro · STReEF