Frequent association of cortical dysplasia in dysembryoplastic neuroepithelial tumor treated by epilepsy surgery

Background: We report on our experience with epilepsy surgery in the treatment of localization-related epilepsy caused by dysembryoplastic neuroepithelial tumor (DNT) aimed at achieving the best seizure control. Methods: A retrospective analysis was performed on the pathological reports as well as on clinical data of 24 case patients with medically intractable epilepsy with DNT treated surgically between 1995 and 2000 at the Samsung Medical Center. Resective surgery was performed using subdural electrodes or intraoperative electrocorticography in all patients. Results: The mean follow-up period was 57.2 months. Two patients had rare seizures transiently after surgery but remained free from seizures after 6 months. Others remained completely free from seizures. There was a strong tendency of temporal lobe involvement (19 cases; 79.2%). Size of tumors located at medial temporal regions was significantly smaller than those at lateral temporal or frontal lobes (P < .05). A rather radical resection (tumor plus surrounding tissue showing active epileptogenicity) was performed in all but one case where only focal lesionectomy was done. In 20 of the 24 cases (83.3%), association of cortical dysplasia (CD) was found on pathological examination. Conclusions: We conclude that DNT is frequently associated with CD, with a wide area of epileptogenic activity that might be related to the presence of CD around the DNT. Comprehensive preoperative investigations for accurate localization of epileptogenic activity, meticulous brain mapping, and a rather radical resection of pathological areas might be essential for the achievement of excellent seizure control in DNT-associated epilepsy.