Determinants of epileptogenic zone identification and seizure outcome in children with refractory epilepsy undergoing stereoelectroencephalography

Abstract

OBJECTIVE The objective of this paper was to investigate the factors associated with successful epileptogenic zone (EZ) identification and postsurgical seizure freedom in pediatric patients with drug-resistant epilepsy who underwent first-time stereoelectroencephalography (SEEG). METHODS The authors conducted a retrospective cohort study of all consecutive patients younger than 18 years of age at the time of recommendation for invasive evaluation with SEEG who were treated from July 2009 to June 2020. The authors excluded patients who had undergone failed prior resective epilepsy surgery or prior intracranial electrode evaluation for seizure localization. For their primary outcome, the authors evaluated the relationship between clinical and radiographic factors and successful identification of a putative EZ. For their secondary outcome, the authors investigated whether these factors had a significant relationship with seizure freedom (according to the Engel classification) at last follow-up. RESULTS The authors included 101 patients in this study. SEEG was safe, with no major morbidity or mortality experienced. The population was complex, with an MRI lesion present in less than 40% of patients and patients as young as 2.9 years included. A proposed EZ was identified in 88 (87%) patients. Patients with an older onset of epilepsy (OR 1.20/year, p = 0.04) or epilepsy etiology suspected to be due to a developmental lesion (OR 8.38, p = 0.02) were more likely to have proposed EZ identification. Patients with a preimplantation bilateral seizure-onset hypothesis (OR 0.29, p = 0.047) and those who underwent longer periods of monitoring (OR 0.86/day, p = 0.006) were somewhat less likely to have proposed EZ identification. The presence of an MRI lesion was a positive factor on secondary analyses (OR 4.18, p = 0.049; 1-tailed test). Fifty percent of patients who underwent surgical treatment with resection or laser ablation achieved Engel class I outcomes, in contrast to 0% of patients who underwent neuromodulation. Patients with a preimplantation hypothesis in the frontal/parietal lobes had increased odds of seizure freedom compared with patients with a hypothesis in other locations (OR 3.64, p = 0.01). CONCLUSIONS Pediatric SEEG is safe and often identifies a proposed resectable EZ. These results suggest that SEEG is effective in patients with frontal/parietal preimplantation hypothesis, with or without identified lesions on MRI.