Effect of Hypnosis Combined With Tdcs on Pain Perception and Cortical Excitability in Fibromyalgia

Fibromyalgia is a public health condition, which causes great functional disability. Its consequences pervade the personal and social life of the patient, leading to significant impairments in their interpersonal relationships, including work, family and social spheres. The symptoms affect both the physical and emotional abilities. Conventional treatment modalities have been shown a very poor therapeutic response, in that most individuals end up becoming poly-medicated and refractory to treatment. Non-pharmacological techniques with promising effects on the syndrome symptoms include both hypnotic analgesia and the transcranial direct-current stimulation (tDCS). Giving the treatment limitations of this syndrome its important to better understand the pain processess in fibromyalgia and treatments effect. This project was developed in order to evaluate the synergistic effect of a hypnotic analgesia suggestion associated with tDCS over pain levels and cortical excitability in individuals with fibromyalgia over a nociceptive stimulation pattern. It will be performed as a blinded sham controlled cross-over randomized clinical trial. It will be included 20 female subjects diagnosed with fibromyalgia, according to the 2016 revision of the American College of Rheumatologycriteria (2010;2011), ranging in age from 18 to 65 years old, highly susceptible to the hypnosis technique (score ≥ 8) according to the Waterloo-Stanford Scale of Hypnotic Susceptibility (WSGC). They will be allocated in one of two groups, receiving with each cross-over one of the following interventions: A (active-tDCS), B (hypnotic analgesia suggestion), C (Rest), D (active-tDCS + hypnotic analgesia suggestion) and E (sham-tDCS + hypnotic analgesia suggestion). The primary endpoints will be the level of pain, measured by a numerical pain scale (NPS), during nociceptive stimuli induced by the cold pressor test and Short Intracortical Inhibition (SICI). The secondary endpoints will be descent pain modulation system power through the Conditioned Pain Modulation test (CPM - task); and the cortical excitability assessed by Motor Threshold (MT), Motor Evoked Potential (MEP), Cortical Silent Period (CSP) and Short Intracortical Facilitation (SICF) tests during Transcranial Magnetic Stimulation (TMS). The intra and inter-group comparisons will be made by means of two-way ANOVA followed by Bonferroni. A type I error of 5% and type II error of 20%. The present study hypothesizes a synergistic effect of both interventions on pain intensity reported on the Cold Pressor Test, as well as the reduction in the inhibition of cortical excitability level assessed by the TMS, compared to the same measures in an isolated manner.