Transauricular Vagal Nerve Stimulation, Pressure Pain and Interoception
- Conditions
- Pain, Acute
- Interventions
- Device: Earlobe StimulationDevice: taVNS
- Registration Number
- NCT06240026
- Lead Sponsor
- Aalborg University
- Brief Summary
The study is exploring whether, and for how long, taVNS may modulate deep muscular pressure pain thresholds, heartbeat, and thermal perception (Ethics Region Nord Jylland Denmark, N-20230022). To achieve this, 30 healthy subjects will complete a randomized, active control, crossover study. The main intervention is left concha taVNS (NEMOS, CerboMed GmbH, Erlangen, Germany) for 20 minutes (200µs duration, 25Hz, at a personalized intensity). This will be compared to an active control of identical electrical stimulation to the left earlobe. A blinding assessment inquiring which stimulation is supposed to be therapeutic will be collected. Main outcomes are pressure pain thresholds and temporal summation of pain responses acquired via cuff-pressure algometer (Cortex Technology, Aalborg University, Denmark) placed at the calf. Heartbeat perception, assessed via the heartbeat counting task, and thermal perception, assessed using a QST thermal grid, are also primary outcomes. Secondary outcomes are conditioned pain modulation, resting state electroencephalography, electrocardiography, and pupillary light reflexes.
- Detailed Description
Interoception, the ability to perceive, process and respond to signals originating from within the body, is crucial for maintaining healthy physiological ranges. Indeed, dysfunction in this ability has been associated with various mood and pain disorders. Based on the overlap between the anatomical pathway of this ability and the site of action of the tool, transauricular vagal nerve stimulation (taVNS) could modulate this interoception. However, little is known about the breadth, duration, and mechanism of interoception modulation by taVNS.
The current study will address these limitations, with a focus on three interoceptive channels: deep muscular pressure pain, heartbeat, and thermal perception. Specifically, 30 healthy subjects will complete a randomized, active control, crossover study containing two stimulation sessions.
The main intervention is left concha taVNS (NEMOS, CerboMed GmbH, Erlangen, Germany) for 20 minutes (200µs duration, 25Hz, at a personalized intensity). The active control will be identical electrical stimulation to the left earlobe. To assess blinding, a questionnaire inquiring which stimulation is supposed to be therapeutic will be collected at the end of the study.
Main outcomes are pressure pain thresholds and temporal summation of pain responses acquired via cuff-pressure algometer (Cortex Technology, Aalborg University, Denmark) placed at the calf. Heartbeat perception, assessed via the heartbeat counting task, and thermal perception, assessed using a QST thermal grid, are also primary outcomes. Secondary outcomes are conditioned pain modulation, resting state electroencephalography, electrocardiography, and pupillary light reflexes.
To assess whether, and how, taVNS modulates deep muscular pressure pain, heartbeat, and thermal perception, primary and secondary measurements pre, post and 30min post stimulation will be collected and compared. To assess the duration of the potential effects, these outcomes will be collected, and compared, at 5min intervals until the primary measurements are within 20% of baseline values. Given baseline is recovered, the second stimulation session will take place. Given this has not occurred within 1.5h of the cessation of the stimulation in the first stimulation session, subjects will be asked to come back at their earliest convenience.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 30
- Are aged 18-60
- Are healthy
- Speak and understand English
- Are pregnant and/or breastfeeding
- Regularly use cannabis, opioids, or other drugs
- Currently or previously suffered of a neurologic, musculoskeletal, mental, or other illnesses (e.g., brain or spinal cord injuries, degenerative neurological disorders, major depression, cardiovascular disease, chronic lung disease, etc.)
- Once or more a week take of analgesic medication or other medication which may affect the trial (including paracetamol and NSAIDs)
- Have a recent history of acute pain, particularly in the lower limbs.
- Have abnormally disrupted sleep in 24 hours preceding experiment.
- Have contraindications to electric application (history of epilepsy, metal implants in head or jaw, etc.)
- Lack the ability to cooperate.
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description Earlobe Stimulation Earlobe Stimulation A 0.5cm and a 1cm diameter round electrode (Ambu, Neuroline, Bordeaux, France) will respectively be placed on the front and back of the earlobe. When appropriate, these electrodes will be plugged into a digitimer . Whilst pulse width, frequency, stimulation burst and total duration will be respectively standardized to 200microseconds, 20Hz, 30seconds on and 30seconds off and 20minutes, the stimulation will be person specific. To acquire this intensity, participants will perform a thresholding protocol. Based on an elegant stair-case algorithm, the perception and pain (described as a 7/10 pain level, where 10 is the most amount of pain imaginable) thresholds will be obtained. Stimulation intensity will then be defined as 2/3 the range between these thresholds. For example, if the perception and pain thresholds are respectively at 2mA and 8mA, the stimulation intensity would be 6mA. transauricular Vagal Nerve Stimulation taVNS NEMOS taVNS electrodes will be placed in the left concha cymba of participants (CerboMed GmbH, Erlangen, Germany). When appropriate, these electrodes will be plugged into a digitimer. Whilst pulse width, frequency, stimulation burst and total duration will be respectively standardized to 200microseconds, 20Hz, 30seconds on and 30seconds off and 20minutes, the stimulation will be person specific. To acquire this intensity, participants will perform a thresholding protocol. Based on an elegant stair-case algorithm, the perception and pain (described as a 7/10 pain level, where 10 is the most amount of pain imaginable) thresholds will be obtained. Stimulation intensity will then be defined as 2/3 the range between these thresholds. For example, if the perception and pain thresholds are respectively at 2mA and 8mA, the stimulation intensity would be 6mA.
- Primary Outcome Measures
Name Time Method Pain Perception Threshold This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. It will also be taken in 5min intervals post-intervention until the PPT is back within 20% of the pre-intervention value. Pressure algometer cuffs, placed on the calf of participants, attached to an electronic visual analogue scale (VAS) measuring device will be employed. Per cuff, as it inflates, participants are asked to move the dial of the VAS when the pressure begins to be painful. The pressure at which this occurs is referred to as the pain perception threshold (PPT).
Pain Tolerance Threshold This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. Pressure algometer cuffs, placed on the calf of participants, attached to a visual analogue scale (VAS) will be employed. Per cuff, as it inflates, participants are asked to move the dial of the VAS when the pressure begins to be painful. They are then tasked to accordingly move the dial as the pain increases. Importantly, when the pain becomes intolerable, participants are tasked to press the red button which releases all pressure. The pressure at which this occurs is referred to as the pain tolerance threshold (PTT).
Temporary Summation of Pain This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. The pressure algometer cuff will inflate on the dominant leg for 1second, with a 1second break, to the given PTT 10 times consecutively. Participants are asked to move the VAS dial to the pain level at each inflation, without returning to 0 on the scale. Nothing will be done with the cuff on the opposite leg.
Heartbeat Perception This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. Randomly interleaved and without manual help, subjects will be tasked to count their own heartbeat across 3 time-intervals (25, 35 and 45 seconds). The difference between the perceived and actual heartbeat count is defined herein as the heartbeat perception.
Thermal Perception This measurement will be acquired pre-intervention, and directly post- and 30min post-intervention. The QST.lab thermal stimulator contains 6 stimulation regions, which can individually be programmed. First, with all regions programmed identically, participants will be tasked to state when the stimulus is perceived as painfully cold and warm. These will respectively be the cold and warm thresholds. A thermal-grid illusion pattern will then be generated: this involves interleaving stimulation regions as cold (2deg above the cold threshold) and hot (2deg below the hot threshold). Participants will then be asked to rate the pain intensity of this stimulation (0=no pain, 10=worst pain imaginable).
- Secondary Outcome Measures
Name Time Method Handheld Pain Perception Threshold This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. For each side separately, a handheld pressure algometer will be applied at a constant rate of 30kPa/s, perpendicularly to the belly of the musculus trapezius. Participants will be instructed to press a button when they first perceive the pressure to be painful. This is referred to as the handheld pain perception threshold.
Conditioned Pain Modulation This measurement will be taken pre-intervention, and directly post- and 30min post-intervention. The non-dominant leg will receive a continuous pressure of 70% of the PTT previously registered. The cuff on the dominant leg will gradually inflate. As this occurs, participants are once again asked to start moving the dial when the pressure begins to be painful, and to press the red button when this becomes intolerable.
Trial Locations
- Locations (1)
Center for Neuroplasticity and Pain
🇩🇰Gistrup, Region Nordjylland, Denmark