A Randomized, Double-Blind, Sham-Controlled, Clinical Trial of Auricular Vagus Nerve Stimulation for the Treatment of Active Rheumatoid Arthritis.

OBJECTIVE: Preliminary evidence suggests that vagus nerve stimulation (VNS) may have some benefit in patients with rheumatoid arthritis (RA); however, prior studies have been small and/or uncontrolled; this study aimed to address that gap. METHODS: This randomized, double-blind, sham-controlled trial enrolled patients aged 18 to 75 years with active RA who had failed conventional synthetic disease-modifying antirheumatic drugs (DMARDs) and were naïve to biologic and/or targeted synthetic DMARDs. All patients received an auricular vagus nerve stimulator and were randomized 1:1 to active stimulation or sham. The primary endpoint was the proportion of patients achieving 20% improvement in American College of Rheumatology criteria (ACR20) at week 12. Secondary endpoints included mean changes in disease activity score of 28 joints with C-reactive protein (DAS28-CRP) and Health Assessment Questionnaire-Disability Index (HAQ-DI). RESULTS: A total of 113 patients (mean age 54 years; 82% female) enrolled, and 101 patients (89.4%) completed week 12. ACR20 response at week 12 was 25.0% for active stimulation versus 26.9% for sham (difference vs. sham, -1.9; 95% CI, -18.8, 14.9, P = 0.823). The least square mean ± SE change in DAS28-CRP was -0.95 ± 0.16 for active stimulation and -0.66 ± 0.16 for sham (P = 0.201); in HAQ-DI it was -0.19 ± 0.06 for active stimulation and -0.02 ± 0.06 for sham (P = 0.044). Adverse events occurred in 17 patients (15%); all were mild or moderate. CONCLUSION: Auricular VNS did not meaningfully improve RA disease activity. If VNS with other modalities is pursued in the future for the treatment of RA, larger, controlled studies will be needed to understand its utility.

Effect of transcutaneous auricular vagus nerve stimulation on major depressive disorder with peripartum onset: A multicenter, open-label, controlled proof-of-concept clinical trial (DELOS-1).

BACKGROUND: Postpartum depression has a high prevalence in the United States (~13 %) and often goes undertreated/untreated. We conducted a multicenter, open-label, proof-of-concept trial to assess the Nesos wearable, non-invasive, transcutaneous auricular vagus nerve stimulation (taVNS) system for the treatment of major depressive disorder with peripartum onset (PPD). METHODS: Women (n = 25), ages 18 to 45, within 9 months postpartum, and diagnosed with PPD were enrolled at 3 sites. The study included 6 weeks open-label therapy and 2 weeks observation. Efficacy outcomes included change from baseline (CFB) in Hamilton Rating Scale for Depression (HAMD17) total scores, HAM-D17 response and remission, and patient and clinician global impression of change (PGIC, CGIC) scores. Analysis included descriptive statistics and mixed-effects models for repeated measures. RESULTS: The most common AEs (≥5 %) were discomfort (n = 5), headache (n = 3), and dizziness (n = 2); all resolved without intervention. No serious AEs or deaths occurred. Baseline mean HAM-D17 score was 18.4. Week 6 least squares (LS) mean CFB in HAM-D17 score was -9.7; 74 % achieved response and 61 % achieved remission. At week 6, at least some improvement was reported by 21 of 22 (95 %) clinicians on CGIC and 22 of 23 (96 %) participants on PGIC. LIMITATIONS: This was a single-arm, open-label study, and enrollment was limited to participants with mild-to-moderate peripartum depression. CONCLUSION: Results from this proof-of-concept study suggest that the Nesos taVNS system is well tolerated and may be an effective non-invasive, non-pharmacological treatment for major depressive disorder with peripartum onset. Further evaluation in larger sham-controlled studies is needed. CLINICALTRIALS: govNCT03972995.

Effects of Sub-threshold Transcutaneous Auricular Vagus Nerve Stimulation on Cingulate Cortex and Insula Resting-state Functional Connectivity.

Transcutaneous auricular vagus nerve stimulation (taVNS), a non-invasive alternative to vagus nerve stimulation (VNS) with implantable devices, has shown promise in treating disorders such as depression, migraine, and insomnia. Studies of these disorders with resting-state functional magnetic resonance imaging (MRI) (rsfMRI) have found sustained changes in resting-state functional connectivity (rsFC) in patients treated with low frequency (1-20 Hz) taVNS. A recent study has reported reductions in pain scores in patients with rheumatoid arthritis after a 12-week treatment of high-frequency (20 kHz) sub-threshold taVNS. However, no studies to date have examined the effects of high-frequency sub-threshold taVNS on rsFC. The objective of this study was to determine whether high-frequency sub-threshold taVNS induces changes in rsFC using seed regions from the cingulate cortex and insula, brain regions that play a key role in interoception and processing of pain. With a single-blind placebo-controlled repeated measures experimental design, rsfMRI scans were acquired before and after 15 min of either sub-threshold taVNS treatment or a sham control. Significant taVNS-related changes in functional connections to the cingulate cortex were detected between the anterior cingulate cortex and right superior temporal gyrus and between the midcingulate cortex and right inferior parietal lobule. In addition, significant changes in functional connections to the insula were detected between the posterior insula and right precuneus and between the anterior insula and right cuneus gyrus. These results suggest that high-frequency sub-threshold taVNS can lead to sustained effects on the rsFC of brain regions involved in interoception and processing of pain in a cohort of healthy subjects. This study lays the foundation for future rsfMRI studies of high-frequency sub-threshold taVNS in clinical populations.

Effects of sub-threshold transcutaneous auricular vagus nerve stimulation on cerebral blood flow.

Transcutaneous auricular vagus nerve stimulation (taVNS) has shown promise as a non-invasive alternative to vagus nerve stimulation (VNS) with implantable devices, which has been used to treat drug-resistant epilepsy and treatment-resistant depression. Prior work has used functional MRI to investigate the brain response to taVNS, and more recent work has also demonstrated potential therapeutic effects of high-frequency sub-threshold taVNS in rheumatoid arthritis. However, no studies to date have measured the effects of high-frequency sub-threshold taVNS on cerebral blood flow (CBF). The objective of this study was to determine whether high-frequency (20 kHz) sub-threshold taVNS induces significant changes in CBF, a promising metric for the assessment of the sustained effects of taVNS. Arterial spin labeling (ASL) MRI scans were performed on 20 healthy subjects in a single-blind placebo-controlled repeated measures experimental design. The ASL scans were performed before and after 15 min of either sub-threshold taVNS treatment or a sham control. taVNS induced significant changes in CBF in the superior posterior cerebellum that were largely localized to bilateral Crus I and Crus II. Post hoc analyses showed that the changes were driven by a treatment-related decrease in CBF. Fifteen minutes of high-frequency sub-threshold taVNS can induce sustained CBF decreases in the bilateral posterior cerebellum in a cohort of healthy subjects. This study lays the foundation for future studies in clinical populations, and also supports the use of ASL measures of CBF for the assessment of the sustained effects of taVNS.

Non-invasive vagus nerve stimulation for rheumatoid arthritis: a proof-of-concept study.

BACKGROUND: Vagus nerve stimulation delivered with an implanted device has been shown to improve rheumatoid arthritis severity. We aimed to investigate the safety and efficacy of non-invasive stimulation of the auricular branch of the vagus nerve for the treatment of patients with moderately to severely active rheumatoid arthritis. METHODS: This prospective, multicentre, open-label, single-arm proof-of-concept study enrolled patients aged 18-80 years with active rheumatoid arthritis who had an inadequate response to conventional synthetic disease-modifying antirheumatic drugs (DMARDs) and up to one biological DMARD. Biological DMARDs were stopped at least 4 weeks before enrolment and concomitant use was not allowed during the study. All eligible participants were assigned to use a non-invasive, wearable vagus nerve stimulation device for up to 30 min per day, which delivered pulses of 20 kHz. Follow-up visits occurred at week 1, week 2, week 4, week 8, and week 12 after the baseline visit. The primary endpoint was the mean change in Disease Activity Score of 28 joints with C-reactive protein (DAS28-CRP) at week 12 compared with baseline. Secondary endpoints included the mean change in the Health Assessment Questionnaire-Disability Index (HAQ-DI), the proportion of patients with a minimal clinically important difference of 0·22 on HAQ-DI, the proportion achieving American College of Rheumatology (ACR) 20, ACR50, and ACR70 response, and safety analysis. This study is registered with ClinicalTrials.gov (NCT04116866). FINDINGS: Of 35 patients screened for eligibility, 30 (86%) were enrolled at six centres in Spain between Dec 27, 2018, and Oct 24, 2019, of whom 27 (90%) completed the week 12 visit. The mean change in DAS28-CRP at 12 weeks was -1·4 (95%CI -1·9 to -0·9; p<0·0001) from a mean baseline of 5·3 (SD 1·0). 11 (37%) of 30 patients reached DAS28-CRP of 3·2 or less, and seven (23%) patients reached DAS28-CRP of less than 2·6 at week 12. The mean HAQ-DI change was -0·5 (95%CI -0·7 to -0·2; p<0·0001) from a mean baseline of 1·6 (SD 0·7), and 17 (57%) patients reached a minimal clinically important difference of 0·22 or more. ACR20 responses were reached by 16 (53%) patients, ACR50 responses by 10 (33%) patients, and ACR70 by five (17%) patients. Four adverse events were reported, none of which were serious and all of which resolved without intervention. INTERPRETATION: Use of the device was well tolerated, and patients had clinically meaningful reductions in DAS28-CRP. This was an uncontrolled, open-label study, and the results must be interpreted in this context. Further evaluation in larger, controlled studies is needed to confirm whether this non-invasive approach might offer an alternative treatment for rheumatoid arthritis. FUNDING: Nesos.

Effect of high-frequency alternating current on spinal afferent nociceptive transmission.

OBJECTIVE: The study was performed to test the hypothesis that high-frequency alternating current (HFAC) ranging from 2 to 100 kHz delivered to the spinal dorsal roots reduces activity of spinal wide dynamic range (WDR) dorsal horn neurons (DHNs) during noxious peripheral stimulation. MATERIALS AND METHODS: This hypothesis was tested in both small and large animal in vivo preparations. Single-unit extracellular spinal DHN recordings were performed in seven adult rats and four adult goats while testing various parameters of HFAC delivered to the nerve roots or dorsal root entry zone using various electrode types. Frequencies tested ranged from 2 to 100 kHz but focused on the 3 to 50 kHz range. This study investigated the ability of HFAC to inhibit WDR neuronal activity evoked by noxious mechanical (pinch), and electrical stimuli was tested but was primarily focused on electrical stimulation. RESULTS: Rat Study: Effects of HFAC were successfully tested on 11 WDR neurons. Suppression or complete blockade of evoked activity was observed in all 11 of these neurons. Complete data sets for neurons systematically tested with 15 baseline and post-HFAC stimulus sweeps were obtained in five neurons, the nociceptive activity of which was suppressed by an average of 69 ± 9.7% (p < 0.0001). Goat Study: HFAC was successfully tested on 15 WDR neurons. Conclusive suppression or complete nociceptive blockade was observed for 12/15 and complete data sets with at least 20 baseline and post-HFAC stimulus sweeps were obtained from eight DHNs. For these neurons the mean activity suppression was 70 ± 10% (p < 0.005). CONCLUSIONS: Delivery of HFAC to the region of epidural nerve root or nerve root entry inhibited afferent nociceptive input and therefore may have potential to serve as an alternative to traditional spinal cord stimulation without sensory paresthesia as neuronal activation cannot occur at frequencies in this range.