Predictive power of phase 1 studies for the identification of seizure onset zone in phase 2 in a pediatric epilepsy cohort.

Objective: Surgical outcomes in the management drug-resistant epilepsy (DRE) rely heavily on proper identification of the seizure onset zone (SOZ). Stereo-electroencephalography (sEEG) can be used to localize SOZs but must be hypothesis driven. Proper utilization of phase 1, noninvasive studies can maximize sEEG planning.

Methods: We performed a retrospective chart review of pediatric patients who underwent sEEG implantation for DRE at a single institution and then subsequently had treatment for an identified SOZ. Each sEEG lead was identified by phase 1, noninvasive data indicating possible SOZ localization. SOZ and patient outcomes were correlated with phase 1 study findings.

Results: One hundred patients with a total of 1777 leads implanted over the span of 10 years were analyzed. A total of 242 SOZs were identified; 41.5% of patients were seizure-free at 1 year, and 75.4% had at least a 50% reduction in seizure frequency. Multivariate modeling showed that anatomical findings such as lesions (odds ratio [OR] = 1.6) and calcifications (OR = 2.5) as well as magnetoencephalography (OR = 1.5) and semiology (OR = 1.7) were the most predictive of SOZ. Predictive power varied with the underlying seizure etiology.

Significance: These results highlight the importance of a multimodal approach to SOZ identification in the noninvasive evaluation phase. A deeper understanding of the potential of each individual preoperative testing modality can guide sEEG placement to minimize surgical risk while maximizing diagnostic yield.