Glioma Features and Seizure Control During Long-term Follow-up

Background: An epileptic seizure is a common presenting symptom of glioma, or epilepsy may develop later during the disease. Epileptic seizures affect the quality of life in patients with glioma. Good seizure control during 6-12 months follow-up has been associated with gross total resection, radiation therapy and chemotherapy of gliomas. Little is known about seizure control during long-term follow-up and about factors which may affect the prognosis of epilepsy in glioma patients.

Methods: We identified retrospectively all adult patients with diffuse glioma (grade 2-4) associated epilepsy (n = 123) living in Helsinki, who received treatment at Helsinki University Hospital neuro-oncology center during 2013-2015. We excluded patients with histopathological diagnosis prior to 2005. Data was collected from medical records for five years after diagnosis of glioma, or until death.

Results: In this patient cohort 49 (39.8 %) had grade 2 glioma, 19 (15.4 %) had grade 3 glioma and 55 (44.7 %) had grade 4 glioma. 29 (23.6 %) of tumors were astrocytomas, 24 (19.5 %) were oligoastrocytomas, 15 (12.2 %) were oligodendrogliomas and 55 (44.7 %) were glioblastomas. A seizure was the presenting symptom in 87 (70.7 %) of the patients. The majority, 68 (57.6 %) patients were seizure-free for at least 12 months at some point during follow-up and 47 (39.8 %) patients were seizure-free during the last year of follow-up. Survival for five years from glioma diagnosis (p < 0.001), lower grade of tumor (p < 0.001), IDH mutation (p < 0.001), epilepsy as first symptom (p < 0.001), younger age (p < 0.001) and lack of progression (p = 0.021) correlated with seizure freedom at the end of follow-up. When the results were analyzed separately in survivors and deceased patients, only progression correlated negatively with seizure freedom at the end of follow-up in surviving patients (p = 0.008). In 5-year survivors, longer seizure-free periods were achieved by patients without progression of glioma (p = 0.040) vs patients with progression, or without focal aware (p 0.003) or focal impaired awareness seizures (p = 0.002) vs patients with only focal to bilateral tonic-clonic seizures. In deceased patients, progression (p < 0.001) and lower grade of glioma (p = 0.003) correlated positively and focal aware seizures negatively (p = 0.021) with a longer seizure-free period. In all patients, freedom of seizures at the end of follow-up was less likely for patients who had focal aware (p = 0.015) than for patients without focal aware seizures.

Conclusion: There are differences in seizure-free times in patients with grade 2-4 glioma and epilepsy. The results suggest that the prognosis of glioma may be the most important factor influencing the prognosis of epilepsy.