Epilepsy Surgery after High-grade Brain Tumors - Two Case Presentations and Review of the Literature

Background: In the case of high-grade brain tumours (WHO grade III-IV), chemotherapy and/or radiation therapy is usually performed in addition to resection of the tumor. Chronic refractory epilepsy can occur due to remaining tumor cells or radiation-related secondary brain damage. Invasive EEG monitoring with subdural or stereotactically implanted depth electrodes are often required to test the indication for epilepsy surgery. The re-craniotomy and the channels of the depth electrodes carry the potential risk of residual tumor cell displacement.

Question: There is little scientific data on the safety of invasive EEG video monitoring and the success of epilepsy surgery after high-grade brain tumors. We present two cases and a review of the literature.

Material and Methods: In patient 1, 4 years after resection of an anaplastic ependymoma (WHO grade III) followed by chemotherapy and radiotherapy, a refractory epilepsy occurred. Invasive EEG monitoring with depth electrodes and resection of the epileptogenic lesions were performed. Patient 2 developed epilepsy 7 years after removal and radiochemotherapy.of a plexus carcinoma (WHO grade III). After invasive monitoring, epilepsy surgery was performed.

Results: Both patients are postoperatively free of seizures (Engel Class Ia). In patient 1 the antiepileptic medication was discontinued, patient 2 is further treated with lacosamide. The current literature on epilepsy surgery after high-grade brain tumors is being discussed.

Discussion: Our cases show that invasive EEG monitoring and resection of the epileptogenic focus can be successfully performed in epilepsies following high-grade brain tumors. In order to assess the risks of invasive monitoring and surgery after malignant brain tumors and the probability of postoperative freedom from seizures, studies of larger patient populations are required.

No conflict of interest has been declared by the author(s).