Abstracts

Rationale: Next to patients with temporal lobe epilepsy (TLE), those with frontal lobe epilepsies (FLE) are candidates most likely benefitting for epilepsy surgery. Non-invasive source localization may offer additive and non-redundant information during presurgical investigations. A number of clinical studies with short-term follow up indicate its value, however detailed analysis of the localization of focal epileptic activity in relation to epileptic lesions and preservation of function with long-term follow-up are missing.Methods: 46 patients with pharmacoresistant FLE surgery (28 male patients) and presurgical evaluation including MEG, MRI and neuropsychology etc., were analyzed retrospectively with a mean follow-up of 5 years. Dipole and sLoreta analysis were performed for MEG localization. The mean age at first seizure manifestation was 14 years, the mean age at surgery was 30 years. Results: 1. Focal epileptic activity was found in 82.6% patients (monofocal activity 81.6% vs. multifocal activity 18.4%). 67.7% patients of the monofocal activity were within the resection volume. Of these, 85.7% patients had Engel class I outcome, which comparing to 42.9% in partial resection and 33.3% in the non-resected group, was statistically significant (p 0.001). 2. Seizure freedom in patients with monofocal MEG findings was statistically significantly more frequent than in patients with multifocal localizations (p=0.018). 3. In case of surgery in the dominant hemisphere, seizure control was less likely (p=0.005). 4. FCD II, DNT and meningioma correlated predominantly with monofocal activity and postoperative seizure control.Conclusions: The data indicate that source localization may contribute to the prediction of postoperative outcome in FLE patients. With regards to a long latency of 16 years between first seizure and later surgery, source localization may contribute to shortcut the route from diagnosis to surgery. This study was supported by DFG STE 380/14-1 and STE 380/15-1