Prognostic Factors and Longitudinal Change in Long-Term Outcome of Frontal Lobe Epilepsy Surgery

Abstract

We aimed to investigate the possible predictive factors and longitudinal change in long-term surgical outcome after refractory frontal lobe epilepsy surgery. We retrospectively reviewed 82 patients who underwent frontal lobe resection. Invasive monitoring was performed in 43 patients. All patients were followed-up for a minimum of 3 years after surgery. Univariate and multivariate analyses were used to evaluate the predictors. The Kaplan-Meier survival curve showed the estimated probability of complete seizure freedom, and a favorable outcome was defined as Engel class I at the last follow-up. The estimated probability of complete seizure freedom was 57.3% at 1 year postoperatively, 51.2% at 2 years, and 50.0% at 5 years. Factors predictive of worse long-term outcome were lack of a lesion in the frontal lobe on magnetic resonance imaging, generalized/nonlocalized ictal discharge, use of subdural grids, and acute postoperative seizure (APOS). After the surgery, 44 patients (53.7%) had seizures at any time during the first 2 years. Five of 44 patients had seizure freedom at the last follow-up. After a seizure-free period of at least 6 months, seizure recurred in 6 patients by 6 months to 1 year (early recurrence) and in 9 patients by 1-3 years (late recurrence). Eight of 43 (18.6%) seizure-free patients had discontinued drugs. The overall seizure outcome after surgery changed most during the first 2 years. The presence of frontal focal lesions and ictal frontal rhythm predicted favorable outcome. However, APOS was predictive of early epilepsy recurrence.