Abstracts

Rationale: Focal Cortical Dysplasia (FCD) are abnormalities of cortical development and in most can cause medically refractory epilepsy requiring surgical resection. In some patients, the FCD can be located in deep locations such as the depth of a sulcus and electrocorticography (ECoG) maybe more challenging. We retrospectively reviewed patients with confirmed FCD by pathology with deep locations who underwent FCD resection ECoG guided. We looked if ECoG helped during the resection and if it affected surgical outcome.Methods: We identified patients from our epilepsy surgery database from 2011- 2014 who had FCD with a deep location resected electrocorticography guided. Only patients with follow up of more than 6 months post resection were included. The database and medical records were queried for demographics, seizure type, video EEG, MRI, Engle outcome, morbidity and complications.Results: Thirteen patients were identified to have deep FCD and 10 had electrocorticorgraphy guided resection. Age ranged from 9 months to 15 years and seizure onset was at 2 months to 7 years. All had focal epilepsy and all had daily to multiple seizures per day and failed more than 2 appropriate seizure medications. All the EEG/video EEG were concordant to the area of the FCD. MRI showed FCD in all patients except for 1 patient that was initially read as “normal”. One initially had a normal MRI and then after 2 years of age the FCD became more apparent. All the FCD were seen in extratemporal locations with the following distribution: occipital (1), parietal (2), insular (3), frontal (4). Nine had resections with ECoG and 1 had an initial grid (for language and mapping) followed later by additional resection with ECoG due to recurrence of seizures. Three relapsed post resection and required repeat surgery (in one, the FCD was near an eloquent cortex which limited the resection). Seven (70%) had Engel 1 surgical outcome (free of disabling seizures). Two had Engel 1-2 outcome initially and then the seizure relapsed and after repeat resection ECoG guided, they became Engel 1. One had an Engel 4 but on repeat resection with ECoG became Engel 1. Follow up MRI showed residual dysplasia on all 3. In all of those that had ECoG, the ECoG was helpful in showing spikes or seizures where the expected dysplasia was and showed resolution of the spikes post resection. In one of the patients that required a repeat resection, the residual dysplasia was at the inferior and deepest aspect of the resection cavity which limited placement of the depth electrodes and the ECoG was not informative. Complications were seen in 2 patients and included transient one sided weakness. Pathology included Type 1a (6), Type 1b (1), and type 2b (3).Conclusions: The study shows that good surgical outcome can be achieved with resection of deep focal cortical dysplasia in children. Although grid and depth placement to deep focal dysplasia during resection maybe more challenging, our study showed that doing ECoG was still helpful.