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Effects of specific hypnotic suggestions on mechanical and thermal sensitivity of healthy volunteers: randomized and double-blind study

ABSTRACT

BACKGROUND AND OBJECTIVES:

Hypnotic suggestions for hypoalgesia or analgesia are efficient for relieving different pain conditions, presenting few or no side effects. However, little is known about its direct effect on the modulation of peripheral nociception. The goal of this study was to evaluate the mechanical and thermal response after specific hypnotic suggestions in healthy volunteers.

METHODS:

This is a randomized double-blinded controlled trial that aimed to evaluate both mechanical and thermal nociception after specific hypnotic suggestions in healthy volunteers. For this, twenty-seven participants were enrolled, according to the following eligibility criteria: age between 18-65 years and absence of pain complaints or psychological disorders. After signed Free Informed Consent Term (FICT) the participants were divided by a computer-generated randomization in three groups: sham group (no induction of hypnosis), hypnosis-induced pain group and hypnosis-induced analgesia group. Susceptibility to hypnosis was assessed through the Waterloo-Stanford Group C (WSGC) scale of hypnotic susceptibility and outcomes included evaluation of questionnaires (Hospital Anxiety and Depression Scale and Short Form Brief Pain Inventory) as well as the examination of mechanical and thermal nociception through the Quantitative Sensory Testing (QST), a tool widely used to investigate somatosensory sensitivity by assessing functions of small A-δ and C nerve sensory fibers, before and after specific hypnotic suggestion for pain and analgesia made by a qualified hypnotherapist.

RESULTS:

Data demonstrated that specific hypnotic suggestions induced significant changes in mechanical and thermal sensitivity. The pain group revealed an increase in mechanical hyperalgesia and allodynia, while the analgesia group increased pain thresholds to thermal stimulations, being conditioned to withstand temperature changes after hypnosis, demonstrating a modulatory effect for both pain and analgesia sensations in healthy volunteers.

CONCLUSION:

The evidence presented in this study supports the use of the hypnosis technique as an auxiliary tool in clinical practice.

HIGHLIGHTS

  • Specific hypnotic suggestions can modulate peripheral nociception in healthy subjects.

  • Data show a modulatory effect for both pain and analgesia sensations.

  • Hypnosis can be considered a feasible technique for the clinical pain management.

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