Abstracts

Dysembryoplastic neuroepithelial tumor (DNT) is a benign brain tumor and often occurs in association with medically intractable partial seizures. The authors report our experience of DNT patients treated with epilepsy surgery., A retrospective review and analysis of medical records were performed on brain MRI findings, interictal and ictal EEG features pathological findings, other clinical characteristics, and surgical outcome of 14 patients with refractory epilepsy secondary to DNT., All patients showed cortical or subcortical lesions with T1 low and T2 high signal intensity, and only one case showed focal small enhancing portion within the tumor. Other MRI findings included cystic formation (6), calcification (2) and hippocampal atrophy (1). Temporal lobe was involved in 9 cases (64.3%), while frontal, parietal or occipital lobes were involved in 2, 3, and 1 respectively. Mean age at seizure onset was 7.2 years (range 0.3 - 13.8 years). All patients presented with complex partial seizures with or without secondary generalization, however, one patient had previous history of infantile spasms. Ten of the 12 patients revealed abnormal findings on interictal EEG. Long-term video-EEG monitoring (VEM) was done in 5 patients. The epileptogenic lobe was correctly localized by VEM in 4 patients who had lesions in the temporal lobe. Intracranial recording was performed in one patient, in whom lesion was located in the parietal lobe but scalp VEM failed to localize ictal onset zone. Lesionectomy was done in 8 cases (57%) and temporal lobectomy with amygdalohippocampectomy was done in 6 cases (43%). Pathology revealed associated cortical dysplasia (CD) in 4 patients (28.6%), and one of them showed oligodendroglioma component as well as CD. Mean follow-up period after surgery was 2.8 years (range 0.2 - 5.9 years). All had an Engel Class IA outcome (3 patients still have been on antiepileptic drugs) without recurrence of tumor. Second operation was performed in one patient with temporal lobe involvement. Postoperative morbidity (visual field defect and hemiparesis) was observed in 2 cases who had lesions in the temporal lobe (21.4%). Follow-up MRI could not exclude the possibility of residual tumor in 3 cases, however, no further seizure was reported so far. Six of the 9 patients showed normal postoperative EEG., DNT most frequently involved the temporal lobe and was often associated with CD. Gross total removal is thought to ensure favorable prognosis in most cases regardless of type of surgery. However, careful resection is necessary to reduce morbidity especially in case of temporal lobe involvement.,