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A new concept for transcutaneous vagus nerve stimulation for control of partial onset seizures is described. The rationale for the application of this innovative noninvasive method is discussed.
INTRODUCTION: Transcutaneous auricular vagus nerve stimulation (tVNS) has shown potential in neurological, autoimmune, and cardiovascular disorders, but its effects on HD patients remain unclear. This study aimed to evaluate the efficacy and safety of tVNS in HD patients. METHODS: We conducted a randomized controlled clinical trial on patients receiving HD ≥6 months. The tVNS group received stimulation for 1 h during the first 2 h of HD sessions, three times weekly for 8 weeks, while the control group received standard care. The primary outcomes were dialysis efficiency (Single-pool Kt/V, Sp Kt/V) and dialysis-related symptoms (Dialysis Symptom Index, DSI), assessed every 4 weeks. Secondary outcomes included pain and fatigue scores, physical performance, Hemodialysis Comfort Scale, hemoglobin levels, Mini-Mental State Examination, and anxiety and depression scores, measured at baseline and 8 weeks after intervention. RESULTS: A total of 63 patients were enrolled in the study, with 32 patients assigned to the tVNS group and 31 patients to the control group. At 8 weeks, the tVNS group showed significant improvements in Sp Kt/V (1.31 ± 0.11 vs. 1.25 ± 0.10, p = 0.02), and DSI (12.09 ± 5.84 vs. 16.26 ± 5.27, p = 0.004), as well as reductions in pain and fatigue, and increases in physical function, comfort, and hemoglobin. However, there were no statistically significant changes observed in cognitive function, anxiety, or depression. CONCLUSIONS: tVNS could improve dialysis efficiency, symptoms, and physical function in HD patients, indicating it may have a role as a complementary therapy.
Impairments in sleep quality, timing, or duration disrupt normal sleep patterns. This systematic review and meta-analysis investigated the effects of transcutaneous vagus nerve stimulation (tVNS) protocols on sleep outcomes. Thirteen randomized controlled trials with parallel or crossover designs that applied tVNS intervention and assessed sleep quality (Pittsburgh Sleep Quality Index) and insomnia severity (Athens Insomnia Scale and Insomnia Severity Index) were included. Effect sizes were calculated by comparing changes between the active tVNS and control groups. Moderator analyses examined whether stimulation of different targeted regions influences sleep outcomes. Meta-regression analyses examined potential relationships between the effects of tVNS protocols on sleep quality and demographic characteristics and multiple tVNS parameters, respectively. The random-effects meta-analysis indicated that tVNS protocols influenced better sleep quality and lower insomnia severity. Moderator variable analysis revealed that tVNS targeting the concha region induced better sleep quality. Meta-regression analysis revealed that better sleep quality was associated with lower ages of participants. These findings suggest that tVNS protocols, particularly those targeting the concha, were associated with favorable changes in sleep quality and insomnia severity, with age potentially moderating the treatment response.
Recently, a new electrophysiological method for the assessment of vagus nerve function in the brainstem has been proposed in healthy participants. Before this procedure may be applied to patients with neurodegenerative diseases, its feasibility in elderly healthy participants and a possible age effect on the measurement have to be investigated. The vagus sensory evoked potentials (VSEP) after transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve have been assessed in healthy younger and elderly participants. VSEP measured as far field potentials probably originating in vagus nuclei in the brainstem were recorded in 20 of 22 younger as well as in 39 of 43 elderly healthy participants. Latencies were significantly longer in the elderly as compared to the younger participants, while no clear age effects on amplitudes were identified. These results indicate that the assessment of VSEP is feasible also in elderly healthy participants. This is a prerequisite for testing this method in elderly patients with neurodegenerative diseases like Alzheimer and Parkinson disease as a noninvasive tool to detect an affection of the brainstem nuclei of the vagus nerve early in their course.
Recently, the vagus nerve has gained particular interest in neuropsychiatry, as neurodegenerative diseases like Alzheimer's and Parkinson's disease are supposed to affect the brainstem nuclei of the vagus nerve early in their course. In addition, electric stimulation of the vagus nerve has therapeutic effects in otherwise therapy-refractory epilepsies and depressions. So far, no method is available to assess vagus nerve function in this context. On this background and based on the established techniques of early acoustic evoked potentials we investigated if a transcutaneous electric stimulation of the sensory auricular branch of the vagus nerve innervating parts of the outer ear is feasible in healthy subjects using this hypothesis-generated approach. We were able to record a clear, reproducible Vagus Sensory Evoked Potential (VSEP) measured as far field potential probably originating in vagus nuclei in the brainstem. Further studies are needed to test the interindividual stability and test-retest reliability of this new method before potential diagnostic and therapeutic applications might be evaluated.
Objective: To evaluate the efficacy and safety of transcutaneous auricular vagus nerve stimulation (taVNS) during the acute phase in middle-aged and elderly patients with herpes zoster (HZ) comorbid depressive and anxiety states. Methods: This was a randomized controlled trial. Forty middle-aged and elderly patients with acute-phase HZ who attended the Department of Dermatology at Xuanwu Hospital, Capital Medical University, from June 2024 to June 2025 were enrolled and randomly assigned in a 1∶1 ratio using a random number table to receive either taVNS (n=20) or sham stimulation (n=20) for 5 consecutive days. Both groups received antiviral therapy and on-demand rescue analgesia. Pain, anxiety/depression, and sleep quality were evaluated using the Visual Analog Scale (VAS), the 4-item Patient Health Questionnaire (PHQ-4), and the Insomnia Severity Index (ISI), respectively. The primary outcome was the incidence of subacute pain at 30 days post-rash onset. Secondary outcomes included cumulative analgesic consumption at 1 and 2 weeks after treatment, the changes from baseline (Δ values) in PHQ-4 and ISI scores at 2 weeks, and the incidence of postherpetic neuralgia (PHN) at 90 days post-rash onset. Results: In the taVNS group, 7 patients (35%) were female, with a mean age of (64.1±9.7) years; in the sham group, 10 patients (50%) were female, with a mean age of (61.5±8.5) years. There were no statistically significant differences between the two groups in baseline VAS, PHQ-4, or ISI scores (all P>0.05). The incidence of subacute pain was significantly lower in the taVNS group than in the sham group [5% (1/20) vs 35% (7/20), RD=-30.0% (95%CI:-52.1%--4.9%); RR=0.14 (95%CI: 0.02-1.06); P=0.044]. At 2 weeks after treatment, the Δ values of PHQ-4 and ISI in the taVNS group were significantly greater than those in the sham group. The proportion of patients taking Lofentadine and the cumulative Lofentadine consumption at weeks 1 and 2 were both lower in the taVNS group than in the sham group (all P<0.05). No serious adverse events occurred in either group, and the difference in PHN incidence between groups was not statistically significant (P>0.05). Conclusions: Acute-phase taVNS appears to be feasible and safe in middle-aged and elderly patients with HZ and comorbid depressive and anxiety, effectively reducing subacute pain and improving emotional and sleep outcomes.
BACKGROUND: Patients with functional dyspepsia (FD) and irritable bowel syndrome (IBS) often experience abdominal pain and reduced quality of life and need effective treatments. This exploratory study aimed to evaluate whether transcutaneous auricular vagus nerve stimulation (taVNS) could improve abdominal pain and quality of life in patients with FD and IBS, and whether the effects were mediated via the autonomic mechanisms. METHODS: A total of 64 patients with abdominal pain (43 FD and 21 IBS) with a pain score of 3 out of 10 or higher were randomized to receive 2 weeks of taVNS or sham-taVNS treatment. The primary outcome was numeric rating scale (NRS) for abdominal pain. The dyspeptic symptom scales (DSS), IBS symptom severity scale score (IBS-SSS), anxiety and depression scores, and the SF36 quality of life scale were assessed before and after the treatment. The electrocardiogram was also recorded for the assessment of autonomic function at baseline and after the treatment. KEY RESULTS: (1) taVNS reduced the abdominal pain score (p < 0.001 for both FD and IBS), the frequency of abdominal pain (p < 0.001 for both FD and IBS), and overall symptom scores in both FD patients and IBS patients (p < 0.001 for FD and IBS). There was no significant difference in the effect of taVNS on abdominal pain between FD and IBS patients. (2) taVNS improved quality of life compared with baseline in both FD and IBS patients. (3) taVNS decreased anxiety (p < 0.001) and depression (p < 0.001). (4) taVNS increased vagal activity. At the end of the taVNS treatment, the vagal activity was negatively correlated with the pain score (r = -0.491, p = 0.004). CONCLUSIONS: Non-invasive taVNS improves abdominal pain, quality of life, and anxiety and depression in patients with FD and patients with IBS, possibly attributed to the enhancement of vagal activity. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR2400085697.
BACKGROUND: Postoperative pain after thoracic surgery remains common and challenging. Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive neuromodulation technique with potential analgesic effects. This study aimed to evaluate the efficacy and safety of taVNS for postoperative pain management in patients undergoing thoracoscopic partial lung resection. METHODS: Adults undergoing thoracoscopic partial lung resection were randomized to active or sham taVNS. The primary outcome was cough pain intensity at 48h post-surgery, assessed by Numeric Rating Scale (NRS). Secondary outcomes included cough pain at 24h and 72h, resting pain, moderate-to-severe pain incidence, opioid consumption, quality of recovery, postoperative pulmonary complications , chest tube duration, hospital stay, postoperative nausea/vomiting, and adverse events. RESULTS: Among 119 analyzed patients (active n = 60, sham n = 59), active taVNS reduced cough pain scores at 24h, 48h, and 72h postoperatively, as well as resting pain (p < 0.05). It also lowered the incidence of moderate-to-severe cough pain at 24h and 48h, reduced cumulative postoperative opioid use at 24h and 72h, and decreased rescue analgesia on postoperative day 3 (p < 0.05). Active taVNS was associated with a lower incidence of postoperative pneumothorax (p < 0.05). No serious adverse events occurred. CONCLUSION: Perioperative taVNS was associated with a modest analgesic benefit and reduced postoperative opioid requirements after thoracoscopic partial lung resection. The observed reduction in postoperative pneumothorax requires cautious interpretation, and further multicenter trials are needed to determine its clinical utility.
Anhedonia, a core feature of major depressive disorder, is associated with disrupted reward processing and may represent a mechanistically relevant target for neuromodulation. This study examined the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on reward-related behavior and autonomic regulation in individuals with higher (n = 34) and lower (n = 34) depressive symptomatology. In a randomized, within-subject crossover design, participants received active taVNS and sham stimulation on two separate days. During each session, incentive motivation and reward learning were assessed using the Effort Expenditure for Rewards Task and the Probabilistic Reward Task (PRT), respectively, with stimulation condition and task order counterbalanced. Findings revealed that taVNS effects on heart rate variability (HRV) were modulated by baseline HRV levels and depressive status; specifically, they enhanced HRV at low baseline levels and reduced it at high baseline levels in participants with lower depressive symptomatology, with opposite patterns in individuals with higher symptoms. Moreover, compared to sham, taVNS enhanced the willingness to exert effort for rewards, particularly at low reward probabilities, with a more pronounced effect in the group characterized by higher depressive symptoms. No significant effects were observed on reward learning, as indexed by the PRT. Additionally, taVNS reduced self-reported anxiety across groups. Despite the limitation of a single stimulation session, these findings suggest that taVNS modulates motivational effort allocation in individuals with higher depressive symptoms, supporting its potential relevance for targeting reward-related dysfunctions in mood disorders.
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The efficacy of electrical defibrillation is considered to be related to the autonomic status. In search of a possible adjunct to enhance the therapeutic performance of an implantable cardioverter-defibrillator. we investigated whether parasympathetic manipulation by cervical vagal nerve stimulation (VNS) increases defibrillation efficacy. The effects of VNS on transcardiac defibrillation threshold (DFT) were assessed in 55 anesthetized dogs. In neurally intact dogs, right and left unilateral VNS at 10 mA for 7 seconds significantly decreased the DFT after 10 seconds of ventricular fibrillation (control: 3.1 +/- 0.9 J, right: 2.1 +/- 0.9 J [delta-35 +/- 12%, P < 0.0001], left: 2.2 +/- 0.8 J [delta-31 +/- 11%, P < 0.0005]), while bilateral VNS did not (2.8 +/- 1.0 J). In dogs with decentralized vagus nerves, both unilateral and bilateral VNS decreased the DFT. The extent of the VNS-induced decrease in DFT was dependent on the current and the duration of stimulation. We conclude that unilateral VNS decreases the DFT, while bilateral VNS paradoxically has no effect on the DFT unless the vagi are decentralized.
The goal of the treatment of epilepsy is to eliminate seizures while causing no side effects. For persons whose seizures are refractory, epilepsy surgery may be an option. In addition, these patients may benefit from the vagus nerve stimulator (VNS), the first device approved for the treatment of refractory epilepsy. Although VNS was the first to be approved, investigators have been interested in the effectiveness of stimulating other brain regions: the cerebellum, thalamus, subthalamic nucleus, and locus coeruleus are a few examples. These studies have produced mixed results. As our understanding of the underlying mechanisms of epilepsy grows, it is likely that we will design better and more effective devices for the treatment of epilepsy.
In the trachea and bronchi of the atropinized rat, the proportion of degranulating mast cells (defined as having one or more granules outside the body of the cell in a 10-microns thick section) was increased from 35-40% to 48-55% following electrical stimulation of one or both vagus nerves for 3 min. The increase occurred bilaterally, though it was greater on the stimulated side. The degranulation of mast cells was prevented by transection of the nerve rostral to the nodose ganglion 8-10 days before stimulation. Pre-treatment of rats with capsaicin also prevented the degranulation of mast cells that otherwise would have followed stimulation of the vagus nerve. These observations indicate that tracheo-bronchial mast cells discharge their granules in response to the activity of capsaicin-sensitive axons of neurons whose cell bodies are rostral to the nodose ganglion. These are probably substance P-containing polymodal nociceptive neurons of the jugular ganglion. If similar neurons exist in man, axon reflexes in their intrabronchial branches would be expected to stimulate the release of mast cell-derived agents that cause bronchoconstriction in asthma.
The antiepileptic medication and surgical treatment had brought many patients with epilepsy to be seizure free, however, one third of the patients continue to experience seizures. There has recently been an explosion of research into brain stimulation for treating these intractable epilepsy patients. This is largely due to the success of deep brain stimulation of movement disorders. The intelligent cardiac pacemakers also stimulated the neurosurgeons to utilize the implantable devices. In this paper, brain stimulations with vagus nerve stimulator (VNS), depth electrodes, subdural electrodes, external responsive neuro-stimulator, implantable brain stimulator and transcranial magnetic stimulator are reviewed. The VNS had been approved in Europe and United States for clinical use. The efficacy of the VNS has already proven by the controlled trials. Stimulation of the thalamus, subthalamic nucleus and hippocampus showed some efficacy in a small number of patients, however, large scale traials remains to be undertaken. External responsive neurostimulator has shown efficacy and safety to justify further studies with implantable brain stimulators. The multi-center cooperative study is ongoing in the US to examine the usefulness of the implantable stimulator. Animal studies showed efficacy of the transcranial magnetic stimulation for the treatment and prevention of the seizures and status epilepticus.
Abnormalities in regional cerebral blood flow (rCBF) have been reported to characterize depressive episodes; they are at least partly reversed by antidepressant treatment. Treatment-specific as well as response-related changes in rCBF have been reported. We explored the changes in rCBF induced by vagus nerve stimulation (VNS), a recently proposed antidepressant strategy, by application of single photon emission-computed tomography with (99m)Tc-hexamethyl-propylene amine oxime in otherwise treatment-refractory patients. Both region-of-interest (ROI) and statistical parametric mapping (SPM) analytic approaches were used. Decreases of rCBF in the amygdala, left hippocampus, left subgenual cingulate cortex, left and right ventral anterior cingulum, right thalamus and brain stem were observed; the only increase of rCBF was found by SPM analysis in the middle frontal gyrus. This pattern shares features with changes of rCBF previously associated with the administration of selective serotonin reuptake inhibitors. Similarities to other brain-stimulation strategies in antidepressant treatment were less pronounced.
BACKGROUND: Given that vagal afferents project to brainstem regions that promote alertness, the authors tested the hypothesis that vagus nerve stimulation (VNS) would improve daytime sleepiness in patients with epilepsy. METHODS: Sixteen subjects with medically refractory seizures underwent polysomnography and multiple sleep latency tests (MSLT) and completed the Epworth Sleepiness Scale (ESS), a measure of subjective daytime sleepiness, before and after 3 months of VNS. Most subjects (>80%) were maintained on constant doses of antiepileptic medications. RESULTS: In the 15 subjects who completed baseline and treatment MSLT, the mean sleep latency (MSL) improved from 6.4 +/- 4.1 minutes to 9.8 +/- 5.8 minutes (+/- SD; p = 0.033), indicating reduced daytime sleepiness. All subjects with stimulus intensities of < or =1.5 mA showed improved MSL. In the 16 subjects who completed baseline and treatment ESS, the mean ESS score decreased from 7.2 +/- 4.4 to 5.6 +/- 4.5 points (p = 0.049). Improvements in MSLT and ESS were not correlated with reduction in seizure frequency. Sleep-onset REM periods occurred more frequently in treatment naps as compared to baseline naps (p < 0.008; Cochran-Mantel-Haenszel test). The amount of REM sleep or other sleep stages recorded on overnight polysomnography did not change with VNS treatment. CONCLUSIONS: Treatment with VNS at low stimulus intensities improves daytime sleepiness, even in subjects without reductions in seizure frequency. Daytime REM sleep is enhanced with VNS. These findings support the role of VNS in activating cholinergic and other brain regions that promote alertness.
The effects of the phase of respiration on the response of respiratory cardiac cycle variability to sensory stimulation were studied in five healthy young male subjects. Transcutaneous electrical stimulation of the ulnar nerve or hand-grip exercise was applied during inspiration or expiration. Although both electrical stimulation and hand-grip exercise depressed respiratory cardiac cycle variability, the nature of the depression differed according to where in the respiration cycle the stimuli were applied. The amplitude of respiratory cardiac cycle variation was significantly decreased when either stimulus was applied during expiration (P < 0.05), and was unchanged when applied during inspiration (P > 0.05). These findings would suggest that cardiac vagal efferent activity was effectively inhibited by sensory stimulation during expiration, but was not inhibited by such stimulation during inspiration. This mechanism may account, in part, for the known suppression of respiratory cardiac cycle variability during exercise.