title: Preliminary findings of cerebral responses on transcutaneous vagal nerve stimulation on experimental heat pain.
abstract: Transcutaneous vagal nerve stimulation (TVNS) is a promising complementary method of pain relief. However, the neural networks associated with its analgesic effects are still to be elucidated. Therefore, we conducted two functional magnetic resonance imaging (fMRI) sessions, in a randomized order, with twenty healthy subjects who were exposed to experimental heat pain stimulation applied to the right forearm using a Contact Heat-Evoked Potential Stimulator. While in one session TVNS was administered bilaterally to the concha auriculae with maximal, non-painful intensity, the stimulation device was switched off in the other session (placebo condition). Pain thresholds were measured before and after each session. Heat stimulation elicited fMRI activation in cerebral pain processing regions. Activation magnitude in the secondary somatosensory cortex, posterior insula, anterior cingulate and caudate nucleus was associated with heat stimulation without TVNS. During TVNS, this association was only seen for the right anterior insula. TVNS decreased fMRI signals in the anterior cingulate cortex in comparison with the placebo condition; however, there was no relevant pain reducing effect over the group as a whole. In contrast, TVNS compared to the placebo condition showed an increased activation in the primary motor cortex, contralateral to the site of heat stimulation, and in the right amygdala. In conclusion, in the protocol used here, TVNS specifically modulated the cerebral response to heat pain, without having a direct effect on pain thresholds.
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Medicine, University Medicine Greifswald, Sauerbruchstrasse, 17475, Greifswald, Germany. taras@uni-greifswald.de.
authors.forename: Taras
authors.initials: T
authors.lastname: Usichenko
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Medicine, University Medicine Greifswald, Sauerbruchstrasse, 17475, Greifswald, Germany.|Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Freiburgstrasse 10, Bern, Switzerland.|Institute for Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Sauerbruchstrasse, Greifswald, 17475, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Laqua
authors.affiliation: Department of Anesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Medicine, University Medicine Greifswald, Sauerbruchstrasse, 17475, Greifswald, Germany.
authors.forename: Bianca
authors.initials: B
authors.lastname: Leutzow
authors.affiliation: Institute for Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Sauerbruchstrasse, Greifswald, 17475, Germany.
authors.forename: Martin
authors.identifier: 0000-0003-4519-4956
authors.initials: M
authors.lastname: Lotze
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001931:Brain Mapping; D018592:Cross-Over Studies; D005260:Female; D005542:Forearm / Q000503:physiopathology; D006358:Hot Temperature; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000503:physiopathology; D010146:Pain / Q000000981:diagnostic imaging / Q000503:physiopathology*; D059408:Pain Management; D017288:Pain Threshold / Q000502:physiology; D004561:Transcutaneous Electric Nerve Stimulation; D055536:Vagus Nerve Stimulation; D055815:Young Adult
keywords: Functional MRI; Placebo stimulation; Thermal pain; Transcutaneous vagal nerve stimulation (TVNS)