Abstracts

Rationale: The number one cause of surgical failure after hemispherectomy is incomplete disconnection. Common areas of interest are corpus callosum, frontal basal cortex, and insular cortex. Among these, the insular resection is not routinely performed because of the risk of injury to main arteries on the surface of the insula and to the deep structures. This study was aimed to evaluate the usefulness of intraoperative electrocorticography (ECoG) on insular cortex for improving the outcome of modified functional hemispherectomy. Methods: After modified functional hemispherectomy, further resection of insular cortex was determined by presence of epileptiform activities on ECoG over insular cortex. All subjects underwent intraoperative ECoG monitoring on ipsilateral insular cortex during modified functional hemispherectomy at Florida Hospital for Children from January 2012 to May 2014. Details about demographic data, clinical finding and surgical outcome were reviewed retrospectively. This study was approved by the institutional IRB. Results: A total of 11 patients (age, 0.5-12.0 years; 5 boys and 6 girls) were included in the study. Etiology included 5 perinatal strokes and 6 focal cortical dysplasia (FCD). Ten of 11 patients (90.9%) became seizure free (ILAE I) with a mean follow-up duration of 12.4 months (SD ± 6.4 months). Epileptiform discharges on insular cortex were identified in 3 of 11 patients (27.2%). All three of them had FCD as the pathology while only one showed insular involvement on pre-operative MRI. Conclusions: Intraoperative insular ECoG monitoring could be performed safely without adding risk to the patients while providing tailored approach to insular resection. Patients with possible FCD may benefit from this approach.