Glioneuronal tumors and medically intractable epilepsy: a clinical study with long-term follow-up of seizure outcome after surgery.

The present study intends to identify factors that predict postoperative clinical outcome in patients with gangliogliomas (GG) and dysembryoplastic neuroepithelial tumors (DNT). We evaluated the medical records of 45 patients with GG and 13 patients with DNT, treated surgically between 1985 and 1995. We assessed several clinical and histopathological features and analyzed the data statistically. At 5 years postoperatively, 63% of patients with GG and 58% of patients with DNT were seizure-free (Engel's class I). Younger age at surgery (P<0.01 for GG and P<0.05 for DNT), total resection (P<0.01 for GG), shorter duration of epilepsy (P<0.01), absence of generalized seizures (P<0.01 for GG; P<0.05 for DNT) and absence of epileptiform discharge in the post-operative EEG (P<0.01 for GG; P=0.01 for DNT) predicted a better postoperative seizure outcome. Tumor recurrence with malignant progression occurred in eight histologically benign GG and two anaplastic GG and was associated which older age at surgery (P=0.01) and subtotal resection of the tumor (P<0.01). Our results indicate that a prompt diagnosis, relatively soon after seizure onset, followed by complete resection of glioneuronal tumors provides the best chance for curing epilepsy and preventing their malignant transformation.