Abstracts

Rationale: Neurodevelopmental tumors (such as dysembryoplastic neuroepithelial tumors (DNET) and gangliogliomas) have until now been described as being generally associated with pharmacoresistant epilepsy. These tumors share some common features (such as young age of onset of epilepsy, benign evolution, and certain radiological particularities). We performed a clinical and neuroradiological study to demonstrate that epilepsy related to such neurodevelopmental tumors is not always pharmacoresistant, and does not always need surgical treatment.Methods: We included in our retrospective study 69 patients with symptomatic focal epilepsy, pharmacoresistant or not, in whom neuroradiological findings suggested neurodevelopmental lesions. This diagnosis was considered as “possible” when concordant diagnosis was made by two independent blinded neuroradiologists. We compared “operated” and “non-operated” patients in terms of the clinical course of epilepsy (age of seizure onset and seizure frequency), emphasizing the degree of pharmacoresistance. We looked for clinical and/or radiological features that might differ in the two groups, and that may predict anti-epileptic drug (AED) responsiveness.Results: Of these 69 patients, the diagnosis of neurodevelopmental tumor was assessed as “possible” in 58. In this group, 33 patients (56.8%) had undergone surgery (lesionectomy, cortectomy or lobectomy) and neuropathological examination confirmed the diagnosis of neurodevelopmental tumor. This suggested that non-operated patients also presented epilepsy related to neurodevelopmental tumors. In the group of 58 neuroradiologically confirmed neurodevelopmental tumors (comprising 60 lesions since 2 patients had a second identical tumor), these were located within temporal lobe (71%), frontal lobe (13.3%), parietal lobe (6.6%), or in other areas (9%). In the “operated” group (33 patients), the mean age at epilepsy onset was 13.5 years; duration of epilepsy was 12.3 years and the M/F sex ratio 0.73. Most patients (85%) had seizures every day or several times per week, while only 15 % had only a few seizures per month, showing that, from the onset, epilepsy was pharmacoresistant. Neuropathological results found 82% DNET (simple 3.9%, complex 38.4 %, and non-specific form 57.7%) and 12% gangliogliomas (2 histopathological results were unavailable). In the “non-operated” group (25 patients), mean age at epilepsy onset was 19 years ; duration of epilepsy was 11.7 years and M/F sex ratio 2.6. In 64% of cases the epilepsy was AED responsive at onset, with patients presenting only a few seizures on average per month and 84% being seizure-free at follow up. Conclusions: This retrospective study suggests that epilepsy related to neurodevelopmental tumors is not always pharmacoresistant. In the group of operated patients, it seems that epilepsy tends to present at a younger age, with very frequent seizures from onset. Later onset of epilepsy, with less frequent seizures seems to be characteristic of the second group, which had an over-representation of men.