Effects of Electrical Transcutaneous Vagus Nerve Stimulation on the Perceived Intensity of Repetitive Painful Heat Stimuli: A Blinded Placebo- and Sham-Controlled Randomized Crossover Investigation
Bibliographic record
Abstract
BACKGROUND: Transcutaneous vagus nerve stimulation (TVNS) is a promising treatment for acute and chronic pain. However, experimental studies yielded controversial results. We examined if TVNS reduces the perceived intensity of repetitive painful heat stimulation and temporal summation of pain (TSP) in healthy volunteers in comparison with placebo and sham stimulation, as well as no intervention. METHODS: In 4 sessions, 90 heat pulse stimuli at individual pain tolerance temperature were applied to the ventral forearm of 49 healthy volunteers (25 women) using a Contact Heat Evoked Potential Stimulator thermode (Medoc, Ramat Yishai, Israel). Pain intensity was assessed with verbal ratings on a numeric pain scale (0-100) at every tenth heat pulse. After the first session in which pain intensities without intervention were evaluated, participants completed 3 sessions in a single-blinded randomized crossover manner: (1) sham stimulation applied at the earlobes, (2) placebo stimulation (inactive device), or (3) TVNS applied at the cymbas conchae. Primary data were analyzed using analysis of variance for repeated measures and t test for paired samples. RESULTS: Pain intensity decreased during all interventions as compared to no intervention (ηp = 0.22, P < .001; mean difference TVNS versus no intervention 9.5; 95% confidence interval [CI], 3.6-15.4; P < .001). Hypoalgesic effect of TVNS was better than that of placebo and sham in men before the onset of TSP (mean differences for TVNS versus placebo 6.2; 95% CI, 0.2-12.1; TVNS versus sham 6.2; 95% CI, 0.2-12.1; P < .05). In women, TSP response under TVNS was decreased if compared to no intervention (median difference, 7.5; 95% CI, 3.5-15.0; P = .003). CONCLUSIONS: TVNS, placebo, and sham stimulation exerted comparable effects under experimental heat pain stimulation. Only in male participants, TVNS was superior to sham and placebo conditions in the reduction of heat pain before the onset of TSP.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".