P14.34 Long-term seizure outcomes and tumor recurrence after glioneural tumor surgery: A single-center retrospective cohort

Abstract

Abstract BACKGROUND Gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNET) are glioneural tumors associated with treatment refractory seizures, especially in younger patients. Because there is a relative paucity of data on which factors predispose patients for recurrences, we analyzed our own cohort treated over the last 25 years. MATERIAL AND METHODS We performed a retrospective analysis of all patients undergoing resection of a glioneural tumor with a minimum follow up of one year. Surgery type, histological findings, and seizure outcome were extracted from patient records. Recurrence was defined as new tumor lesions in previously unremarkable parenchyma or tumor growth of a residual lesion. We performed a Mann-Whitney-U test to determine statistical significance of differences in continuous variables and Fisher’s exact test in categorical. RESULTS In total, 109 patients were operated between March 1994 to March and followed for a median of 62.4 months (range 12–281 months). The average age of patients at the time of surgery was 21.2 years with 60 patients belonging to the pediatric population. Complete lesionectomies were the goal in 72 cases, extended resections in 10, and partial resection due to proximity of eloquent areas was performed in 27 cases. 77 tumors were classified histologically as a GG and 32 as a DNET. The temporal lobe was the most common site of origin with 65 tumors (59.6%) being found there. On postoperative MRI, complete resection was achieved in 76 cases. Local tumor recurrences were seen in 14 patients (12 GG and 2 DNET), 9 of which occurred in patients with apparently complete resection. Overall, only one malignant transformation of a GG was observed. Age at surgery was significantly lower for patients with later recurrence (11.9 yrs vs. 22.6 yrs for patients without recurrence, p=0.0047). A second surgery was performed in 11 patients with previously incomplete resections (33%) and 7 patients with complete resection (9.2%), p=0.0038. 95 patients (87.2%) had preoperative seizures for a median of 26 months before surgery. One year after surgery, a documented ILAE outcome was available for 90 of these patients and 63 (70%) were seizure free one year after surgery. While 45 patients with epilepsy (47.4%) had at least one seizure relapse after surgery - most often associated with AED withdrawal or tumor recurrence - medical therapy and repeat resection allowed 76 patients (80%) to be seizure free for over one year at their last follow up. Age at surgery was not a significant predictor of seizure freedom. CONCLUSION Glioneural tumors are highly epileptogenic but neurosurgical resection allows seizure freedom in the large majority of these patients. Tumor recurrences were more likely in younger patients and incomplete resections predisposed patients to need another surgery. Resection extent on MRI does not appear to be a reliable marker for future recurrence risk.