Editors' Note: Comparison of Hemispheric Surgery Techniques for Pediatric Drug-Resistant Epilepsy: An Individual Patient Data Meta-Analysis

In their individual patient data meta-analysis (n = 686 patients), Dr. Chen et al. summarize the safety outcomes and rate of seizure freedom after hemispherotomy for pediatric drug-resistant epilepsy (DRE). In particular, the investigators compared outcomes across different techniques of hemispherotomy. In their propensity score-matched analysis, vertical hemispherotomy was associated with a statistically significantly longer window of seizure freedom as compared with lateral hemispherotomy. However, there were important limitations in this analysis. Notably, the surgical approach was nonrandomized, and there was considerable heterogeneity across clinical sites. The individual patient propensity scores for lateral vs vertical hemispherotomy were also estimated based on adjustment for a small number of covariates, with nearly 20% of data imputed. Furthermore, the 55 included studies were published between 1996 and 2000, half of whom included fewer than 10 patients. This concern is shared by Dr. Ramantani et al. who note that the small number of patients reported by many included studies likely reflects variable levels of surgical experience with DRE. In their more recent multicenter study (5 sites, n = 457 patients), 75% of patients were seizure-free at a mean of 5 years of follow-up (a nearly identical proportion were seizure-free at 5 years in the meta-analysis by Chen et al.). However, in the report by Ramantani et al., there there were no differences in seizure freedom with respect to surgical technique (vertical vs lateral hemispherotomy). Dr. Chen et al. respond that the multicenter analysis by Ramantani et al. suggested a trend toward benefit with vertical hemispherotomy. Moreover, one strength of the analysis by Chen et al. is in the heterogeneity of included cohorts (reflecting diverse practices and clinical experience). The authors maintain their results represent real-world outcomes with respect to surgical approaches. All investigators agree that more high-quality studies are needed before definitive conclusions can be drawn with respect to pediatric epilepsy surgery technique in DRE.