Abstracts

Rationale: Despite growing evidence favoring early surgical intervention in patients with treatment resistant epilepsy, surgical management remains underutilized. We introduced and validated the Epilepsy Surgery Grading Scale at our comprehensive epilepsy center as a novel means to stratify a patient’s likelihood to derive benefit from epilepsy surgery based on easily available data (MRI, EEG, and concordance categories). Patients were categorized as Grade 1 (expected to be the most favorable candidates; most likely to proceed to resective epilepsy surgery and become seizure-free as a result), Grade 2 (intermediate candidates), and Grade 3 (least favorable candidates). In this retrospective analysis of the most successful (Grade 1) and the least successful (Grade 3) surgical patients, we sought to evaluate the utility of ESGS in predicting the probability of seizure relapse after 1 year of seizure freedom.   Methods: This was a retrospective study which included patients who were admitted to the NYU adult epilepsy monitoring unit (EMU) for a presurgical evaluation or were presented for discussion at surgical multi-disciplinary conference at NYU between 1/1/2007 and 7/31/2008. We required that patients were >18 years of age, had a diagnosis of focal epilepsy for ≥2 years, had failed ≥1 medication, and had ≥1 seizure in the 3 months prior to admission.  Achievement of a period of 12 consecutive months of seizure freedom after surgery was assessed within both Grade 1 and Grade 3 patients. After 12 months of seizure freedom, relapse versus continued seizure freedom over subsequent follow up at the study’s conclusion (July 31, 2017) was assessed to examine relapse rates.    Results: Of the Grade 1 patients who experienced a 12-month period of seizure freedom, 21/27 (77.7%; 95% CI (47.94-95.41)) went on to experience sustained seizure freedom compared to 2/10 (20%; 95% CI (10.26-41.1) of Grade 3 patients (p=0.045).    Conclusions: Rate of late relapse in both excellent (Grade 1) and suboptimal (Grade 3) surgical candidates can be predicted by pre-surgical characteristics that are easy to identify and are captured by the Epilepsy Surgery Grading Scale. Grade 1 patient were likely to experience enduring seizure freedom and Grade 3 patients had a higher rate of seizure recurrence. Adoption of this grading scale would facilitate conversation with our patients, streamline surgical categorization, and better manage patient expectations during surgical epilepsy evaluation.  Funding: No funding