• Citer

Longitudinal follow-up of vagus nerve stimulation-induced LMEPs dose-response curve for VNS parameters optimization

par Germany Morrison, Enrique ;Danthine, Venethia;Torres Sánchez, Andrés;Delbeke, Jean;Nonclercq, Antoine ;El Tahry, Riëm
Référence (23-26 February, 2025: Kobe, Japan), 6th International Brain Stimulation Conference Abstract
Publication Publié, 2025-02

Abstract de conférence

• Accès en ligne
• Détails
• Contenu
• Statistiques

Résumé :

Vagus Nerve Stimulation (VNS) is an established therapy for drug-resistant epilepsy but lacks a reliable biomarker to optimize its efficacy. Laryngeal Motor Evoked Potentials (LMEPs), markers of efferent A-fiber activation, can be non-invasively recorded via surface electrodes on the laryngeal prominence. A previous study (Berger 2023) showed a relationship between VNS parameters and LMEP saturation value. However, little is known about how the vagus nerve recovers post-surgery and how LMEPs change during this period. This study aims to longitudinally assess efferent and afferent markers of VNS action over time. Twelve adult patients with drug-resistant epilepsy scheduled for VNS implantation were prospectively recruited. LMEP recordings were obtained at four post-surgery time points: two weeks, one month, three months, and six months. During each session, VNS parameters were set to deliver a 7-second "ON" period in single trigger manual magnet mode, with 250 uS pulse width, 30 Hz pulse frequency, and increasing current intensities in steps of 0.125 mA, up to the routine (clinical) stimulation intensity plus 0.25 mA. This allowed for the construction of dose-response curves at each time point. Results showed that the intensity threshold required to induce LMEPs decreased over time, stabilizing at a lower value by six months post-implantation in six out of twelve patients. Initially, higher thresholds at two weeks post-surgery progressively declined at subsequent time points, suggesting increasing excitability of the vagus nerve as it recovers from surgical implantation. The decreasing LMEP induction threshold over time indicates that LMEPs depend on both stimulation intensity and nerve recovery. LMEPs may serve as a reliable biomarker reflecting vagus nerve function and the efficacy of VNS therapy over time. Incorporating LMEP monitoring into clinical practice could enhance the optimization of VNS parameters, potentially improving therapeutic outcomes for patients with drug-resistant epilepsy.