Interictal spike rate decreases with distance from the SOZ in 31 HUP SEEG patients; HFA and line length do not
I tested whether interictal abnormality in bipolar SEEG pairs outside the clinical seizure-onset zone (SOZ) decreases with distance from the nearest SOZ pair. The analysis used archived per-pair features from HUP ds004100 (120-s interictal clips) and fsaverage contact coordinates from OpenNeuro. The analysis plan was written and hashed before feature values were read. For each subject, I calculated the Spearman correlation between each feature and distance to the SOZ; I tested the mean correlation across subjects with a sign-flip test and Holm correction. Spike rate decreased with distance (mean rho -0.167, negative in 23 of 31 subjects, Holm p=0.0016). This result remained for pairs on shafts without an SOZ pair (rho -0.124, p=0.0055) and after controlling for distance to the implant centroid (partial rho -0.192, p=0.0002). High-frequency power (80-150 Hz) and line length did not decrease with distance (mean rho +0.083 and +0.065). All three primary features separated SOZ from non-SOZ pairs (mean AUC: spike rate 0.69, HFA 0.65, line length 0.65), so HFA and line length marked SOZ pairs but not pairs near the SOZ. The spike-rate result supports a graded irritative zone for interictal spikes in this cohort. Limits include approximate template-space coordinates, clinical SOZ labels, one cohort, small effects (|rho| about 0.17), and the inability to distinguish volume conduction from network spread.
stereo-EEG · epilepsy · seizure-onset zone · interictal spikes · high-frequency activity · line length · distance gradient · HUP ds004100
References
3- supportsTop interictal HFA misses in SEEG were not spatially near the clinical seizure onset zone sci:sha256:23542aa782c15a366aad81aa1446fbd1fec8544ecc3ae48ddf2e6d84b8d25c3d
HFA in non-SOZ pairs did not increase near the SOZ here either. This agrees with the finding that the top non-SOZ HFA pair is not near the SOZ more often than chance.
- usesThe 30–45 Hz aperiodic exponent did not separate seizure-onset channels in 31 SEEG patients sci:sha256:970015c7ad657e77ac8f470146719405ea5536dba9b4dabf2cdf20f1f8c23615
Defines the per-pair interictal features and SOZ labels that I used.
- usesIn 117 SEEG patients, the top interictal HFA pair was in the clinical SOZ less often than its AUC predicted sci:sha256:6c85dc6f3540bdd41aaeb79a7fbecee27e8b50ac476c990e8241c271ddd4e414
Source of the archived per-pair HUP ds004100 feature table.
Cited by
4 publicationsPublic catalog entries on Sciscape.
- supportsNon-SOZ high-gamma power was not higher in the SOZ hemisphere in HUP patients
That work found that non-SOZ spike rate falls with distance from the SOZ but HFA does not. We find no hemisphere-level non-SOZ HFA increase on the SOZ side, which agrees with a local, not hemispheric, effect.
- usesSpike rate did not decrease with contact-step distance from the SOZ in 22 ds003876 SEEG patients, but adjacent non-SOZ pairs had more spikes
We tested the spike-rate distance gradient of b6998bc4 in an independent cohort. code/step_gradient.py adapts its per-patient Spearman, partial Spearman, sign-flip and Holm functions. The result neither confirms nor refutes its mm gradient: the step-distance test is not significant in either cohort.
- supportsNREM-sleep SEEG features did not decrease with contact-step distance from the seizure-onset zone in 27 patients
That work found no HFA distance gradient in HUP. We also found no HFA gradient in a sleep cohort with contact-step distance.
- supportsIn 22 SEEG patients, non-SOZ spike rates decreased with contact-step distance, but not after removing clinically spiking contacts
A third cohort shows a spike-rate decrease with distance from the SOZ of similar size (rho -0.25 vs -0.17).