Early EEG hyperexcitability is associated with decreased survival in newly diagnosed IDH-wildtype glioma.

PURPOSE: The relationship between peritumoral neuronal activity, early onset clinical seizures, and glioma survival outcomes remains poorly understood. Hyperexcitability on continuous EEG in the peri-operative period was studied as a prognostic biomarker in patients with newly diagnosed IDH-wildtype diffuse glioma.
METHODS: A retrospective observational cohort study was performed including adults with newly diagnosed diffuse glioma, absence of IDH1/2 mutations, and continuous EEG monitoring prior to chemoradiation and within 1 month of initial resection. EEG hyperexcitability was defined by the presence of lateralized periodic discharges and/or electrographic seizures. The primary outcome of overall survival was estimated using the Kaplan-Meier method and compared between groups using multivariate Cox proportional hazards model.
RESULTS: There were 424 patients without continuous EEG and 32 with continuous EEG, of whom lateralized periodic discharges and/or electrographic seizures were seen in 17 (53%). Peri-operative EEG hyperexcitability was associated with decreased overall survival in multivariate analysis (median 12.5 [95% CI 6.2-25.6] months with hyperexcitability versus median 19.9 [95% CI 8.9-53.5] months without hyperexcitability, p = 0.043). Compared to patients without continuous EEG, overall survival was decreased in patients with hyperexcitability (p < 0.0001) and similar in patients without hyperexcitability (p = 0.193). Patients with and without hyperexcitability had similar rates of exposure to anti-seizure medication at baseline, and in long-term follow-up had no difference in number of medications required for seizure control.
CONCLUSIONS: These findings indicate the potential prognostic value of a clinical EEG biomarker of glioma aggressiveness prior to the initiation of chemoradiation.