Comparison of the real-world effectiveness of vertical versus lateral functional hemispherotomy techniques for pediatric drug-resistant epilepsy: A post hoc analysis of the HOPS study

Aria Fallah, Evan Lewis, George M. Ibrahim, Olivia Kola, Chi Hong Tseng, William B. Harris, Jia Shu Chen, Kao Min Lin, Li Xin Cai, Qing Zhu Liu, Jiu Luan Lin, Wen Jing Zhou, Gary W. Mathern, Matthew D. Smyth, Brent R. O'Neill, Roy W.R. Dudley, John Ragheb, Sanjiv Bhatia, Daniel Delev, Georgia RamantaniJosef Zentner, Anthony C. Wang, Christian Dorfer, Martha Feucht, Thomas Czech, Robert J. Bollo, Galymzhan Issabekov, Hongwei Zhu, Mary Connolly, Paul Steinbok, Jian Guo Zhang, Kai Zhang, Eveline Teresa Hidalgo, Howard L. Weiner, Lily Wong-Kisiel, Samuel Lapalme-Remis, Manjari Tripathi, Poodipedi Sarat Chandra, Walter Hader, Feng Peng Wang, Yi Yao, Pierre Olivier Champagne, Tristan Brunette-Clément, Qiang Guo, Shao Chun Li, Marcelo Budke, Maria Angeles Pérez-Jiménez, Christian Raftopoulos, Patrice Finet, Pauline Michel, Karl Schaller, Martin N. Stienen, Valentina Baro, Christian Cantillano Malone, Juan Pociecha, Noelia Chamorro, Valeria L. Muro, Marec von Lehe, Silvia Vieker, Chima Oluigbo, William D. Gaillard, Mashael Al-Khateeb, Faisal Al Otaibi, Niklaus Krayenbühl, Jeffrey Bolton, Phillip L. Pearl, Alexander G. Weil

Research output: Contribution to journalArticlepeer-review


Objective: This study was undertaken to determine whether the vertical parasagittal approach or the lateral peri-insular/peri-Sylvian approach to hemispheric surgery is the superior technique in achieving long-term seizure freedom. Methods: We conducted a post hoc subgroup analysis of the HOPS (Hemispheric Surgery Outcome Prediction Scale) study, an international, multicenter, retrospective cohort study that identified predictors of seizure freedom through logistic regression modeling. Only patients undergoing vertical parasagittal, lateral peri-insular/peri-Sylvian, or lateral trans-Sylvian hemispherotomy were included in this post hoc analysis. Differences in seizure freedom rates were assessed using a time-to-event method and calculated using the Kaplan–Meier survival method. Results: Data for 672 participants across 23 centers were collected on the specific hemispherotomy approach. Of these, 72 (10.7%) underwent vertical parasagittal hemispherotomy and 600 (89.3%) underwent lateral peri-insular/peri-Sylvian or trans-Sylvian hemispherotomy. Seizure freedom was obtained in 62.4% (95% confidence interval [CI] = 53.5%–70.2%) of the entire cohort at 10-year follow-up. Seizure freedom was 88.8% (95% CI = 78.9%–94.3%) at 1-year follow-up and persisted at 85.5% (95% CI = 74.7%–92.0%) across 5- and 10-year follow-up in the vertical subgroup. In contrast, seizure freedom decreased from 89.2% (95% CI = 86.3%–91.5%) at 1-year to 72.1% (95% CI = 66.9%–76.7%) at 5-year to 57.2% (95% CI = 46.6%–66.4%) at 10-year follow-up for the lateral subgroup. Log-rank test found that vertical hemispherotomy was associated with durable seizure-free progression compared to the lateral approach (p =.01). Patients undergoing the lateral hemispherotomy technique had a shorter time-to-seizure recurrence (hazard ratio = 2.56, 95% CI = 1.08–6.04, p =.03) and increased seizure recurrence odds (odds ratio = 3.67, 95% CI = 1.05–12.86, p =.04) compared to those undergoing the vertical hemispherotomy technique. Significance: This pilot study demonstrated more durable seizure freedom of the vertical technique compared to lateral hemispherotomy techniques. Further studies, such as prospective expertise-based observational studies or a randomized clinical trial, are required to determine whether a vertical approach to hemispheric surgery provides superior long-term seizure outcomes.

Original languageEnglish (US)
Pages (from-to)2707-2718
Number of pages12
Issue number11
StatePublished - Nov 2021


  • hemispherectomy
  • hemispherotomy
  • seizure outcomes
  • technique

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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