Surgical strategy in the management of low-grade brain neoplasm with epilepsy: seizure outcome

Background For 30-50% of patients with brain tumors, epileptic seizures are the presenting clinical sign of a tumor; 10-30% of patients develop seizures later during the disease course. Slow-growing tumors, (i.e. low-grade gliomata) are the most epileptogenic, although the high frequency of epilepsy in these patients might be related to longer survival from low-grade tumors. This study bears on this controversy through a prospective strategy in which patients were treated with excision of lesion together with epileptogenic area around, as defined using intraoperative electrocorticography. Patients and methods This is a prospective study designed to treat patients presenting between January 1997 and December 2011 with drug-resistant epilepsy (defined as failure to attain a seizurefree status utilizing adequate trials of two tolerated and appropriate antiepileptic drugs). Surgical procedure consisted of maximal resection of the tumor and any resectable surrounding associated with epileptogenic cortex, identified by means of intraoperative electrocorticography. Results Fifty-four patients were operated upon and followed up for a mean of 40 months (range = 6-72 months). Thirty-two tumors (59.2%) were located in the temporal lobe, 15 (27.8%) in the frontal lobe, and seven (13%) in the parietal lobe. The histopathology confirmed low-grade astrocytoma (WHO grade I or II) in 38.9% (n = 21) of patients, oligodendroglioma in 24% (n = 13), ganglioglioma in 20.4% (n = 11), and dysembryoplastic neuroepithelial tumor in 16.7% (n = 9) of patients. Gross total resection was achieved in 64.8% (n = 35) of patients and subtotal resection in 35.2% (n = 19) of patients. There was no death and five patients had permanent deficit. At follow-up, according to Engel's seizure outcome scale, 77.8% (n = 42) of the patients had good seizure control (classes I and II), and, collectively, 90.7% (n = 49) of patients had more than 75% reduction in seizures (class I-III). Conclusion In our series, we had a relatively high rate of gross total resection, which was associated with worthwhile seizure control, which compares favorably with a recent work that showed that the extent of resection significantly predicts seizure freedom following surgery. The favorable seizure outcome is tentatively attributed to the fact that all identified areas harboring epileptogenic activity around tumors were resected along with tumor resection.