Surgical outcomes and seizure control rates after resection of dysembryoplastic neuroepithelial tumors.

Object: In this study the authors review the outcomes in pediatric patients who presented with seizures and underwent resection of dysembryoplastic neuroepithelial tumors (DNETs). The authors focus on the diagnostic evaluation and surgical techniques that facilitate gross-total tumor resection and subsequent freedom from seizures.

Methods: Eighteen patients between the ages of 1 month and 13 years who presented with seizures underwent resection of DNETs between January 1992 and December 2004. Preoperative evaluation included magnetic resonance (MR) imaging and interictal scalp electroencephalography (EEG) in all patients, functional MR imaging in eight patients, video monitoring with ictal scalp EEG in 12 patients, interictal single-photon emission computerized tomography (SPECT) scanning in one patient, and ictal SPECT scanning in two patients. Thirteen patients underwent one-stage procedures, whereas five underwent two-stage procedures (implantation of monitoring electrodes followed by tumor resection), either for functional language mapping (three patients) or due to inconclusive preoperative data (two patients). Intraoperative electrocorticography (ECoG) was performed in 17 patients and led to resection of the cerebral cortex beyond the tumor margins in 10 of them. According to operative reports, gross-total tumor resections were achieved in all patients, but one child had minimal residual tumor on postoperative MR images that has remained stable. The only surgical complication was a transient third cranial nerve palsy. Over a median follow-up duration of 1.6 years, all patients are seizure free and without radiographically detected tumor recurrence.

Conclusions: Dysembryoplastic neuroepithelial tumors are a highly treatable cause of epilepsy in children. Excellent rates of complete tumor resection and seizure control with minimal morbidity can be attained using intraoperative ECoG and two-stage surgical procedures when appropriate.