Pediatric peri-insular hemispherotomy and functional hemispherectomy for severe medically refractory epilepsy: comparison of two techniques

Purpose: Since it was first described in the 1970s, functional hemispherotomy has been an essential tool in treating disabling, medically refractory epilepsy resulting from diffuse unilateral hemispheric disease. We report our experience with 23 patients who underwent hemispherotomy, both using the functional hemispherotomy (FH) as well as a modified peri-insular hemispherotomy (PIH) technique. We present the surgical technique for the latter, review outcomes following disconnection surgery and discuss the differences between the techniques when it comes to complications and postoperative results. Methods: A retrospective study of 23 patients with refractory seizures who underwent cerebral hemispherectomy. A thorough analysis of the clinical, imaging, surgical features and postoperative results was performed. We also present the surgical technique for a modified PIH technique. Results: Between 2000 and 2020, 23 pediatric patients with refractory seizures underwent hemispherotomy (12 FHs, 11 modified PIHs). 91.3% of patients were seizure free at 6 months, 87% at 1 year, and 78.3% at last follow-up. None of the 23 patients presented Engel IV outcome. FH was found to have statistically longer surgical duration (5 +/- 1.5 vs. 3.83 +/- 0.5 h; p = <0.001). Neurocognition was improved in two thirds of the patients (66.9%). Our study also shows improvement of motor activity in the majority of the patients, regardless of the pathology and surgical technique. In the present report we modified the Cook et al. technique by implementing an amygdalohippocampectomy with resection of the tail of the hippocampus posteriorly and medially, to achieve temporo-occipital disconnection, instead of a complete temporal lobectomy. Conclusion: When patients are wisely selected, the hemispherectomy procedure should be considered as a most attractive and curative treatment for children with refractory seizures, not only giving the patient a high chance of seizure freedom but also providing an improvement in motor and cognitive skills. In our particular case and based on the present study, the modified PIH proves to be a highly effective technique. It not only has a shorter surgical time but also a very low complication rate.