Fast cycle of vagus nerve stimulation is associated with increased sleep‐related breathing disorder in patients with epilepsy

OBJECTIVE: This work was undertaken to study the association between vagus nerve stimulation (VNS) parameters and the apnea-hypopnea index (AHI) measured by polysomnography in patients with drug-resistant epilepsy. METHODS: Patients with epilepsy who underwent polysomnography with an active VNS device between 2018 and 2023 were retrospectively included. VNS output current and cycle speed, defined as the interval between two stimulation-ON (Stim-ON) periods, were correlated with AHI. Demographic, clinical, and polysomnography characteristics were compared between patients with low (≤1.5 mA) or high (>1.5 mA) output current, and between patients with slow VNS cycle (interval between two Stim-ON of >108 s) and fast cycle (interval between two Stim-ON of ≤108 s). Multiadjusted linear regression analysis was performed. RESULTS: Twenty-two patients were included. Output current significantly correlated with AHI, but no difference was found between patients with low versus high output current. Patients with a fast VNS cycle had a significantly higher AHI than patients with a slow VNS cycle. After adjustment for age, number of antiseizure medications, body mass index, and gender, only the cycle speed remained significant, with no significant association with output current. SIGNIFICANCE: Cycle speed, defined as a short interval between two stimulations, is associated with increased sleep-related respiratory events in patients with epilepsy treated with VNS. Increasing the duration between two stimulations may help clinicians to reduce VNS-induced sleep-related breathing disorder.