Epilepsy surgery in Neurofibromatosis Type 1

Epilepsy is relatively uncommon in patients with Neurofibromatosis Type 1 (NF1) and seizures are usually well controlled with antiepileptic treatment. However, pharmacoresistance has been reported in patients with NF1 and MRI evidence of malformations of cortical development or glioneuronal tumours. Available information on epilepsy surgery in NF1 is limited to a few patients with gliomas and glioneuronal tumours who underwent lesionectomies. We conducted a survey amongst 25 European epilepsy surgery centres to collect patients with NF1 who had undergone surgery for drug-resistant seizures and identified 12 patients from eight centres. MRI abnormalities were present in all patients but one. They were unilateral temporal in eight, bilateral temporal in one and multilobar or hemispheric in two. Seizures originated from the temporal lobe in ten patients, from the temporo-parieto-occipital region in one, and were bitemporal in one. One year after surgery eight patients were seizure free, one had worthwhile improvement and the remaining three had experienced no benefit. Postoperative outcome, available at 2 years in ten patients and at 5 years in three, remained stable in all but one whose seizures reappeared. Histology revealed dysembryoplastic neuroepithelial tumour (DNET) in five patients, hippocampal sclerosis in four, mixed pathology in one and polymicrogyria in one. No histological abnormality was observed in the remaining patient. Epilepsy surgery can be performed effectively in patients with NF1 provided a single and well-delimited epileptogenic zone is recognized. The high prevalence of DNETs in this series might suggest a non-fortuitous association with NF1.