Safety, feasibility, and technique of stereo-electroencephalography in children younger than 3 years

OBJECTIVE: Stereo-electroencephalography (sEEG) is a minimally invasive technique for intracranial monitoring that was traditionally reserved for adults but is increasingly used in very young pediatric patients with drug-resistant epilepsy. The aim of this study was to evaluate its safety, feasibility, and technical considerations in pediatric patients younger than 3 years. METHODS: The authors reviewed the records of 21 children younger than 3 years who underwent sEEG monitoring at Lucile Packard Children's Hospital between February 2013 and March 2025. Data were collected from patients' clinical records and operative reports. Skull thickness was measured at the thinnest point under electrodes. Primary outcome variables were 1) sEEG-related complications, and 2) electrode placement entry point error (EPE) and target point error (TPE). RESULTS: Twenty-one patients (67% male) had a mean ± SE age at seizure onset of 0.5 ± 0.5 years (range birth-1.6 years). Patients underwent 23 sEEG surgeries at a mean age of 2.2 ± 0.1 years (range 0.9-2.7 years). The Mayfield headframe with the Infinity Support System was used in 65% of cases. Overall, a mean of 19 ± 1 (range 9-27) depth electrodes were placed per patient. In total, 443 electrodes were placed, most often in the frontal (189 electrodes, 43%) and temporal (121 electrodes, 27%) regions. A total of 440 bolts were used, and the most common sizes were 20 mm (68%) and 13 mm (18%); 3 electrodes were placed without bolts. The mean skull thickness at the thinnest point of electrode placement was 2.0 ± 0.1 mm (range 1.5-3.2 mm). For 417 electrodes available for analysis, the mean EPE was 1.9 ± 0.1 mm, and the mean TPE was 2.8 ± 0.1 mm. Aside from a CSF leak from a bolt in 1 patient, there were no complications. The most common procedures included open resection (61% of sEEG cases) and laser ablation (30%). Procedures were performed at a mean of 43 ± 11 days (range 0-150 days) after sEEG removal, with a mean patient age of 2.3 ± 0.1 years (range 1.2-2.9 years). CONCLUSIONS: This study supports the safety and feasibility of sEEG in children younger than 3 years, even in those with a skull thickness < 2 mm. Moreover, the authors report the youngest patient in the literature to have undergone sEEG at 11 months, without complications. The minimum skull thickness in which an electrode was successfully secured with a bolt was 1.5 mm. With appropriate technical adaptations, sEEG can be accurately performed in children younger than 3 years.