Abstracts

RATIONALE:_Dysembryoplastic Neuroepithelial Tumor (DNT) are a group of glioneuronal supratentorial and intracortical lesions associated often with medically intractable seizures. There are characterized by location, multinodular architecture and heterogeneous glioneuronal cellular composition. Two histopathological types of DNT's have been described: a circumscribed simple form, with a glial component and specific glioneuronal element, and a extended complex form, with, in association, foci of cortical dysplasia. Differentiation between those two DNT's types is not always easy on CT and MRI. Substraction of ictal and interictal SPECT images co-registrated to 3D MRI (SISCOM) improves the realibility and clinical usefulness in defining epileptogenic zone. The aim of this study is to determine if SISCOM in temporal lobe epilepsy help to differentiate "simple" and "complex" types of DNT. METHODS: We studied seven patients (3 women, 4 men, mean age 21) with refractory temporal lobe epilepsy, related to DNT located in temporal lobe. Presurgical investigations included video-EEG recordings, neuroimaging (CT, MRI) and SISCOM (software: MEDIMAX). RESULTS: SISCOM showed two distinct patterns: a circumscribed hyperperfusion, coincident with neuroimaging abnormalities; a widespread hyperperfusion involving all temporal structures, including areas without significant defects evident on neuroimaging. Histological examination showed a "simple" form of DNT in two cases, and a "complex" form in five cases. SISCOM results agree with the histopatological findings (two cases of simple form, and five case of complex form of DNT s). No recurrence of seizures has been observed in the post-surgical follow-up (median 1 year). CONCLUSIONS: These preliminary data suggest that SISCOM contributes to distinction between "simple" and "complex" form of DNT s. Concordance of: symptomatogenic zone, MRI findings, SISCOM pattern, complete DNT surgical removal; was predictive of a good post-surgical outcome. SISCOM use among pre-surgical investigations might have a role in decision of the surgical strategy in DNT's.