TaVNS for Capsaicin-Induced Pain

NCT07719868 | Not Yet Recruiting

• 1 other identifier: 2025-1505
• Study Type: interventional
• Target: 30
• Locations: 0 countries
• Sites: N/A

Brief Summary

Effective pain management remains a major clinical challenge. Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a promising, non-invasive neuromodulation technique due to its safety, ease of administration, and cost-effectiveness. Preliminary evidence suggests that taVNS exerts analgesic effects by activating afferent vagal fibers, which integrate signals in key central nodes such as the nucleus tractus solitarius (NTS). This process subsequently modulates pain-processing networks, neurotransmitter balance, inflammatory responses, and autonomic function. Despite its potential, the precise central neural mechanisms underlying taVNS-induced analgesia remain unclear, limiting the optimization of stimulation parameters (e.g., intensity, frequency, and target specificity) and the enhancement of long-term therapeutic outcomes. Previous studies have highlighted the role of taVNS in activating descending pain inhibitory pathways and modulating the limbic system, yet a comprehensive understanding of the causal neurophysiological dynamics is still lacking. This study aims to investigate the analgesic efficacy of taVNS using a capsaicin-induced pain model. Furthermore, by employing Transcranial Magnetic Stimulation combined with Electroencephalography (TMS-EEG), we seek to elucidate the central neural mechanisms of taVNS. By integrating causal intervention with high-temporal resolution brain activity recording, this research will provide scientific insights into the modulation of pain-related pathways-such as descending inhibitory and cognitive-affective networks-ultimately facilitating the development of standardized, individualized, and precise clinical interventions for pain management.

Conditions

Pain Management; Capsaicin-Induced Pain; Transcranial Magnetic Stimulation Repetitive; Electroencephalography; Neuromodulation; Analgesia; Vagus Nerve Stimulation

Outcome Measures

Primary Outcomes (1)

• Pain Intensity

  Measured using the Visual Analog Scale (VAS).

  Baseline and every 10 minutes up to 90 minutes post-capsaicin application.

Secondary Outcomes (4)

• Neural Plasticity and Brain Activity

  Baseline (pre-intervention), 40 minutes, and 90 minutes post-capsaicin application.

• Brain Network Connectivity

  Baseline (pre-intervention), 40 minutes, and 90 minutes post-capsaicin application.

• Pain-Related Emotional States

  From baseline through 90 minutes post-capsaicin application, assessed every 10 minutes.

• Pain-Related Cognitive States

  At baseline, 40 minutes post-capsaicin, and 90 minutes post-capsaicin.

Study Arms (2)

Active taVNS

ACTIVE COMPARATOR

Device: Transcutaneous Auricular Vagus Nerve Stimulation

Sham taVNS

SHAM COMPARATOR

Device: Transcutaneous Auricular Vagus Nerve Stimulation

Interventions

Transcutaneous Auricular Vagus Nerve Stimulation DEVICE

Participants receive taVNS using a percutaneous electrical stimulation device. The stimulation is delivered to the auricular branch of the vagus nerve via two modified punctate electrodes with the following parameters: frequency = 30 Hz, pulse width = 200 μs, duration = 30 minutes.

Active taVNS

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• \- 1. Adults aged 18 to 65 years. 2. Physically and mentally healthy individuals with no history of chronic pain (confirmed via clinical interviews and the MINI International Neuropsychiatric Interview).
• \. Right-handed.

You may not qualify if:

• \. Presence of metallic implants (e.g., cardiac pacemakers) or other conditions precluding vagus nerve stimulation.
• \. Diagnosis of psychiatric disorders or presence of suicidal ideation. 3. History of epilepsy. 4. History of drug or substance abuse/dependence. 5. Known allergy to capsaicin or its vehicle solutions. 6. Inability to understand or respond to study-related questions.

Sponsors & Collaborators

• Second Affiliated Hospital, School of Medicine, Zhejiang University: lead

MeSH Terms

Conditions

Agnosia

Condition Hierarchy (Ancestors)

Perceptual Disorders; Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Lina Yu, M.D.

CONTACT

8613958033387; zryulina@zju.edu.cn

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Doctor

Study Record Dates

• First Submitted: June 29, 2026
• First Posted: July 22, 2026
• Study Start: July 10, 2026
• Primary Completion (Estimated): July 10, 2027
• Study Completion (Estimated): September 10, 2027
• Last Updated: July 22, 2026

Record last verified: 2026-06