Optimization of Vagus Nerve Therapy : a study of the behavioral and electrophysiological effects of transcutaneous VNS
(2019) 3rd International Brain Stimulation Conference — Location: Vancouver (24.February.2019)
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- Abstract
- With only 1/3 of refractory epileptic patients responding to vagus nerve stimulation (VNS) therapy, this intervention still needs further research. Transcutaneous-VNS (T-VNS) is a non-invasive device stimulating the auricular branch of the vagus nerve, which was suggested to affect pain perception. Thus, T-VNS effects on behavioral and brain responses to nociceptive and non-nociceptive somatosensory stimuli could account for potential biomarkers of VNS effectiveness. 5 healthy volunteers participated to the study. During a 2-day protocol, T-VNS was delivered on the left ear for 3 hours with randomized active stimulation (cymbae conchae) or active control (earlobe). Before and after T-VNS, nociceptive (CO2 laser recruiting either A-δ or C fibers; 128 mN pinprick) and non-nociceptive (vibrotactile; cool) stimuli were applied on the contralateral hand dorsum. Perception thresholds, intensity, and quality were retrieved as behavioral responses. Using scalp electroencephalography (EEG; sampling rate: 512 Hz), we recorded event-related potentials (ERPs) elicited by thermonociceptive, cool, and vibrotactile stimuli, delivered in separate blocks (40 stimuli per block), randomized across participants. Both active T-VNS and sham stimulation showed antinociceptive effects, reflected in a decrease of the amplitude of the ERPs elicited by thermonociceptive stimuli in 4 et 3 participants respectively. In contrast, no clear effect was found for behavioral responses, indicating a dissociation between ERPs and perception. These preliminary results suggest that the overall antinociceptive effect of t-VNS is rather unspecific, most probably resulting from the global stimulation of the auricular nerves rather than that of the sole vagal branch. Additional comparison with trigeminal stimulation and more participants are needed to increase statistical power and significance.
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Dumoulin, M., Liberati, G., Mouraux, A., & El Tahry, R. (2019). Optimization of Vagus Nerve Therapy : a study of the behavioral and electrophysiological effects of transcutaneous VNS. Brain Stimulation : basic, translational and clinical research in neuroscience, 12(2), 454. https://doi.org/10.1016/j.brs.2018.12.473 (Original work published 2019)