Abstracts

Rationale: Children with medically refractory epilepsy caused by focal cortical dysplasia (FCD) often require surgical intervention. Intraoperative MRI (iMRI) assisted resection may allow a more complete removal of abnormal brain tissue improving seizure outcomes. Methods: We retrospectively identified patient who underwent iMRI assisted resection from January 2014 to July 2016 with at least 6 month follow up post op. The database was queried for demographics, iMRI, pathology, Engel outcome, morbidity and complications. Results: A total of 28 patients underwent FCD resection at our center. Seventeen underwent resection assisted with iMRI. Age ranged from 3.1 to 21 years old (10 female and 7 male). All patients had focal seizures. The location of the FCDs were temporal (1), insular (2), frontal (7), and parietal (7). Five out of 17 were repeat surgeries. Twelve out of 17 (64%) had Engel 1 outcome . Three patients had previous surgery. The location of the FCD were temporal (1), insular (2), frontal (4), and parietal (5). During intraop, eight patients had an apparent total gross resection of the FCD on iMRI. In four patients, however, the iMRI suggested residual dysplasisa and 3 had further resections. Pathology showed Type IIA (8), Type IIB (3), Type I (1) Three (23%) had Engel 2 outcome. The location of the FCD were frontal (2), and parietal (1). All three had apparent total gross resection of FCD on iMRI. Pathology showed Type IIA (1), Type IIB (1), Type IB (1)Two (11%) had Engel 3 outcome. These two were repeat surgeries. One had an apparent total gross resection of the FCD on iMRI but relapsed 6 months post op. Follow up MRI showed residual dysplasia. His pathology was undetermined. One patient had possible residual by iMRI, but no abnormalities were seen in the OR. She was initially seizure free for 2 years. Although no obvious residual dysplasia was seen in the MRI, the location of the previous dysplasia was at the bottom of the sulcus and was in an eloquent cortex. Pathology was type IIB. Location was parietal (1) and frontal (1). Post resection complications included transient or minimal extremity weakness (2) and transient hallucinations (1). Conclusions: Our findings support that the use of iMRI allows for complete resection of FCD and improve seizure outcome. The near real time complete resection provided by the iMRI showed in majority, seizure freedom and reduced need for reoperation. Location of FCD, previous surgery and pathology did not consistently seem to impact the likelihood of a complete resection although our numbers were limited. Minimal or expected neurologic deficits were seen in a few.