Long-term seizure outcomes after extended resection of low-grade epilepsy-associated neuroepithelial tumors.

Although most patients with low-grade epilepsy-associated neuroepithelial tumors (LEATs) achieve satisfactory long-term postoperative seizure control, optimal surgical strategies remain undefined. We employed subdural electrode implantation and extended resection, including the tumor and surrounding cortices, in patients with LEATs to assess whether this approach improved seizure outcomes over a 10-year postoperative follow-up. Forty-five patients (26 men, 19 women) who underwent LEAT removal, with ≥2 years of follow-up, were included, and 34 (75.6%) showed temporal lobe tumors. In 30 (66.7%) patients, intracranial subdural electrodes were implanted, and video electroencephalography was performed. Seizure outcomes were classified using the International League Against Epilepsy (ILAE) criteria. Clinical variables independently associated with seizure-free (ILAE class I and Ia) outcomes were determined using univariate and multivariate analyses. The median postoperative follow-up was 117.6 (range, 24-319) months. At the final follow-up, 36 (80.0%) of 45 patients were seizure-free. Although 62.2% patients were seizure-free (ILAE class I and Ia) 1 year after surgery, the 4- and 5-year seizure-free rates were significantly higher; this indicated a running-down phenomenon. Univariate analysis showed significantly higher seizure-free rates for patients with temporal lobe tumors than for those with extra-temporal lobe tumors. Multivariate analysis confirmed tumor location as the only variable significantly correlated with seizure outcomes. Extended resection of the LEAT and surrounding tissue resulted in an 80% seizure-free rate at an average of 10 years after surgery. Outcomes were more favorable for temporal than for extra-temporal lobe tumors. Patients with LEATs may experience a running-down phenomenon for several years postoperatively.