TaVNS for Capsaicin-Induced Pain
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Transcutaneous Auricular Vagus Nerve Stimulation, Transcutaneous Auricular Vagus Nerve Stimulation.
- Who it may be relevant to
- Registry conditions: Pain Management, Capsaicin-Induced Pain, Transcranial Magnetic Stimulation Repetitive, Electroencephalography. Basic parameters: 18 years — 65 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Center list to be confirmed — check the primary protocol.
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Official title
Analgesic Efficacy and Neural Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation in a Capsaicin-Induced Pain Model
Overview
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.
Interventions
- Device Transcutaneous Auricular Vagus Nerve Stimulation
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. - Device Transcutaneous Auricular Vagus Nerve Stimulation
Participants receive sham stimulation via the same device, with parameters set to 0.1 Hz for 30 minutes, designed to provide minimal sensory input that is indistinguishable from the active stimulation to ensure double-blinding.
Primary outcome measures
- Pain Intensity [Time frame: Baseline and every 10 minutes up to 90 minutes post-capsaicin application.]
Secondary outcome measures (4)
- Neural Plasticity and Brain Activity [Time frame: Baseline (pre-intervention), 40 minutes, and 90 minutes post-capsaicin application.]
- Brain Network Connectivity [Time frame: Baseline (pre-intervention), 40 minutes, and 90 minutes post-capsaicin application.]
- Pain-Related Emotional States [Time frame: From baseline through 90 minutes post-capsaicin application, assessed every 10 minutes.]
- Pain-Related Cognitive States [Time frame: At baseline, 40 minutes post-capsaicin, and 90 minutes post-capsaicin.]
Eligibility criteria
Inclusion criteria
\- 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).
3\. Right-handed.
Exclusion criteria
- 1\. Presence of metallic implants (e.g., cardiac pacemakers) or other conditions precluding vagus nerve stimulation.
2\. 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.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Single blind
- Primary purpose
- Treatment
Study locations
Center list to be confirmed — check the primary protocol.
Identifiers
NCT: NCT07719868 · 2025-1505