AUTHOR=Beltran Serrano Gerardo , Rodrigues Laura Pooch , Schein Bruno , Souza Andressa , Torres Iraci L. S. , da Conceição Antunes Luciana , Fregni Felipe , Caumo Wolnei 

TITLE=Comparison of Hypnotic Suggestion and Transcranial Direct-Current Stimulation Effects on Pain Perception and the Descending Pain Modulating System: A Crossover Randomized Clinical Trial

JOURNAL=Frontiers in Neuroscience

VOLUME=13

YEAR=2019

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2019.00662

DOI=10.3389/fnins.2019.00662

ISSN=1662-453X

ABSTRACT=<p><bold>Objectives:</bold> This paper aims to determine if hypnotic analgesia suggestion and transcranial direct-current stimulation (tDCS) have a differential effect on pain perception. We hypothesized that transcranial direct-current stimulation would be more effective than hypnotic analgesia suggestion at changing the descending pain modulating system, whereas the hypnotic suggestion would have a greater effect in quantitative sensory testing.</p><p><bold>Design:</bold> This is a randomized, double blind and crossover trial.</p><p><bold>Settings:</bold> All stages of this clinical trial were performed at the Laboratory of Pain and Neuromodulation of the Hospital de Clínicas de Porto Alegre.</p><p><bold>Subjects:</bold> Were included 24 healthy females aged from 18 to 45 years old, with a high susceptibility to hypnosis, according to the Waterloo-Stanford Group Scale of Hypnotic Susceptibility, Form C (15).</p><p><bold>Methods:</bold> The subjects received a random and crossover transcranial direct-current stimulation over the dorsolateral prefrontal cortex (2 mA for 20 min) and hypnotic analgesia (20 min).</p><p><bold>Results:</bold> Only hypnotic suggestion produced changes that are statistically significant from pre- to post-intervention in the following outcomes measures: heat pain threshold, heat pain tolerance, cold pressure test, and serum brain-derivate-neurotrophic-factor. The analysis showed a significant main effect for treatment (<italic>F</italic> = 4.32; <italic>P</italic> = 0.04) when we compared the delta-(Δ) of conditioned pain modulation task between the transcranial direct-current stimulation and hypnotic suggestion groups. Also, the change in the brain-derivate-neurotrophic-factor was positively correlated with the conditioned pain modulation task.</p><p><bold>Conclusion:</bold> The results confirm a differential effect between hypnotic suggestion and transcranial direct-current stimulation on the pain measures. They suggest that the impact of the interventions has differential neural mechanisms, since the hypnotic suggestion improved pain perception, whereas the transcranial direct-current stimulation increased inhibition of the descending pain modulating system.</p><p><bold>Clinical Trial Registration:</bold><ext-link ext-link-type="uri" xlink:href="http://www.ClinicalTrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">www.ClinicalTrials.gov</ext-link>, identifier NCT03744897.</p><p><bold>Perspective:</bold> These findings highlight the effect of hypnotic suggestion on contra-regulating mechanisms involved in pain perception, while the transcranial direct-current stimulation increased inhibition of the descending pain modulating system. They could help clinicians comprehend the mechanisms involved in hypnotic analgesia and transcranial direct-current stimulation and thus may contribute to pain and disability management.</p>