scholarly journals Differential Effects of Afferent and Efferent Vagus Nerve Stimulation on Gastric Motility Assessed with Magnetic Resonance Imaging

2019 ◽  
Author(s):  
Kun-Han Lu ◽  
Jiayue Cao ◽  
Robert Phillips ◽  
Terry L Powley ◽  
Zhongming Liu
Keyword(s):  
Magnetic Resonance Imaging ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Gastric Motility ◽  
Vagus Nerve Stimulation ◽  
Electrical Activation ◽  
Resonance Imaging ◽  
Afferent Pathway ◽  
Efferent Pathway ◽  
Stimulation Of

AbstractBackgroundVagus nerve stimulation (VNS) is an emerging bioelectronic therapy for regulating food intake and controlling gastric motility. However, the functional impact of different VNS parameters on postprandial gastric motility remains incompletely characterized. Moreover, while most studies focused on stimulating the motor limb (i.e. efferent VNS) of the vagovagal circuitry, the contribution of electrically activating the reflex arc of the circuitry (i.e. afferent VNS) to downstream control of gastric function has seldom been investigated.MethodsHere, we used dynamic gastric magnetic resonance imaging (MRI) to assess antropyloric motility in anesthetized rats during which VNS was applied to the left cervical vagus. The configuration of VNS was varied in terms of directionality (i.e. afferent, efferent or combined afferent and efferent VNS) as well as parameter settings (i.e. pulse amplitude, pulse width, and frequency). The motility measurements were computed using a previously developed computer-assisted image processing pipeline.Key ResultsWe found that electrical activation that favored the afferent pathway could promote gastric motility and coordination more effectively than direct activation of the efferent pathway. A reduction in antral contraction amplitude and pyloric tone under high-dose efferent VNS highlighted the inhibitory role of the efferent vagovagal circuitry.Conclusions & InferencesThis study demonstrated the direct and reflex gastric responses to cervical VNS measured with MRI. Our findings suggest that selective stimulation of vagal afferents is potentially more favorable than stimulation of vagal efferents in facilitating coordinated antropyloric motility.Key PointsVagus nerve stimulation is emerging as a new bioelectronic therapy for remedying gastric symptoms. However, the effects of graded VNS settings and directionality preferences of VNS on gastric functions remain incompletely characterized.Dynamic gastric MRI revealed that electrical activation of the afferent pathway could promote antropyloric motility more effectively than direct activation of the efferent pathway.MRI can noninvasively characterize post-prandial gastric motility with high spatial and temporal resolution that could be used to guide the selection of VNS settings.

scholarly journals A systematic review of magnetic resonance imaging in patients with an implanted vagus nerve stimulation system

2021 ◽  
Author(s):  
S. Fetzer ◽  
M. Dibué ◽  
A. M. Nagel ◽  
R. Trollmann
Keyword(s):  
Magnetic Resonance Imaging ◽  
Systematic Review ◽  
Magnetic Resonance ◽  
Adverse Events ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Resonance Imaging ◽  
Mri Scan ◽  
Pubmed Database

Abstract Purpose Vagus nerve stimulation (VNS) is an effective adjunctive treatment for drug-resistant epilepsy (DRE) and difficult-to-treat depression (DTD). More than 125.000 patients have been implanted with VNS Therapy® System (LivaNova PLC) since initial approval. Patients with DRE often require magnetic resonance imaging (MRI) of the brain during the course of their disease. VNS Therapy System devices are labeled to allow MRI under certain conditions; however, there are no published comprehensive articles about the real-world experience using MRI in patients with implanted VNS devices. Methods A systematic review in accordance with PRISMA statement was performed using PubMed database. Full-length articles reporting MRI (1.5 T or 3 T scanner) of patients with implanted VNS for DRE or DTD and published since 2000 were included. The primary endpoint was a positive outcome that was defined as a technically uneventful MRI scan performed in accordance with the VNS Therapy System manufacturer guidelines and completed according to the researchers’ planned scanning protocol without harm to the patient. Results Twenty-six articles were eligible with 25 articles referring to the VNS Therapy System, and 216 patients were included in the analysis. No serious adverse events or serious device-related adverse events were reported. MRI scan was prematurely terminated in one patient due to a panic attack. Conclusion This systematic review indicates that cranial MRI of patients with an implanted VNS Therapy System can be completed satisfactorily and is tolerable and safe using 1.5 T and 3 T MRI scanners when performed in adherence to the VNS manufacturer’s guidelines.

scholarly journals Vagus Nerve Stimulation Promotes Gastric Emptying by Increasing Pyloric Opening Measured with Magnetic Resonance Imaging

2018 ◽  
Author(s):  
Kun-Han Lu ◽  
Jiayue Cao ◽  
Steven Oleson ◽  
Matthew P Ward ◽  
Terry L Powley ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Gastric Emptying ◽  
Magnetic Resonance ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Pyloric Sphincter ◽  
Computer Assisted ◽  
List Type ◽  
Resonance Imaging

AbstractBackgroundVagus nerve stimulation (VNS) is an emerging electroceutical therapy for remedying gastric disorders that are poorly managed by pharmacological treatments and/or dietary changes. Such therapy seems promising since the vagovagal neurocircuitry controlling the enteric nervous system strongly influences gastric functions.MethodsHere, the modulatory effects of left cervical VNS on gastric emptying in rats was quantified using a 1) feeding protocol in which the animal voluntarily consumed a post-fast, gadolinium-labeled meal and 2) newly developed, robust, sensitive and non-invasive imaging strategy to measure antral motility, pyloric activity and gastric emptying based on contrast-enhanced magnetic resonance imaging (MRI) and computer-assisted image processing pipelines.Key ResultsVNS significantly accelerated gastric emptying (control vs. VNS: 24.9±3.5% vs. 40.7±3.9% of meal emptied per 4hrs, p<0.05). This effect resulted from a greater relaxation of the pyloric sphincter (control vs. VNS: 1.4±0.2 vs. 2.5±0.5 mm2cross-sectional area of lumen, p<0.05), without notable changes in antral contraction amplitude (control vs. VNS: 30.6±3.0% vs. 32.5±3.0% occlusion), peristaltic velocity (control vs. VNS: 0.67±0.03 vs. 0.67±0.03 mm/s), or frequency (control vs. VNS: 6.3±0.1 vs. 6.4±0.2 cpm). The degree to which VNS relaxed the pylorus positively correlated with gastric emptying rate (r = 0.5465, p<0.01).Conclusions & InferencesThe MRI protocol employed in this study is expected to enable advanced preclinical studies to understand stomach pathophysiology and its therapeutics. Results from this study suggest an electroceutical treatment approach for gastric emptying disorders using cervical VNS to control the degree of pyloric sphincter relaxation.Key PointsVagus nerve stimulation is emerging as a new electroceutical therapy for treating gastric disorders. However, its underlying mechanism(s) and therapeutic effect(s) remain incompletely understood.Vagus nerve stimulation significantly accelerated gastric emptying by promoting the relaxation of the pyloric sphincter.MRI offers high spatial and temporal resolution to non-invasively characterize gastric motility and physiology in preclinical animal models.

A literature review on the neurophysiological underpinnings and cognitive effects of transcutaneous vagus nerve stimulation: challenges and future directions

2020 ◽  
Vol 123 (5) ◽  
pp. 1739-1755
Author(s):  
Lorenza Colzato ◽  
Christian Beste
Keyword(s):  
Literature Review ◽  
Vagus Nerve ◽  
Brain Stimulation ◽  
Nerve Stimulation ◽  
Vagus Nerve Stimulation ◽  
Cognitive Effects ◽  
Future Directions ◽  
Transcutaneous Vagus Nerve Stimulation ◽  
Stimulation Technique ◽  
Stimulation Of

Brain stimulation approaches are important to gain causal mechanistic insights into the relevance of functional brain regions and/or neurophysiological systems for human cognitive functions. In recent years, transcutaneous vagus nerve stimulation (tVNS) has attracted considerable popularity. It is a noninvasive brain stimulation technique based on the stimulation of the vagus nerve. The stimulation of this nerve activates subcortical nuclei, such as the locus coeruleus and the nucleus of the solitary tract, and from there, the activation propagates to the cortex. Since tVNS is a novel stimulation technique, this literature review outlines a brief historical background of tVNS, before detailing underlying neurophysiological mechanisms of action, stimulation parameters, cognitive effects of tVNS on healthy humans, and, lastly, current challenges and future directions of tVNS research in cognitive functions. Although more research is needed, we conclude that tVNS, by increasing norepineprine (NE) and gamma-aminobutyric acid (GABA) levels, affects NE- and GABA-related cognitive performance. The review provides detailed background information how to use tVNS as a neuromodulatory tool in cognitive neuroscience and outlines important future leads of research on tVNS.

scholarly journals Alternative Paradigm of Selective Vagus Nerve Stimulation Tested on an Isolated Porcine Vagus Nerve

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Polona Pečlin ◽  
Janez Rozman
Keyword(s):  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Fibre Type ◽  
Vagus Nerve Stimulation ◽  
Experimental Testing ◽  
Present Stage ◽  
Stage Of Development ◽  
Isolated Segment ◽  
Left Vagus ◽  
Stimulation Of

Alternative paradigm for spatial and fibre-type selective vagus nerve stimulation (VNS) was developed using realistic structural topography and tested in an isolated segment of a porcine cervical left vagus nerve (LVN). A spiral cuff (cuff) containing a matrix of ninety-nine electrodes was developed for selective VNS. A quasitrapezoidal stimulating pulse (stimulus) was applied to the LVN via an appointed group of three electrodes (triplet). The triplet and stimulus were configured to predominantly stimulate the B-fibres, minimizing stimulation of the A-fibres and by-passing the stimulation of the C-fibres. To assess which fibres made the most probable contribution to the neural response (NR) during selective VNS, the distribution of conduction velocity (CV) within the LVN was considered. Experimental testing of the paradigm showed the existence of certain parameters and waveforms of the stimulus, for which the contribution of the A-fibres to the NR was slightly reduced and that of the B-fibres was slightly enlarged. The cuff provided satisfactory fascicle discrimination in selective VNS as well as satisfactory fascicle discrimination during NR recording. However, in the present stage of development, fibre-type VNS remained rather limited.

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