Branch Of Vagus Nerve Research Articles

The role of the cardiac vagus in maintaining cardiac function during exercise

There is a strong association between parasympathetic nervous system activity (vagal tone) and physical fitness. High vagal tone is associated with increased capacity to exercise and overall cardiovascular health. Evidence for vagal withdrawal during exercise comes from historic studies examining heart rate control and the use of cholinergic blockers. However, more recent studies have challenged this assumption. We hypothesized that cardiac vagal activity increases during exercise and maintains cardiac function via neurotransmitters other than acetylcholine. The left cardiac vagal branch was identified in anesthetized open-chested sheep. Cardiac innervation of the left cardiac vagal branch was confirmed with lipophilic tracer dyes (DiO). Custom-built coil electrodes were placed around the left cardiac vagal branch. 3-10 days after surgery, conscious, direct recordings of cardiac vagal nerve activity (CVNA), cardiac output, coronary artery blood flow and heart rate were recorded in adult female sheep during whole-body treadmill exercise. Sheep were exercised with pharmacological blockers of acetylcholine (atropine, 250 mg), vasoactive intestinal peptide (VIP) ([4Cl−D-Phe6,Leu17]-VIP 25 μg), or saline control, randomized on different days. In a subset of sheep, the left cardiac vagal branch was denervated. Neural innervation from the cardiac vagal branch is seen at major cardiac ganglionic plexi, and within the fat pads associated with the coronary arteries. Directly recorded CVNA increased during exercise. CVNA increases during the lowest exercise intensity and plateaus as exercise intensity increases. Left cardiac vagal branch, denervation attenuated the maximum changes in coronary artery blood flow (maximum exercise, control: 63.5 ± 5.9 ml/min, n = 8, cardiac vagal denervated: 32.7 ± 5.6 ml/min, n = 6, mean ± SEM. P = 2.5x10−7. Two-way ANOVA-interaction), cardiac output and heart rate during exercise. Atropine did not affect any cardiac parameters during exercise, but VIP antagonism significantly reduced coronary artery blood flow during exercise to a similar level to vagal denervation (maximum exercise, paired: control: 68.2 ± 6.0 ml/min, VIP antagonism: 44.9 ± 3.9 ml/min, n = 6, mean ± SEM. P = 4.8x10−3. Two-way ANOVA-interaction). Our study challenges the conventional view and demonstrates that cardiac vagal nerve activity increases and is crucial for maintaining cardiac function during exercise. Furthermore, our findings show that the dynamic modulation of coronary artery blood flow during exercise is mediated by VIP and that acetylcholine has no role in modulating cardiac function during exercise. This work is supported by the Health Research Council of New Zealand 23/119 (Fellowship. JS) and the New Zealand Heart Foundation (JS, RR). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Identification of vagal afferent nerve endings in the mouse colon and their spatial relationship with enterochromaffin cells

Understanding how the gut communicates with the brain, via sensory nerves, is of significant interest to medical science. Enteroendocrine cells (EEC) that line the mucosa of the gastrointestinal tract release neurochemicals, including the largest quantity of 5-hydroxytryptamine (5-HT). How the release of substances, like 5-HT, from enterochromaffin (EC) cells activates vagal afferent nerve endings is unresolved. We performed anterograde labelling from nodose ganglia in vivo and identified vagal afferent axons and nerve endings in the mucosa of whole-mount full-length preparations of mouse colon. We then determined the spatial relationship between mucosal-projecting vagal afferent nerve endings and EC cells in situ using 3D imaging. The mean distances between vagal afferent nerve endings in the mucosa, or nearest varicosities along vagal afferent axon branches, and the nearest EC cell were 29.6 ± 19.2 μm (n = 107, N = 6) and 25.7 ± 15.2 μm (n = 119, N = 6), respectively. No vagal afferent endings made close contacts with EC cells. The distances between EC cells and vagal afferent endings are many hundreds of times greater than known distances between pre- and post-synaptic membranes (typically 10–20 nm) that underlie synaptic transmission in vertebrates. The absence of any close physical contacts between 5-HT-containing EC cells and vagal afferent nerve endings in the mucosa leads to the inescapable conclusion that the mechanism by which 5-HT release from ECs in the colonic mucosa occurs in a paracrine fashion, to activate vagal afferents.

Effect of Preserving the Pulmonary Branch of Vagus Nerve on Postoperative Cough in Patients with Stage I Peripheral Lung Adenocarcinoma

Cough is one of the main complications after pulmonary surgery, which seriously affects the postoperative quality of life. Preserving the pulmonary branch of vagus nerve may reduce the incidence of postoperative cough. Therefore, the aim of this study was to investigate whether preserving the pulmonary branch of the vagus nerve could reduce the incidence of postoperative chronic cough in patients with stage I peripheral lung adenocarcinoma. A total of 125 patients who underwent single-port thoracoscopic radical resection for lung cancer in the Department of Thoracic Surgery, The First Affiliated Hospital of University of Science and Technology of China from June 2022 to June 2023 were retrospectively selected, and divided into two groups according to whether the vagopulmonary branch was preserved during the operation, namely, the vagopulmonary branch group (n=61) and the traditional group (n=64). The general clinical data, perioperative conditions, lymph node dissection, Mandarin Chinese version of The Leicester Cough Questionnaire (LCQ-MC) scores before and 8 weeks after operation were recorded in the two groups. Both the two groups were divided into tamponade group and non-tamponade group according to whether autologous fat or gelatin sponge was tamponade after lymph node dissection. LCQ-MC scores and postoperative chronic cough of both groups were calculated. The LCQ-MC score of the traditional group was significantly lower than that of the vagopulmonary branch group in physiological, psychological, social and total scores at 8 weeks after surgery, and the difference was statistically significant (P<0.05). There were more cough patients in the traditional group than the vagopulmonary branch group at 8 weeks after surgery, with significant difference (P=0.006). Subgroup analysis was conducted separately for the vagopulmonary branch group and the traditional group. Among the patients in the vagopulmonary branch group and the traditional group, the LCQ-MC scores of the non-tamponade group 8 weeks after surgery were lower than those of the tamponade group (P<0.05). There were more patients with cough in the group 8 weeks after surgery than in the tamponade group (P=0.001, P=0.024). For patients with stage I peripheral lung adenocarcinoma, the preservation of the pulmonary branch of vagus nerve is safe and effective, which can reduce the incidence of postoperative chronic cough and improve the postoperative quality of life of the patients.

Subdiaphragmatic vagal nerve stimulation attenuates the development of hypertension and alters nucleus of the solitary tract transcriptional networks in the spontaneously hypertensive rat.

Augmented vagal signaling may be therapeutic in hypertension. Most studies to date have used stimulation of the cervical vagal branches. Here, we investigated the effects of chronic intermittent electric stimulation of the ventral subdiaphragmatic vagal nerve branch (sdVNS) on long-term blood pressure, immune markers, and gut microbiota in the spontaneously hypertensive rat (SHR), a rodent model of hypertension characterized by vagal dysfunction, gut dysbiosis, and low-grade inflammation. We evaluated the effects of sdVNS on transcriptional networks in the nucleus of the solitary tract (NTS), a major cardioregulatory brain region with direct gut vagal projections. Male juvenile SHRs were implanted with radiotelemetry transmitters and vagal nerve cuffs for chronic intermittent electric sdVNS, applied three times per day for 7 consecutive weeks followed by 1 wk of no stimulation. Blood pressure was measured once a week using telemetry in the sdVNS group as well as age-matched sham-stimulated SHR controls. At the endpoint, colonic and circulating inflammatory markers, corticosterone, and circulating catecholamines were investigated. Bacterial 16 s sequencing measured gut bacterial abundance and composition. RNA sequencing evaluated the effects of sdVNS on transcriptional networks in the NTS. SHRs that received sdVNS exhibited attenuated development of hypertension compared with sham animals. No changes in peripheral inflammatory markers, corticosterone, or catecholamines and no major differences in gut bacterial diversity and composition were observed following sdVNS, apart from decreased abundance of Defluviitaleaceale bacterium detected in sdVNS SHRs compared with sham animals. RNA sequencing revealed significant sdVNS-dependent modulation of select NTS transcriptional networks, including catecholaminergic and corticosteroid networks.NEW & NOTEWORTHY We show that stimulation of the ventral subdiaphragmatic vagal nerve branch may be a promising potential approach to treating hypertension. The data are especially encouraging given that rodents received only 30 min per day of intermittent stimulation therapy and in view of the potential of long-term blood pressure effects that are not stimulus-locked.

Cardiac Vagal Nerve Activity Increases During Exercise to Enhance Coronary Blood Flow.

The phrase complete vagal withdrawal is often used when discussing autonomic control of the heart during exercise. However, more recent studies have challenged this assumption. We hypothesized that cardiac vagal activity increases during exercise and maintains cardiac function via transmitters other than acetylcholine. Chronic direct recordings of cardiac vagal nerve activity, cardiac output, coronary artery blood flow, and heart rate were recorded in conscious adult sheep during whole-body treadmill exercise. Cardiac innervation of the left cardiac vagal branch was confirmed with lipophilic tracer dyes (DiO). Sheep were exercised with pharmacological blockers of acetylcholine (atropine, 250 mg), VIP (vasoactive intestinal peptide; [4Cl-D-Phe6,Leu17]VIP 25 µg), or saline control, randomized on different days. In a subset of sheep, the left cardiac vagal branch was denervated. Neural innervation from the cardiac vagal branch is seen at major cardiac ganglionic plexi, and within the fat pads associated with the coronary arteries. Directly recorded cardiac vagal nerve activity increased during exercise. Left cardiac vagal branch denervation attenuated the maximum changes in coronary artery blood flow (maximum exercise, control: 63.5±5.9 mL/min, n=8; cardiac vagal denervated: 32.7±5.6 mL/min, n=6, P=2.5×10-7), cardiac output, and heart rate during exercise. Atropine did not affect any cardiac parameters during exercise, but VIP antagonism significantly reduced coronary artery blood flow during exercise to a similar level to vagal denervation. Our study demonstrates that cardiac vagal nerve activity actually increases and is crucial for maintaining cardiac function during exercise. Furthermore, our findings show the dynamic modulation of coronary artery blood flow during exercise is mediated by VIP.

Adverse childhood experiences are associated with altered cardiovascular reactivity to head-up tilt in young adults.

Adverse childhood experiences (ACEs) are associated with greater prevalence of cardiovascular disease and altered acute stress reactivity. The current study investigated the effect of ACEs on hemodynamic and autonomic responses to orthostatic stress imposed by 60° head-up tilt (HUT) in young adults. Two-hundred twenty-six healthy young adults (age = 22.6 ± 1.5 yr; n = 116 females) without cardiovascular disease participated and had complete data. Participants underwent supine blood pressure (BP), R-R interval (RRI), cardiac output (CO), total peripheral resistance (TPR), and cardiovagal baroreflex sensitivity (cvBRS) testing followed by a transition to 60° HUT where measures were reassessed. Childhood adversity exposures were assessed based on categorical exposure and nonexposure to childhood household dysfunction and maltreatment, and <4 and ≥4 types of ACEs. Significantly greater increases in SBP (P < 0.05), DBP, MAP, and TPR (P < 0.01; all) following 60° HUT were observed in individuals with ≥4 compared with those with <4 types of ACEs. Attenuated decreases in RRI and cvBRS were observed in those with ≥4 types of ACEs (P < 0.05). Experiencing ≥4 types of ACEs was associated with augmented BP and TPR reactivity and a blunted decrease in cvBRS in response to 60° HUT in young adults. Results suggest that a reduced vagal response to orthostatic stress is present in those who have experienced ≥4 types of ACEs that may promote autonomic dysfunction. Future research examining the sympathetic and vagal baroreflex branches is warranted.

Pulmonary vein isolation-induced vagal nerve injury and gastric motility disorders detected by electrogastrography: The side effects of pulmonary vein isolation in atrial fibrillation (SEPIA) study.

Safety of pulmonary vein isolation (PVI) has been established in clinical studies. However, despite prevention efforts the incidence of damage to (peri)-esophageal tissue has not decreased, and the pathophysiology is incompletely understood. Damage to vagal nerve branches may be involved in lesion progression to atrio-esophageal fistula. Using electrogastrography, we assessed the incidence of periesophageal vagal nerve injury (VNI) following atrial fibrillation ablation and its association with procedural parameters and endoscopic results. Patients were studied using electrogastrography, endoscopy, and endoscopic ultrasound before and after cryoballoon (CB) or radiofrequency (RF) PVI. The incidence of ablation-induced neuropathic pattern (indicating VNI) in pre- and postprocedural electrogastrography was assessed and correlated with endoscopic results and ablation data. Between February 2021 und January 2022, 85 patients (67 ± 10 years, 53% male) were included, 33 were treated with CB and 52 with RF (38 with moderate power moderate duration [25-30 W] and 14 with high power short duration [50 W]). Ablation-induced VNI was detected in 27/85 patients independent of the energy form. Patients with VNI more frequently had postprocedural endoscopically detected pathology (8% mucosal esophageal lesions, 36% periesophageal edema, 33% food retention) but there was incomplete overlap. Pre-existing esophagitis increased the likelihood of VNI. Ablation data and esophageal temperature data did not predict VNI. PVI-induced VNI is quite common and independent of ablation energy source. VNI is part of (peri)-esophageal damage and only partially overlaps with endoscopic findings. VNI-associated acidic reflux may be involved in the complex pathophysiology of esophageal lesion progression to fistula.

Use of a bio-electronic device comprising of targeted dual neuromodulation of the hepatic and celiac vagal branches demonstrated enhanced glycemic control in a type 2 diabetic rat model as well as in an Alloxan treated swine model.

There is an unmet need for new type 2 diabetes treatments providing improved efficacy, durability and customized to improve patient's compliance. Bio-electronic neuromodulation of Vagus nerve branches innervating organs that regulate plasma glucose, may be a method for treating type 2 diabetes. The pancreas has been shown to release insulin during Vagus stimulation. The hepatic vagal branch, innervating the liver, has been shown to decrease glucose release and decrease insulin resistance following ligation. However, standalone stimulation of the Vagus nerve has shown mixed results and Vagus nerve ligation has undesirable effects. Little is known; however, of the effect on plasma glucose with combined neuromodulation consisting of stimulation of the celiac branch innervating the pancreas with simultaneous high frequency alternating current (HFAC) blockade of the hepatic branch. This study tested the effects of this approach on increasing glycemic control in rat a model of type 2 diabetes and Alloxan treated swine. Zucker obese (fatty) male rats (ZDF fa/fa) were used as a model of type 2 diabetes as well as glucose intolerant Alloxan treated swine. In ZDF rat experiments glycemic control was accessed with an intravenous glucose tolerance test during HFAC-induced hepatic branch block with concurrent celiac stimulation (HFAC + stimulation). In swine experiments glycemic control was accessed by an oral glucose tolerance test during HFAC + stimulation. Insulin measurements were taken prior to and following swine experiments giving insight into beta cell exhaustion. Histopathology was conducted to determine safety of HFAC + stimulation on Vagal branches. Zucker rats demonstrated a significant improvement to an intravenous glucose tolerance test during HFAC + stimulation compared to sham. There was no significant difference from sham compared to hepatic vagotomy or celiac stimulation. In Alloxan treated swine, when subjected to HFAC + stimulation, there was a significant improvement in glycemic control as measured by an improvement on oral glucose tolerance tests and a decrease in fasting plasma glucose. Insulin responses were similar prior to and following HFAC + stimulation experiments. Histopathology demonstrated healthy swine Vagus nerves. Electrical blockade of the hepatic Vagus branch with simultaneous stimulation of the celiac Vagus branch may be a novel, adjustable and localized approach for a treatment of type 2 diabetes.

Mapping the functional anatomy and topography of the cardiac autonomic innervation for selective cardiac neuromodulation using MicroCT.

Background: Vagus nerve stimulation (VNS) has gained great importance as a promising therapy for a myriad of diseases. Of particular interest is the therapy of cardiovascular diseases, such as heart failure or atrial fibrillation using selective cardiac VNS. However, there is still a lack of organ-specific anatomical knowledge about the fascicular anatomy and topography of the cardiac branch (CB), which diminishes the therapeutic possibilities for selective cardiac neuromodulation. Here, we established a topographical and anatomical map of the superior cardiac VN in two animal species to dissect cervical and cardiac VN morphology. Methods: Autonomic nerves including superior CBs were harvested from domestic pigs and New Zeeland rabbits followed by imaging with microcomputed tomography (µCT) and 3D rendering. The data were analyzed in terms of relevant topographical and anatomical parameters. Results: Our data showed that cardiac vagal fascicles remained separated from other VN fascicles up to 22.19 mm (IQR 14.02–41.30 mm) in pigs and 7.68 mm (IQR 4.06–12.77 mm) in rabbits from the CB point and then started merging with other fascicles. Exchanges of nerve fascicles between sympathetic trunk (ST) and VN were observed in 3 out of 11 nerves, which might cause additional unwanted effects in unselective VNS. Our 3D rendered digital model of the cardiac fascicles was generated showing that CB first remained on the medial side where it branched off the VN, as also shown in the µCT data of 11 pig nerves, and then migrated towards the ventromedial site the further it was traced cranially. Conclusion: Our data provided an anatomical map of the cardiac vagal branches including cervical VN and ST for future approaches of selective cardiac neurostimulation, indicating the best position of selective cardiac VNS just above the CB point.

Modified McKeown vs. traditional McKeown minimally invasive esophagectomy in improving short-term efficacy and the quality of life of esophageal cancers: a retrospective comparative cohort study.

BackgroundTraditional McKeown minimally invasive esophagectomy (MIE-McKeown) with resection of the thoracic and abdominal branches of vagus nerve, the azygos vein and the bronchial artery, is notorious for high complications incidence and sharply decreased quality of life (QoL) postoperatively in esophageal cancer (EC). Recently, reports of preservation of azygos vein arch or the vagus nerve have shown the advantages of decreasing postoperative complication incidence. However, the modified MIE-McKeown with preservation of azygos vein arch, vagus nerve and the bronchial artery has never been investigated in EC. In the present study, we aimed to compare the short-term efficacy and postoperative QoL between modified MIE-McKeown and traditional MIE-McKeown.MethodsA total of 218 eligible patients with esophageal squamous cell carcinoma (ESCC) who met our inclusion criteria between October 2018 and January 2022 in our center were retrospectively enrolled and divided into modified MIE-McKeown group (N=48) and the control group with traditional MIE-McKeown (N=170) according to their surgical procedure. We compared the perioperative parameters (e.g., operation time and postoperative complications) between the two groups. The core quality of life questionnaire (QLQ-C30) (version 3.0) and the EC-specific QoL assessment form (QLQ-OES18) were used to evaluate the QoL in the 2 groups at 1 and 3 months after operation.ResultsThere were no significant differences in baseline characteristics between modified MIE-McKeown group and the control group. Compared with the control group, the modified MIE-McKeown group had significantly lower postoperative drainage volume (551.46±249.45 vs. 812.96±405.82; P<0.001) and a lower incidence of thoracic stomach syndrome (TSS; P=0.001). The bleeding loss in the modified MIE-McKeown group was lower than that in the control group (56.88±20.44 vs. 83.18±97.93; P=0.066), but not significantly. There were no significant differences observed in postoperative complications and other perioperative parameters between the two groups. The results of QLQ-C30 and QLQ-OES18 questionnaire revealed that the modified MIE-McKeown group was associated with better physical function, better global health status and milder symptoms of gastroesophageal reflux and cough.ConclusionsThe modified MIE-McKeown is a safe and efficient procedure and has the potential to improve postoperative health status of patients with EC.

Central and Systemic Effects of Subdiaphragmatic Vagus Nerve Stimulation during the Development of Hypertension in the SHR

IntroductionThe vagus nerve facilitates bidirectional communication between the gut and brain. A low vagal tone has been described in many conditions characterized by inflammation and gut dysbiosis, including hypertension (HTN). While linked with clinical observations, the mechanisms of vagal gut‐brain communication are not fully understood. Moreover, the role of the sub‐diaphragmatic gut‐projecting vagal nerve branches in control of blood pressure (BP) remains unclear. The objective of this study was to examine the systemic and central effects of augmenting vagus nerve activity using subdiaphragmatic vagus nerve stimulation (sdVNS) during the development of HTN in spontaneously hypertensive rat (SHR).MethodsMale SHR (8 wo) were implanted with BP telemeters and either a silicone cuff electrode (STIM, N=5) or sham cuff (SHAM, N=5) on the ventral subdiaphragmatic vagal trunk. Following recovery and baseline BP recordings, STIM rats were connected to a stimulus generator, and subjected to biphasic (600 μA, 500 us/phase, 25 Hz) vagus nerve stimulation (10 minutes/ session, 3 sessions/ day, 5 days/ week) for 7 weeks. SHAM rats were subjected to similar handling but with no stimulation. Blood pressure was recorded with a 24‐hour continuous recording once per week for eight weeks in all rats. Rats were sacrificed and cecal content, plasma, proximal colon, and nucleus tractus solitarius (NTS) were collected. Bacterial 16s sequencing was used to determine abundance and composition of gut bacteria. Inflammatory cytokines including INF‐γ, IL‐1β, IL‐4, IL‐5, IL‐6, KC/GRO, IL‐10, IL‐13, TNF‐α, IL‐17α, and corticosterone were measured in serum and proximal colon. To further discern mechanisms, the NTS transcriptome was measured at endpoint using RNA‐seq.ResultsIn SHAM SHR, both the mean BP (MBP) and diastolic BP (DBP) were significantly elevated in week one (ΔMBP= +13.6 mmHg, p = 0.01; ΔDBP= +11.5 mmHg, p = 0.03) when compared to baseline BP. In contrast, in STIM SHR, the MBP and DBP were not significantly elevated until week five of sdVNS (ΔMBP= +25.0 mmHg, p &lt; 0.001; ΔDBP= +20.8 mmHg, p &lt; 0.001) when compared to baseline BP. Systolic BP (SBP) values were similarly elevated compared to baseline at all time points examined. At endpoint, we observed no difference in any of the 11 proinflammatory cytokines measured in either plasma or colonic lysates between SHAM and STIM SHR. In addition, no difference was observed in the composition or abundance of major gut bacterial phyla. However, chronic intermittent sdVNS resulted in 387 up‐regulated and 236 down‐regulated genes in the NTS. Gene set enrichment analysis revealed differential regulation of central inflammatory and neural signaling pathways in the NTS of SHR following sdVNS.ConclusionsChronic intermittent sdVNS can delay but not prevent the onset of HTN in the SHR. This delay does not coincide with changes in systemic inflammatory markers or gut bacterial composition; however, changes in the NTS transcriptome indicate afferent rather than efferent effects of chronic intermittent sdVNS in the SHR. Future studies will dissect precise central effects of afferent gut‐brain communication.

Application of Vagus Nerve Branch Preservation in Thoracoscopic Surgery for Early-Stage Lung Cancer.

Background In this study, we introduced a novel surgical strategy to protect vagal nerve branches during radical thoracoscopic surgery in right lung cancer and explored the effects of vagal nerve branch preservation. Methods We retrospectively studied 53 patients with right-sided lung cancer with clinically staged T1N0M0 between 2019 and 2020. All 53 patients were treated with total thoracoscopic lobectomy and mediastinal lymph node dissection in the same number of lymph node stations. Of these, 22 patients adopted a vagus nerve branch protection strategy during lymph node dissection. Another 31 patients were treated with traditional lymph node dissection as the control group. Results The characteristics of the patients were similar between the two groups. The operation time and intraoperative bleeding in the protection group were longer than those in the control group. However, the protection group had a lower average postoperative pain score and average postoperative hospital stay. The above difference was not statistically significant. Three cases of arrhythmia occurred in the protection group, including 1 case of tachycardia and 2 cases of atrial fibrillation. In the control group, 13 cases of arrhythmia occurred after the operation, including 8 cases of tachycardia and 5 cases of atrial fibrillation. We also tracked changes in the patients' heart rates throughout the treatment process (excluding patients with arrhythmias). An increased heart rate was observed postoperatively in both groups, but the increase of heart rate of the protection group was smaller than that of the control group; however, the difference was not statistically significant. Conclusions A vagus nerve branch preservation-based approach to radical surgery is a safe and feasible strategy for right lung cancer treatment, which could significantly reduce the risk of postoperative arrhythmia in patients and may also have a potential role in reducing the length of hospital stay and maintaining heart rate stability in the postoperative period.

Transcutaneous Vagal Nerve Stimulation in Treatment-Resistant Depression: A Feasibility Study

BackgroundMajor depression (MD) contributes significantly to the global burden of disease with up to one-third of patients being treatment resistant. Therefore, the development of new treatment options for treatment-resistant depression (TRD) is needed. Vagus nerve stimulation (VNS) has shown mood improvements in patients with TRD. However, due to high costs related to the implantation and the invasive nature of VNS, an application with transcutaneous VNS (t-VNS) has been developed stimulating a vagal nerve branch in the earlobe (Arnold's nerve). A few studies with t-VNS in MD have shown a possible antidepressant effect, but feasibility is poorly described and patients with TRD have not been investigated. ObjectivesAs the full antidepressant effect of t-VNS takes months we wanted to assess feasibility and side effects of daily treatments. Materials and MethodsSingle-arm feasibility trial assessing compliance, usability, side effects, cognitive speed, and depression in a four-week period with a recommended t-VNS stimulation duration of four hours per day in patients with TRD. The primary outcome was compliance with 80% of the recommended daily treatment time. ResultsCompliance threshold was reached for 80.0% of the 20 included participants. Usability was acceptable. Side effects were few, mild or moderate, mostly as local effects at the contact point in the ear. The device was difficult to use for some participants. A statistically significant reduction in depression severity and an increase in cognitive speed were seen with unchanged suicidal ideation and sleep. ConclusionsWe would recommend larger long-term randomized studies of t-VNS to access any antidepressant effect in TRD. The design of the device might be improved for higher usability.

Effects of Preserving the Pulmonary Vagus Nerve Branches on Cough After Pneumonectomy During Video-Assisted Thoracic Surgery.

BackgroundCough is one of the most common complications of early-stage non-small cell lung cancer (NSCLC) after video-assisted thoracoscopic surgery (VATS). The vagus nerve plays an important role in pulmonary inflammation and the cough reflex. In this study, we attempted to reduce the incidence of postoperative chronic cough and other complications by preserving the pulmonary vagus nerve branches.Patients and MethodsThis study was a randomized controlled double-blinded trial of subjects and observers. A total of 158 NSCLC patients were enrolled. We randomly assigned 79 patients to Group A (pulmonary branch of vagus nerve preservation group) and 79 cases to Group B (conventional surgical treatment group). In the final analysis, 72 patients from Group A and 69 patients from Group B were included. The main outcome measure of the study was the occurrence of CAP or other postoperative complications within five weeks. This trial was registered with ClinicalTrials.gov (number NCT03921828).ResultsThere was no significant difference in preoperative general clinical data between the two groups. No death during the perioperative period occurred in either of the two groups. There was no significant difference between the two groups in operation time, intraoperative bleeding, number of lymph nodes sent for examination, number of cases transferred to ICU after operation, postoperative catheterization time, or postoperative hospital stay (P>0.05). There was no significant difference in other pulmonary and cardiovascular complications between the two groups, including pulmonary infection (2.78% vs. 8.70%, P = 0.129), atelectasis (1.39% vs. 0%, P = 0.326), pleural effusion (2.78% vs. 1.45%, P = 0.585), persistent pulmonary leakage (2.78% vs. 2.90%, P = 0.965), arrhythmia (2.78% vs. 1.45%, P = 0.585), and heart failure (0% vs. 1.45%, P = 0.305). The incidence of CAP in Group A was significantly lower than that in Group B (13.89% vs. 30.43%, P = 0.018). The LCQ-MC scores in Group A were significantly higher than those in Group B at two and five weeks after operation (P<0.05). Univariate and multivariate analysis showed that the risk factors for postoperative CAP were surgical side (right lung), surgical lung lobe (upper lobe), preservation of pulmonary branch of the vagus nerve during operation, and duration of anesthesia.ConclusionsPreserving the pulmonary vagus nerve branches during VATS in patients with stage IA1-2 NSCLC can reduce the incidence of postoperative CAP.

Reproducible asystole following vagal nerve stimulator lead replacement: a case report

BackgroundVagal nerve stimulation (VNS) is approved therapy for the treatment of intractable epilepsy. The stimulation of either nerve, left or right, is effective. However, due to the anatomic and physiological effects of cardiac innervation, the right vagus nerve is typically avoided in order to minimize the risk of cardiac bradyarrhythmias. The location of the VNS lead contacts on the nerve can also have an effect, namely, more distally placed contacts have been associated with lower risk of cardiac arrhythmias, presumably by avoiding vagal cervical cardiac branches; however, our case demonstrates reproducible asystole despite left sided, distal VNS lead placement.Case presentationWe report a 28-year-old male patient with pharmacoresistant generalized clonic-tonic seizures. The VNS therapy with 1.5 mA output and 16% duty cycle drastically reduced his seizure burden for several years. The breakthrough seizures along with stabbing pain episodes at the implantable pulse generator (IPG) site have prompted the VNS lead revision surgery with new lead contacts placed more caudally than the old contacts. However, the intraoperative device interrogation with 1 mA output resulted in immediate asystole for the duration of stimulation and it was reproducible until the output was decreased to 0.675 mA.ConclusionsOur case highlights the possibility of new severe cardiac bradyarrhythmias following surgical VNS lead replacements even in patients without preoperatively known clinical side effects. We suggest preoperative electrocardiography and cardiology consultation for detected abnormalities for all patients undergoing new VNS implantations, as well as revision surgeries for VNS malfunctions. Intraoperatively, the surgeon and anesthesia team should be vigilant of cardiac rhythms and prepared for the immediate management.

Laryngeal Muscle-Evoked Potential Recording as an Indicator of Vagal Nerve Fiber Activation

BackgroundVagus nerve stimulation (VNS) is an adjunctive therapy for drug-resistant epilepsy. Noninvasive evoked potential recordings in laryngeal muscles (LMEPs) innervated by vagal branches may provide a marker to assess effective vagal nerve fiber activation. We investigated VNS-induced LMEPs in patients with epilepsy in acute and chronic settings. Materials and MethodsA total of 17 of 25 patients underwent LMEP recordings at initiation of therapy (acute group); 15 of 25 patients after one year of VNS (chronic group); and 7 of 25 patients were tested at both time points (acute + chronic group). VNS-induced LMEPs were recorded following different pulse widths and output currents using six surface laryngeal EMG electrodes to calculate input/output curves and estimate LMEP latency, threshold current for minimal (Ithreshold), half-maximal (I50), and 95% of maximal (I95) response induction and amplitude of maximal response (Vmax). These were compared with the acute + chronic group and between responders and nonresponders in the acute and chronic group. ResultsVNS-induced LMEPs were present in all patients. Ithreshold and I95 values ranged from 0.25 to 1.00 mA and from 0.42 to 1.77 mA, respectively. Estimated mean LMEP latencies were 10 ± 0.1 milliseconds. No significant differences between responders and nonresponders were observed. In the acute + chronic group, Ithreshold values remained stable over time. However, at the individual level in this group, Vmax was lower in all patients after one year compared with baseline. ConclusionsNoninvasive VNS-induced LMEP recording is feasible both at initiation of VNS therapy and after one year. Low output currents (0.25–1.00 mA) may be sufficient to activate vagal Aα-motor fibers. Maximal LMEP amplitudes seemed to decrease after chronic VNS therapy in patients.

Cover Image

The cover image is based on the Education A novel method to reconstruct right recurrent laryngeal nerve by transforming into nonrecurrent laryngeal nerve: The end-to-free vagal laryngeal branch end anastomosis by Yu-Long Wang et al., https://doi.org/10.1002/hed.26942.

Non-Invasive Transcutaneous Vagus Nerve Stimulation for the Treatment of Fibromyalgia Symptoms: A Study Protocol.

Stimulation of the vagus nerve, a parasympathetic nerve that controls the neuro-digestive, vascular, and immune systems, induces pain relief, particularly in clinical conditions such as headache and rheumatoid arthritis. Transmission through vagal afferents towards the nucleus of the solitary tract (NST), the central relay nucleus of the vagus nerve, has been proposed as the main physiological mechanism that reduces pain intensity after vagal stimulation. Chronic pain symptoms of fibromyalgia patients might benefit from stimulation of the vagus nerve via normalization of altered autonomic and immune systems causing their respective symptoms. However, multi-session non-invasive vagal stimulation effects on fibromyalgia have not been evaluated in randomized clinical trials. We propose a parallel group, sham-controlled, randomized study to modulate the sympathetic–vagal balance and pain intensity in fibromyalgia patients by application of non-invasive transcutaneous vagus nerve stimulation (tVNS) over the vagal auricular and cervical branches. We will recruit 136 fibromyalgia patients with chronic moderate to high pain intensity. The primary outcome measure will be pain intensity, and secondary measures will be fatigue, health-related quality of life, sleep disorders, and depression. Heart rate variability and pro-inflammatory cytokine levels will be obtained as secondary physiological measures. We hypothesize that multiple tVNS sessions (five per week, for 4 weeks) will reduce pain intensity and improve quality of life as a result of normalization of the vagal control of nociception and immune–autonomic functions. Since both vagal branches project to the NST, we do not predict significantly different results between the two stimulation protocols.

Transcutaneous auricular vagus nerve stimulation cannot modulate the P3b event-related potential in healthy volunteers

ObjectiveThe release of cortical norepinephrine is one of the possible mechanisms of action of vagus nerve stimulation (VNS), a neuromodulatory treatment currently under investigation for cognitive impairment. Transcutaneous auricular VNS (taVNS) may be able to activate vagal nerve branches ending in the brainstem’s locus coeruleus (LC) non-invasively. The aim was to investigate if acute taVNS can modulate the P3b, a cognitive event-related potential (ERP) reflecting noradrenergic brain activation under control of the LC. MethodsThirty-nine healthy volunteers performed an auditory oddball task during no stimulation, sham stimulation and taVNS in a randomized order. P3b amplitude, latency and behavioral outcome parameters were compared between conditions using linear mixed models. ResultsP3b amplitude and latency during taVNS did not differ significantly from sham or control. Reaction time shortened and P3b latency prolonged with repetition of the oddball task. ConclusionsWe were unable to modulate cognitive ERPs by means of acute taVNS in a large group of healthy volunteers. SignificanceTargeting vagal nerve fibres via a transcutaneous approach did not alter the P3b in healthy participants. The stimulation parameters used and transient delivery of taVNS might be insufficient to adequately modulate the LC. Also, a disbalanced locus coeruleus - norepinephrine system in patients may be more prone for improvement.

Preemptive pyloroplasty for iatrogenic vagus nerve injury in intrahepatic cholangiocarcinoma patients undergoing extensive left-sided lymph node dissection: a retrospective observational study.

BackgroundIntrahepatic cholangiocarcinoma (ICC) of the left liver often shows left-sided lymph node (LN) metastasis. If gastric lesser curvature is extensively dissected, it can induce an iatrogenic injury to the extragastric vagus nerve branches that control motility of the pyloric sphincter and lead to gastric stasis. To cope with such LN dissection-associated gastric stasis, we performed pyloroplasty preemptively. The objective of this study was to analyze our 20-year experience of preemptive pyloroplasty performed in 10 patients.MethodsWe investigated clinical sequences of 10 patients with ICC who underwent preemptive pyloroplasty following left hepatectomy and extended left-sided LN dissection. Incidence of gastric stasis and oncological survival outcomes were analyzed.ResultsAll 10 patients were classified as stage IIIB due to T1-3N1M0 stage according to the 8th edition of American Joint Committee on Cancer staging system. The overall patient survival rate was 51.9% at 1 year, 25.9% at 2 years, and 0% at 3 years. Seven patients showed uneventful postoperative recovery after surgery. Two patients suffered from gastric stasis, which was successfully managed with supportive care. One patient suffered from overt gastric paresis, which was successfully managed with azithromycin administration for 1 month.ConclusionWe believe that preemptive pyloroplasty is an effective surgical option to prevent gastric stasis in patients undergoing extensive left-sided LN dissection. Azithromycin appears to be a potent prokinetic agent in gastroparesis.