Abstracts

Rationale: Attention has traditionally been focused on the potential negative implications of long epilepsy duration prior to temporal lobe epilepsy surgery, but little is known about this question outside of the temporal lobe. Here, we investigate whether seizure outcomes following resective surgery for medically intractable frontal lobe epilepsy (FLE) also differ depending on age and disease duration. Methods: We reviewed patients undergoing FLE surgery for medically intractable epilepsy from January 1995 to October 2010 at Cleveland Clinic. At least 6 months of follow-up were required. Traditional seizure outcome determinants were collected and results were analyzed using Cox-proportional hazard modeling controlling for surgical technique and extent of resection. Results: 158 patients fulfilled study criteria and were analyzed. Half were children, and 53% were male. As expected with FLE surgery, etiology was a major outcome determinant with tumor cases having the highest rates of seizure-freedom (73% seizure-free at 5 years and beyond) and stroke and malformations of cortical development having the worst results (14% and 41% respectively seizure-free at 5 years). Other expected outcome determinants were:1)- side of surgery (higher rates of seizure-freedom with nondominant resections; p=0.02), and 2)- and presence of acute postoperative seizures (p-value<0.0001). On univariate analysis, age was also a significant seizure outcome determinant: 69% of children were seizure-free at 1 year, 64% at 2 years, 52% at 5 years and beyond as opposed to 60% of adults at 1 year, 49% at 2 years, and 26% at 5 years and beyond (p=0.01), as was epilepsy duration with 64% seizure-free at 10 years if operated with less than 5 years epilepsy duration as opposed to 19% otherwise at the same time-point (p=0.0004). Following multivariate analysis, the following independent outcome predictors retained significance: epilepsy duration, side of surgery and presence of acute postoperative seizures (Whole model Log-Rank test <0.0001). In addition, there was a tendency for earlier seizure recurrences in patients with longer epilepsy duration (p=0.06). Conclusions: This study suggests a possible epileptogenic effect of prolonged disease duration and recurrent seizures with extratemporal lobe epilepsy. The findings provide preliminary data to encourage and support a more aggressive and earlier practice of resective epilepsy surgery in medically intractable FLE patients.