gms | German Medical Science

Objective: Long-term epilepsy associated tumors (LEATs) are a heterogenous group of mostly benign tumors which are typically associated with drug-resistant epilepsy. The aim of the present study was to analyse the epileptological and functional outcomes in patients with pharmacoresistant epilepsy, who underwent surgical resection of LEATs.

Methods: This retrospective single-center study comprises 186 consecutive patients, who underwent resective surgery for LEAT. CD-34 status was assessed by immunohistochemistry. Preoperative diagnostic modalities, surgical treatment, histopathological evaluation, and clinical as well as epileptological outcome were analyzed. Functional outcome was measured using the NANO (Neurologic Assessment in Neuro-Oncology) scale.

Results: The mean age of onset of seizure disorder was 19 years (+/- 13 years), whereas the mean duration of epilepsy was 9 years (+/- 12 years). The histopathological examination revealed 2 angiocentric gliomas (ANET), 47 dysembryoplastic neuroepithelial tumors (DNET), 103 gangliogliomas (GG), 23 pilocytic astrocytomas, and 9 pleomorphic xanthoastrocytomas (PXA). In 18 patients, the LEATs were additionally associated with a focal cortical dysplasia (FCD) and these patients were less likely to become seizure-free after resection (p<0.001). A dual pathology in respect of LEAT and hippocampus sclerosis (HS) was found in 26 patients. Immunohistochemistry revealed a CD34-positivity significantly associated with a histological finding of ganglioglioma (p<0.001). The majority of the lesions (n=137, 74%) were located in the temporal lobe and 43 (23%) tumors involved eloquent cortex areas. Gross total resection could have been achieved in 153 (82%) patients. At last available outcome, 135 (73%) patients were seizure free (ILAE 1; Engel Ia). NANO scale evaluation was available in 136 patients. A total of 131 (95%) showed favourable functional outcome (NANO<2). 5 (4%) patients died during the follow-up period because of malignant transformation of the tumor (4 GG and 1 PXA).

Conclusion: Surgery for long-term epilepsy associated tumors provides satisfying epileptological results with favourable functional outcome in most of the cases. Association of LEAT with FCD influenced the epileptological outcome negatively. The malignisation rate is low, but as these tumors occur predominantly in young patients the complete surgical resection remains of a paramount importance for the treatment of LEATs.