Stereo-electroencephalography Performance in Bilateral Independent/Unclear Scalp Seizures
Bibliographic record
Abstract
Abstract Scalp electroencephalography (EEG) may reveal bilateral independent or unclear (BI/U) ictal onset patterns in patients with focal drug-resistant epilepsy, presenting a challenge to surgical decision-making. The utility of stereo-electroencephalography (SEEG) in this subgroup, particularly the probability of delineating a single seizure onset zone (SOZ) that would permit curative resection, remains poorly understood. This study examined whether BI/U scalp EEG findings could predict SEEG outcomes in this population. We conducted a retrospective cohort study of consecutive patients with focal drug-resistant epilepsy and BI/U ictal onset on scalp EEG who underwent SEEG evaluation at the London Health Sciences Centre (Ontario, Canada) between January 2012 and December 2024. All patients had undergone non-invasive and invasive presurgical assessments. Surgical outcomes were determined using the Engel classification following at least one year of postoperative follow-up. A blinded decision validation sub-study was also performed. Blinded to actual outcomes, the team made decisions regarding SEEG and surgical interventions when patients found to have a single SEEG SOZ were presented. Responses were stratified to inform the added diagnostic value of SEEG. Of 255 SEEG cases screened, 84 patients (33%) met inclusion criteria. The cohort was 56% female, with a median seizure onset age of 12 years (IQR 6–20); 65.5% had temporal lobe epilepsy (TLE). A single SOZ was identified in 14.3% of cases (TLE: 14.5%, extratemporal: 13.8%). Patients with a single SEEG SOZ were found to have shorter recording durations (mean of 11 vs 15.79 days in those with multifocal SEEG SOZs; p=0.009). Curative focal resections were performed in 12% ( n= 10), with long-term Engel I outcomes achieved in one patient (1.2%). Palliative resections occurred in 26% ( n= 22), with Engel I outcomes in 7% ( n= 6). In 50% of the blinded cases, the epilepsy surgery team reported that they would not have recommended SEEG based on phase I data. These findings suggest that patients with BI/U scalp EEG SOZs may be associated with a low likelihood of identifying a single SEEG SOZ and curative outcome. Using BI/U scalp EEG ictal onset as a predictor in preoperative decision-making will assist in refining SEEG candidate selection in this large subgroup.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".