IntroductionAlthough vagus nerve stimulation (VNS) is an established therapy for drug-resistant epilepsy, its mechanisms of action remain unresolved, resulting in variable clinical efficacy. Given the strong anatomical and functional coupling between vagal afferents and the locus coeruleus–noradrenergic system, this study investigated whether VNS directly impacts an electrophysiological marker of this system, the P3b event-related potential, and how such modulation relates to therapeutic outcome