Towards a better definition of a resection strategy in pediatric LEATs causing refractory epilepsy

Abstract-Text (inklusive Referenzen und Bildunterschriften)

Objective: Resection strategy in pediatric long-term epilepsy associated tumors (LEATS) consists of pure lesionectomy, ECoG guided tailored resection or even partial/complete lobectomy. To propose an evidence based appropriate surgical strategy, we retrospectively analysed our consecutive institutional series of surgically treated pediatric LEATs.

Methods: Twenty-two children suffering from medically intractable seizures harbouring suspected LEATs were investigated at the pediatric epilepsy monitoring unit using clinical and video EEG monitoring, extended MRI epilepsy protocol and FDG and Methionine (MET) PET examinations. Additionally, 2 stereo-EEGs were performed. In 17/22 patients ECoG was used for intraoperative pre-and postresection EEG assessment and when feasible for tailoring the amount of resection. Additionally, neuronavigation and intraoperative MR imaging in recent cases were used for guiding the surgery.

Results: All children (mean age 8 yrs, from 2-18) were consecutively resected during a 3 years period. Lesions were located in the temporal lobe in 15 patients and extra-temporally in 7 patients (2 parietal, 3 frontal and 2 occipital). In temporal LEATS, mainly antero-temporal resections or temporal lobectomies were performed (15 patients), whereas in extratemporal LEATS lesionectomies or tailored resections guided by ECoG were achieved (7 patients). Histological diagnosis was GG in 20 and DNET in 2 patients. Preoperative MRI contrast enhancement was present in 10 GG (45%) and FDG PET showed a hypo-metabolic area in 6 GG (27%). Intensiv Methionine (MET) PET uptake was found in 13 GG, weak MET enhancement in 6 GG and no tracer uptake in 1 GG. One DNET showed MET PET uptake, the second one did not. However, MET PET uptake did not correlate neither with MR contrast uptake intensity, nor with extent of the tumor defined by FLAIR images. Thus, diagnostic sensitivity of MET PET for GG was 100%, specificity 95% in our patients. In temporal resections, ILAE Class 1 seizure outcome was achieved in 75%, which was improved to ILAE Class 1 in 94% by performing 6 repeat surgeries with antero-temporal lobectomies after unsuccessful lesionectomies. The extratemporal patients experienced ILAE Class 1 seizure outcome in 86% without additional surgeries (mean follow-up 28 month).

Conclusion: In childhood LEATs amino acid PET was found to have high diagnostic sensitivity for GGs. In surgical therapy, for extratemporal LEATs a pure lesionectomy or tailored resection may be an appropriate strategy. On the contrary, for temporally located LEATs an antero-temporal resection or even temporal lobectomy may be necessary to achieve seizure freedom and avoid recurrences.