Abstracts

Proper time, extent, and prognosis of Epilepsy surgery for low grade tumor are not established. This study is aimed at investigation of the surgical outcome and the prognostic factors of epilepsy patients with a brain tumor. We acquired the data from the epilepsy surgery cohort since May 1995. Inclusion criteria were as follows: patients who had 1) a hemispheric intra-axial neuroepithelial tumor, 2) seizure as an only presenting feature, 3) no neurological deficit at presentation, 4) at least 1 year of follow-up after surgery. We excluded highly malignant tumors (world health organization grade IV). We evaluated the seizure outcome according to Engel[apos]s classification. The degree of resection was assessed on postoperative magnetic resonance imaging (MRI). 75 patients fulfilled the criteria. Median follow-up was 3.3 years (range 1.0-9.3 years). Ganglioglioma (25 cases) was the most common histopathological entity and dysembryoplastic neuroepithelial tumor (18 cases), oligodendroglioma (13 cases) and diffuse astrocytoma (6 cases) followed. Eight cases of world health organization (WHO) grade III tumors were included.
One year after surgery, 77.3% of the patients were seizure-free (class I). Overall seizure-free rate at last follow-up rose up to 85.7% and 72% of those patients were free of anticonvulsants. Favorable seizure outcome was associated with the degree of resection, pathological grade, tumor location that required awake anesthesia, intractability and EEG concordance in univariate analysis. Among theses factors, only degree of resection and pathological grade gained statistical significance in multivariate analysis (p=0.023, 0.020 respectively).
Concomitant hippocampal sclerosis (dual pathology) was found in 9 patients (12%). Resection of both the tumor and mesial structures yielded better outcome than resection of the tumor alone (p=0.048). Degree of surgical resection and pathological grade of the tumor are the most important factors for seizure outcome in epileptic patients with a brain tumor. In the case of dual pathology, both the tumor and mesial structures should be resected for better seizure outcome.