Abstracts

Rationale: Focal Cortical Dysplasia (FCD) is a common cause of intractable epilepsy in children. Seizure freedom following resection of FCD is determined by complete resection of the dysplastic cortical tissue. However, difficulty with intraoperative identification of the FCD lesion may limit the ability to achieve the surgical objective of complete extirpation of these lesions. The use of intraoperative magnetic resonance imaging (iMRI) may aid in real time detection of these lesions and improve seizure control outcomes compared to traditional resective surgery.Methods: We retrospectively reviewed the medical records of pediatric subjects who underwent surgical resection of FCD at Children’s National Medical Center between March 2005 and April 2014. Subjects were grouped into two categories depending on whether iMRI was employed at surgery. Post-surgical seizure outcome was assessed utilizing the Engel Epilepsy Surgery Outcome Scale.Results: 12 consecutive patients (8 females and 4 males) with intractable FCD who underwent iMRI assisted FCD resective surgery were compared with 41 consecutive control patients (15 females and 26 males) who underwent standard resection without iMRI. The median age in the iMRI assisted resection group at the time of surgery was 8 years (range 0.7 to 18.8 years), median age at seizure onset was 0.9 years (0.04 to 9 years), and the mean duration of follow up was 2.2 months (SEM: 0.6 months). The median age in the control resection group at the time of surgery was 6.3 years (range 0.14 to 18.91 years), median age at seizure onset was 2 years (range 0.6 to 6 years), and the mean duration of follow up was 27.3 months (SEM: 3.5 months). IMRI assisted resection resulted in a 30% increase in OR duration over the controls from 288 minutes (SEM 9.2 minutes) to 373 minutes (SEM 2.9 minutes). At the time of the last postoperative follow up, 11 of the 12 patients (92%) in the iMRI resection group were seizure free (Engel Class I), compared to 18 of the 41 patients (44%) in the control resection group (p = 0.0033, Fisher’s exact test). 11 of 12 patients (92%) in the iMRI group were confirmed to have a complete resection of dysplastic tissue by iMRI analysis, while post-operative MRI confirmed complete resection in 25 of 41 patients (61%) in the control group (p = 0.0429, FET). There were no patients from the iMRI assisted resection group requiring reoperation, compared to 12 of the 41 patients (29%) in the control resection group (p = 0.0296, FET).Conclusions: Our results suggest that the utilization of iMRI during surgery for resection of FCD results in improved post-operative seizure freedom, completeness of lesion resection and reduction in the need for reoperation.