Linking New Onset Epilepsy Risk-of-Relapse to EEG Connectivity and Microstates

PURPOSE: Antiseizure medication is the first-line treatment for new-onset-epilepsy, leading to seizure control in 70% to 80% of patients. An early identification of an appropriate treatment is extremely important to avoid seizure relapses, and biomarkers for relapse risk are needed to avoid any delays. The authors investigated electroencephalography (EEG)-based brain connectivity and microstates between patients with new-onset epilepsy who responded to treatment (SZ-FREE) and patients who relapsed (SZ-REL), to link potential differences to treatment response. METHODS: Sixty-two patients with new-onset epilepsy for whom an EEG was performed before treatment initiation, after a first seizure event. The authors computed EEG connectivity for delta, theta, alpha, beta, and gamma frequencies, and microstates. By performing mixed-model analyses, the authors tested connectivity differences across frequency bands and microstate characteristic changes between SZ-FREE and SZ-REL. RESULTS: After treatment, 51 patients remained seizure free while 11 relapsed within 6 months. The authors observed a significant interaction between frequency bands and groups (P < 0.001). Post hoc tests showed delta (P = 0.006) and theta (P = 0.012) decreases, and alpha increases (P < 0.001) for patients with SZ-REL compared with patients with SZ-FREE. Microstate C had a significantly higher global explained variance for patients with SZ-REL than patients with SZ-FREE (P = 0.021), while microstates A occurred more frequently in SZ-REL (P = 0.031). CONCLUSIONS: EEG connectivity and microstates in the first EEG within 24 hours after the initial seizure hold valuable information related to the drug responsiveness in patients with new-onset epilepsy. SIGNIFICANCE: EEG connectivity and microstates are potential markers of treatment response.