The Potential of Invasive and Non-Invasive Vagus Nerve Stimulation to Improve Verbal Memory Performance in Epilepsy Patients
Abstract number :
2.29
Submission category :
11. Behavior/Neuropsychology/Language / 11A. Adult
Year :
2021
Submission ID :
1825686
Source :
www.aesnet.org
Presentation date :
12/1/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:44 AM
Authors :
Ann Mertens, MD - Ghent University Hospital; Stefanie Gadeyne, academic employee – Ghent University Hospital; Emma Lescrauwaet, student – Ghent University Hospital; Evelien Carrette, Professor – Ghent University Hospital; Alfred Meurs, Professor – Ghent University Hospital; Veerle De Herdt, Professor – Ghent University Hospital; Frank Dewaele, Neurosurgeon – Ghent University Hospital; Robrecht Raedt, Professor – Ghent University Hospital; Marijke Miatton, Professor – Ghent University Hospital; Paul Boon, Professor – Ghent University Hospital; Kristl Vonck, Professor – Ghent University Hospital
Rationale: It has previously been demonstrated that acute vagus nerve stimulation (VNS) improves word recognition memory in epilepsy patients. Transcutaneous auricular vagus nerve stimulation (taVNS), a neurostimulation modality that targets the auricular branch of the vagus nerve, has gained interest as a safe and non-invasive alternative to improve cognitive functioning. However, recent studies investigating the effect of taVNS on verbal memory performance in healthy volunteers have shown inconsistent results. In this prospective, randomized, cross-over study, we investigated the effect of both invasive VNS and taVNS on verbal memory performance in drug-resistant epilepsy patients.
Methods: We included 15 drug-resistant epilepsy patients who were recently implanted with a VNS device. During their admission for VNS initiation, all patients conducted a word recognition paradigm in 3 conditions: VNS ON, VNS OFF and taVNS. For each condition, patients were instructed to memorize the highlighted words from 3 text paragraphs. The intervention was delivered during 30 seconds after each paragraph during the consolidation phase of memory formation. Immediate recall scores after each paragraph and delayed recognition scores at the end of the paradigm were obtained for each condition. The word recognition paradigm was repeated after 6 weeks of VNS therapy in 2 conditions: VNS ON and VNS OFF. VNS ON stimulation current was set to 0.5mA in the first session and 1.0mA in the second session. taVNS was delivered with the maximum tolerated stimulation current. We hypothesized to find an intensity-dependent effect of VNS and taVNS on verbal memory performance.
Results: No effect of intervention was seen in both sessions, demonstrating that acute VNS, nor taVNS were able to improve verbal memory performance in this study. Immediate recall and delayed recognition scores were significantly improved in the second session independent of the intervention, suggesting 6 weeks of VNS improved verbal memory performance.
Conclusions: In line with the previous study by this group in healthy volunteers, we could not demonstrate an effect of taVNS on verbal memory performance in epilepsy patients. The positive effects of acute invasive VNS on verbal memory performance could not be replicated. Interestingly, an improved verbal memory performance was seen after 6 weeks of VNS. These findings suggest that longer and more repetitive stimulation of the vagal pathway is required to modulate verbal memory performance.
Funding: Please list any funding that was received in support of this abstract.: Ann Mertens is supported by an “Aspirant” grant of the “Fonds voor Wetenschappelijk Onderzoek” (FWO) Flanders.
Behavior