The Combined Effect of TENS and TaVNS on Pressure and Heat Pain Thresholds in Pain-Free Subjects

Not Applicable

Completed

• Conditions: Healthy Volunteers
• Interventions: Device: Placebo Transcutaneous Auricular Vagus Nerve Stimulation (TaVNS); Device: Active Transcutaneous Auricular Vagus Nerve Stimulation (TaVNS); Device: Transcutaneous Electrical Nerve Stimulation

• Registration Number: NCT06361381
• Lead Sponsor: University of Hartford

Brief Summary

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive modality that utilizes electrical currents to modulate pain in populations with acute and chronic pain. TENS has been demonstrated to produce hypoalgesic effects in postoperative pain, fibromyalgia, knee osteoarthritis, and healthy subjects. Transcutaneous auricular vagus nerve stimulation (TaVNS) is a non-invasive modality that modulates the vagus nerve by stimulating its auricular branches. The effects of the combination of TENS and TaVNS on producing an analgesic response have not been studied. Considering that TENS and TaVNS both stimulate similar analgesic pathways but through different means of activation, the investigators can hypothesize that a combination of both methods can produce a more pronounced analgesic response. Therefore, the objective of this study is to assess the hypoalgesic effect of a combination of TENS and TaVNS in pain-free subjects.

The study will be a simple crossover design conducted at the University of Hartford. Subjects will be recruited from the University of Hartford population via oral communication, digital flyers, and posters on campus. Thirty participants will undergo two sessions in a crossover manner with one week in between. During one session, the participants will receive TENS with active TaVNS and the other session will be a placebo procedure (TENS with placebo TaVNS). The order of these sessions will be randomized. Importantly, the pressure pain threshold (PPT) and heat pain threshold (HPT) assessors will be blinded to the treatment category. For active TaVNS, a frequency of 25 Hz will be applied with a pulse duration of 200 µs. For placebo TaVNS, the intensity will be increased to a sensory level and then decreased to 0 mA. High frequency TENS of 100Hz will be applied in both sessions, with a pulse duration of 200 µsec, asymmetrical biphasic square waveform, and intensity of maximal tolerance without pain. TENS and TaVNS will be turned on for 30 minutes after a baseline measurement of outcomes. TENS and TaVNS will then be turned off, but the electrodes will remain on until completion of post-treatment assessment. Pressure pain threshold, heat pain threshold, blood pressure, oxygen saturation and heart rate will be tested 4 times: Once pre-intervention, once during intervention, once immediately after the intervention and once 15 minutes post-intervention.

Detailed Description

The study will be a simple crossover design with the following two treatments: (1) active TaVNS and (2) placebo TaVNS. Each subject will receive both interventions in random order.

Pressure and Heat pain thresholds will be recorded at baseline, 15 min, 30 min, and 45 min.

Study Timeline

• Study First Submitted: 2024-03-25
• Study Start: 2024-04-01
• Study First Submitted QC: 2024-04-09
• Study First Posted: 2024-04-11
• Primary Completion: 2024-07-20
• Study Completion: 2024-10-20
• Status Verified: 2024-12
• Last Update Submitted: 2024-12-03
• Last Update Posted: 2024-12-06

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 30

Inclusion Criteria

• Absence of pain
• Age 18-40
• Men and women

Exclusion Criteria

• Neurological diseases
• Severe cardiorespiratory disease
• Pregnancy
• Skin infection or lesions or change in sensation at the TENS or TaVNS application site
• Cancer
• Cardiac pacemaker
• Allergy to electrodes
• Chronic illness or pain
• Use of drugs that affect pain or vagal tone in the past 48 hours prior to data collection

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Placebo TaVNS	Placebo Transcutaneous Auricular Vagus Nerve Stimulation (TaVNS)	Placebo TaVNS: the intensity will be increased to a sensory level and then decreased to 0 mA
Active TaVNS	Active Transcutaneous Auricular Vagus Nerve Stimulation (TaVNS)	Active TaVNS: frequency of 25 Hz, pulse duration of 200 µs, at a strong but comfortable intensity.
Active TaVNS	Transcutaneous Electrical Nerve Stimulation	Active TaVNS: frequency of 25 Hz, pulse duration of 200 µs, at a strong but comfortable intensity.
Placebo TaVNS	Transcutaneous Electrical Nerve Stimulation	Placebo TaVNS: the intensity will be increased to a sensory level and then decreased to 0 mA

Primary Outcome Measures

Name	Time	Method
Pressure Pain Threshold	2 weeks	A digital pressure algometer will measure the pain threshold to deep mechanical stimuli in kPa

Secondary Outcome Measures

Name	Time	Method
Heat Pain Threshold	2 weeks	Superficial heat pain sensitivity, in degree Celsius, will be assessed using a handheld thermode.
Heart rate	2 weeks	Heart rate (beats per minute) will be assessed using a fingertip pulse oximeter
Oxygen saturation	2 weeks	Oxygen saturation in percentage will be assessed using a fingertip pulse oximeter
Blood pressure	2 weeks	Systolic and Diastolic Blood pressure in millimeters of mercury will be assessed using a upper arm cuff, blood pressure monitor

Trial Locations

Locations (1)

University of Hartford; 🇺🇸 West Hartford, Connecticut, United States