Vagus nerve stimulation modulating the directed brain network of patients with drug-resistant epilepsy

Vagus nerve stimulation (VNS) has been suggested to be an effective method for regulating seizures in patients with drug-resistant epilepsy. This study aims to investigate the effects of VNS on the directed brain networks of patients with drug-resistant epilepsy, offering new insights into the clinical treatment of epilepsy using VNS. We analyzed EEG data from drug-resistant epilepsy patients who underwent VNS treatment between 2017 and 2021. We used the directed phase transfer entropy (dPTE) to evaluate effective connectivity in various frequency bands (delta, theta, alpha, beta, gamma) among scalp EEG channels. We computed mean dPTE values for each node to assess changes in information flow, in-degree, and out-degree as indicators of node properties. Statistical analyses have been performed to compare conditions before and after VNS treatment. The results showed that before VNS treatment, the primary information flow was from the anterior to the posterior regions. However, after VNS treatment, this flow shifted to a posterior-to-anterior direction. Significant changes in directed network nodes and edges were found to be frequency-dependent, with the most prominent changes occurring in the frontal and parietal-occipital regions. In-degree, out-degree, and directed edges also exhibited remarkable changes after VNS treatment. Notably, weakened edges were mainly observed in the frontal lobe, while enhanced edges were predominantly from the parietal-occipital region to the frontal lobe. In summary, VNS treatment alters the brain network in patients with drug-resistant epilepsy, promoting forward information flow, and contributing to our better understanding of VNS as an epilepsy treatment.