Abstracts

Rationale: Focal cortical dysplasia is a common cause of treatment resistant epilepsy in children. In 2011, the International League against Epilepsy (ILAE) proposed a new classification system of FCD, adding FCD Type III which comprises the combination of FCD with tumor or mesial temporal lobe sclerosis (MTLS). We hypothesized that the outcome following surgery would be less favorable in children with FCD, particularly type III.Methods: The medical records of children who underwent temporal lobe surgery for treatment resistant focal epilepsy between 1990 and 2012 were reviewed. Patients who had progressive neurological disorders, such as Rasmussen s encephalitis, Tuberous Sclerosis Complex or multilobar resections were excluded. For those with FCD, the ILAE 2011 classification system was applied. Engel class I and II seizure outcome was classified as good and Engel class III and IV as poor.Results: The study population comprised 77 subjects, 39 males. Mean age at seizure onset was 6.2 years (range: 1 week 15 years) and mean age at surgery was 11.25 years (range: 4 months 19.2 years). The mean duration of follow up was 6.3 years (range: 1 18.7 years). Ten (12.98%) patients had febrile seizures. The pathological diagnosis was FCD in 31 (40%) subjects, with Type III being the most common (23 of 31), tumor in 31 (40%), MTLS alone in 10 (13%) subjects. Five children had other pathology : cavernoma (n=4) and meningiomatosis (n=1). 12 patients had more than 1 surgery, 7 (58%) of whom had FCD type III, 3 (25%) had a tumor, one patient had FCD type I and one had MTLS. Following the first resection, 19 (61%) of 31 children with FCD had a good outcome. Following further surgery in 8 of these patients (7 with Type III FCD), a total of 27 of 31 with FCD had a good outcome at most recent follow-up. 25 (80%) of 31 children with tumors had a good outcome following first surgery and following further surgery 28 (90%) had a good outcome. Seven (70%) of 10 children with MTLS had a good outcome following first surgery and following further surgery in one child, 8/10 had a good outcome. The children who had cavernomas or meningiomatosis were all seizure free following surgery.Conclusions: FCD and tumors were the most common pathological diagnoses in our study. FCD Type III was the most common type of FCD and re-operation was required in 26% of children with FCD. The final outcome following surgery was similar in all groups but the fact that re-operation was required supports the challenges in defining the extent of epileptogenicity in children with FCD.