A semiology-driven framework for explorations of temporal lobe epilepsy

Temporal lobectomy is effective for drug-resistant temporal lobe epilepsy (TLE), but broad resections risk neuropsychological morbidity. Stereo-electroencephalography (SEEG) supports hypothesis-driven exploration of seizure networks, where semiology-together with imaging, scalp EEG, and neuropsychology-anchors implantation strategies without serving as a sole classifier. We aimed to define common SEEG implantation patterns in TLE from a stereotaxic functional-anatomic perspective and test their reproducibility.

We analyzed 72 patients (60 main, 12 validation) with drug-resistant TLE who underwent SEEG. Implantation strategies converged into four reproducible patterns -mesial-lateral temporal, temporal-basal-occipital, anterior perisylvian, and perisylvian-guided primarily by non-invasive data with semiology exerting the greatest influence. Seizure semiology, neuroimaging, and electrophysiological recordings were systematically collected. To evaluate the reproducibility of implantation patterns, machine learning classifiers (Naïve Bayes, random forests) were trained to predict implantation classification based on semiological features and electrode coverage. Surgical and neuropsychological outcomes were assessed prospectively at 1 year.

Classification based on semiology alone achieved moderate accuracy in predicting outcomes (precision 66%, recall 65%). Electrode coverage provided substantially higher predictive power (precision 87%, recall 85%). Crucially, semiological features showed strong concordance with the actual electrode implantation patterns (precision 84%, recall 82%), demonstrating that semiology functions as a reproducible heuristic for guiding implantation strategy. Following SEEG, 94% of patients proceeded to definitive therapy (82% tailored resection, 12% neuromodulation), with a 1-year seizure-freedom rate of 73%, independent of lesion status or implantation category. Postoperatively, 26% of resection patients demonstrated verbal memory decline, more frequently after left-sided (38%) than right-sided (7.7%) interventions.

This study characterizes reproducible SEEG implantation patterns in TLE, viewed from a stereotactic functional-anatomic perspective and informed by semiology. Computational analyses were used to examine the consistency of these patterns, offering insights into how implantation strategies relate to network localization and potential surgical approaches.