Abstracts

Rationale: Focal cortical dysplasia (FCD) and hemimegalencephaly (HMEG) are malformations of cortical development (MCD), both important causes of intractable childhood epilepsy. We aimed to determine the association of clinical features and volume measurement among FCD and HMEG in intractable childhood epilepsy who underwent epilepsy surgery Methods: Retrospective study of patients with cortical malformation (CM) including FCD and HMEG through the pediatric epilepsy surgery program database at Children’s National Medical Center between January 1, 2009 – December 31, 2016. We reviewed charts for clinical data, therapeutic interventions, MRI, for both FCD and HMEG groups. All patients underwent resective surgery and were confirmed by histopathology. MCD volumes determined by an ROI approach of hand-draw masks from 1.5T and 3T MRI T2 and T1 SPGR images; in addition to estimate the volume of the lesion, lesion locations were identified by from the ROI center of mass was normalizing the MRI images along with MCD masks co-registered in to common MNI space. Brain volume was also calculated and the proportion of the MCD volume over brain size were also used to control for brain size differences.  The data were analyzed by descriptive statistics, Mann-Whitney U-test, and Fisher’s exact test, as appropriate Results: Sixty-two patients were identified: 55 with FCD (29 males) and 7 with HMEG (6 males). Median age of seizure onset was 18.96 months (range 0.02 months to 16.0 years) in the FCD group and median age of seizure onset was 0.24 months (range 0.04 to 4.92 months) in HMEG group (p = 0.0005). Median age of surgery was 7.84 years in FCD group (range 2.89 months to 24.45 years) versus 5.92 months in HMEG group (range 4.0 to 56.0 months). We found CM in FCD was located frontal 21 (38.18%), temporal 15 (27.27%), parietal 10 (18.18%), and occipital 3 (5.45%) or was multilobar 6 (10.91%) while HMEG involves approximately 60-80% of the hemisphere assessed. In the FCD group, 45.5% occurred in the left hemisphere whereas 85.7% in HMEG occurred in the left side. In the FCD group with age of seizure onset 3 (range: 0.87 to 342.49 cm3) in FCD and 395.16 cm3 (range 227.66 to 722.29 cm3) in HMEG group (p < 0.0001) Conclusions: HMEG is more predominant in males and in the left hemisphere. HMEG is associated with earlier onset of seizures and younger age of surgery. FCD seizure onset before one year old is more likely to arise from a frontal location, while seizure onset after age 5, occurs more often in the temporal regions –observations that may reflect brain maturation or regional differences in clinical symptoms with seizures Funding: None