Decoding Mechanisms of Pain Modulation (HypnoPain)

University of Oslo

Status: Completed

Conditions: Pain, Acute

Treatments: Device: Sham control; Behavioral: Hypnosis; Device: Vagus nerve stimulation

Study type: Interventional

Funder types: Other

Identifiers

NCT05336370

409472

Details and patient eligibility

About

The main objective of this experimental trial is to gain further insights into the mechanisms of pain modulation, and more specifically, whether expectations of coping is one of the involved mechanisms. This will be investigated by comparing two different interventions known to influence pain perception; hypnosis and non-invasive stimulation of the vagus nerve, prior to a pain exposure task (hand immersion in cold water). Expectations will be assessed both pre- and post intervention.

Full description

Pain is a subjective experience, influenced by biological, psychological and social factors. This multidimensional view of pain has led to various efforts to affect people's pain experience. Nonpharmacological interventions, such as hypnosis, have proven successful in reducing pain whilst providing few, if any, negative side effects. Hypnosis involves a state of highly focused attention, with a constriction in peripheral awareness and a heightened responsiveness to social cues. This particular state can exert a powerful influence on the mind and body, yet the mechanisms responsible for this effect remains to a large degree unknown. The aim of this study is to investigate the effect of hypnosis given prior to a painful procedure (cold pressor test, CPT), to investigate the effect on pain perception and tolerance, but most importantly, to investigate if the effect is mediated by a change in expectations of coping. Previous studies have provided support for the the effect of hypnosis on expectations, but they have focused exclusively on stimulus expectancies (expectations of pain intensity), while the current study will focus on response outcome expectancies (expectations of coping) in line with the Cognitive Activation Theory of Stress (CATS).

Whilst hypnosis may dampen the stress response through expectancies (top-down), another way of dampening the stress response is through transcutaneous vagus nerve stimulation (tVNS) (bottom-up). Vagus nerve stimulation is proposed as another nonopioid pain treatment with minimal side effects. The vagus nerve is the 10th cranial nerve, connecting the viscera and the brain and influencing multiple systems of the body including the cardiac, immunologic, and endocrine system, and the activity of many visceral organs. This makes the vagus nerve a possibly important mediating (transmitting) and modulating nerve of pain signals . Stimulation of the vagus nerve is believed to modulate pain by inhibiting inflammation, oxidative stress, and sympathetic activity, and possibly also by inducing a brain activation pattern that may be incongruent with the pain matrix (i.e. brain regions commonly active during pain). VNS might also mediate the effects of the opioid system in pain modulation. These mechanisms have in common that they are hypothesized to affect neuronal hyperexcitability, resulting in a reduced pain perception, which is supported by experimental animal studies.

Enrollment: 156 patients

Sex: All

Ages: 18 to 70 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Adults aged 18-70 years
• Fluent Norwegian language skills

Exclusion criteria

• History of cardiovascular disease
• Chronic pain conditions (any diagnoses resulting in chronic pain)

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

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156 participants in 3 patient groups

Hypnosis

Experimental group

Description:

A brief hypnosis session will be provided to participants in this arm prior to immersion in the cold water.

Treatment:

Behavioral: Hypnosis

Active tVNS

Experimental group

Description:

Participants in the active tVNS condition will receive electronic stimulation of the vagus nerve prior to immersion in the cold water.

Treatment:

Device: Vagus nerve stimulation

Sham tVNS

Sham Comparator group

Description:

Participants in the sham tVNS will receive the electrode similar to the active treatment, but no stimulation will be performed.

Treatment:

Device: Sham control