Autonomic Nervous System Modulation, Central Sensitization, Pain Perception, Pain Sensitivity, Vagus Nerve Stimulations
Conditions
Brief summary
In this study, we want to investigate how pain processing and sensation are related to a certain part of the nervous system, the so-called autonomic nervous system. For this purpose, we apply heat and pressure stimuli to the skin and test pain processing by means of ratings scales and sensory tests. Breathing, heart rate and sweat response are also measured. To assess the spinal cord level, we measure muscle response (measured by electromyography, EMG) to electrical stimulation. Additionally, sensory nerves will be stimulated at the ear and participants will also be given various questionnaires to complete.
Detailed description
This study investigates the effects of autonomic regulation on pain perception and experimentally induced pain sensitivity. Participants come for one or two study visits, that will last approximately 3 hours. The study is divided into two phases: the pilot phase and the main experimental phase. During the pilot phase, the perception of pressure and heat stimuli, as well as spinal excitability, will be assessed before and during different types of electrical stimulation of sensory nerves at the outer ear. During the main experimental phase, skin sensitivity and spinal excitability will be assessed before and after repetitive heat stimulation and stimulation of sensory nerves at the outer ear. In both study phases, the activity of the autonomic nervous system will be assessed throughout the experiment, and questionnaires will be completed.
Interventions
OTHERrespiratory gated taVNS
Electrical stimulation will be delivered in bursts during expiration
OTHERrandom burst stimulation
Electrical stimulation will be delivered in bursts at random timepoints during the breathing cycle
OTHERcontinuous stimulation
Electrical stimulation will be delivered continuously for 30sec followed by a 30sec break.
OTHERSham stimulation
Electrical stimulation will be identical to the taVNS, but the electrodes will be placed at a different position on the ear
Sponsors
Schweinhardt Petra
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Intervention model description
This study will be conducted in two phases, a pilot phase and a main experimental phase. The two phases involve different outcome measures. Both phases follow a double-blinded, randomized, within-subject design.
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
1. Over 18 and below 40 years of age 2. Good general health 3. Able to give informed consent
Exclusion criteria
1. Any major medical or psychiatric condition (e.g. heart disease, diabetes, autoimmune disorders, infectious diseases, major depressive disorder), any chronic pain condition, any respiratory problems, any acute pain at time of study 2. Inability to follow study instructions, e.g. due to language problems 3. Pregnancy (female participants will be asked if pregnancy could be possible) 4. Increased alcohol (>2 (for women)/4 (for men) standard glasses per day or >5 (for women)/4 (for men) glasses at least once a month within a few hours) or caffeine consumption (≥ 400mg per day) 5. Consumption of alcohol, drugs, analgesics within the last 24 h 6. Consumption of more than 100 mg of caffeine within the last 8 h 7. Scar tissue or generally reduced sensitivity in the designated testing site areas 8. Shoe size < 38 (if experiment is conducted at the feet) 9. History of cardiovascular disease or carotid artery disease 10. Medication or Substances inferring with the autonomic nervous system or with pain sensitivity (e.g. Benzodiazepines, Nicotine)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Magnitude of the Nociceptive Withdrawl Reflex | Before, during, and/or immediately after the intervention | Muscle responses of the biceps fermoris to an electrical stimulation of the sural nerve will be measured using an electromyogramm |
Other
| Measure | Time frame | Description |
|---|---|---|
| Area of Secondary Hyperalgesia | Before and 20 min after the intervention | Von Frey filaments will be used to assess the spatial extent of experimentally induced hyperalgesia |
| Changes of Pressure Pain Threshold | Before, during, and/or immediately after the intervention | Pressure will be applied over the thenar eminance of the hand until the participant reports a painful sensation |
| Perceived Pain Intensity and Unpleasantness | Before, during, and/or immediately after the intervention | Perceived intensity and unpleasantness of heat stimuli will be assessed using rating scales. The intensity rating scale ranges from 0, indicating no perception, to 100, indicating the pain threshold, and up to 200, indicating the most tolerable pain. The unpleasantness rating scale ranges from -100 for 'extremely unpleasant,' through 0 for 'neutral,' to 100 for 'extremely pleasant. |
| Change in Autonomic Nervous System Activity | Before, during, and up to 2 min after the intervention. | The activity of the autonomic nervous system will be measures using electrocardiogramm and galvanic skin response |
Countries
Switzerland
Contacts
Primary ContactPetra Schweinhardt, PhD, M Chiro Med
Backup ContactMadeleine Hau
Outcome results
None listed