Abstracts

Rationale: In patients with refractory focal epilepsy, surgery remains an important treatment option for achieving seizure freedom. However, the existing data suggest that for patients with normal neuroimaging, the likelihood of achieving seizure freedom is significantly reduced compared to patients with lesional neuroimaging. This study assesses the utilization of resective surgery versus medical management in patients with normal neuroimaging. Specifically, the study aims to determine how frequently patients with normal brain MRIs are referred for epilepsy surgery and whether there is a difference in outcome (i.e. seizure control) between medically managed and surgically managed patients. Methods: Following approval through the Institutional Review Board at New York University School of Medicine, patients were retrospectively identified by querying the surgical multidisciplinary case (MDC) conference registry. The records were reviewed from January 1, 2007 - July 31, 2008 to identify patients. Inclusion criteria were: age ?18 years, focal epilepsy diagnosis ?2 years, failed ?1 medication, and ?1 seizure three months prior to admission. Of all patients meeting these criteria, 193 were presented at the MDC conference and 33 had normal MRIs upon review. Seizure frequency data were collected by chart review, and when data were incomplete, the patient s primary epileptologist at the NYU Comprehensive Epilepsy Center was contacted. Comparisons were made between the two groups (surgical versus nonsurgical treatment) utilizing the Student s t-test and Fisher s exact test.Results: Of the 33 patients with normal neuroimaging who were presented at MDC, 19 went on to epilepsy surgery (9 women) and 14 were managed medically (7 women); all patients undergoing invasive monitoring underwent resective surgery. The mean age at the time of MDC did not differ between groups (surgery: 30.1 10.4, medical: 29 10.6; p>0.76). Although a trend for a younger mean age at seizure onset was seen for medically managed patients (surgery: 16.6 9.3, medical: 10.9 8.8; p>0.09), no significant difference was seen for duration (in years) of epilepsy at the time of MDC (surgery: 13.6 10.2, medical: 18.1 12.5; p>0.26). At the time of last follow-up, 7 (36.8%) surgical patients were seizure free and 3 (21.4%) medically managed patients were seizure free (p=0.46).Conclusions: Across one and a half years, only 33 of 193 (17.1%) patients reviewed at MDC had normal neuroimaging and focal epilepsy. Ten (30.3%) of the 33 patients were completely seizure free (Engel IA) at last follow-up (with either medical or surgical management). Nineteen of the patients with normal neuroimaging went on to resective surgery with seven (36.8%) becoming seizure free, whereas three (21.4%) of the 14 who were managed medically became seizure free. These data demonstrate that patients with normal neuroimaging represent a minority of those presented at MDC. Although not seen in the majority of cases with normal neuroimaging, seizure freedom can be achieved through either surgical or medical management.