Effect of Transcranial Magnetic Stimulation in the Cortical, Subcortical Neuromodulation and in Pain Threshold of Chronic Myofascial Pain Patients

About 30% of the world population suffers from pain. These data demonstrate the great need for research focusing on findings that contribute to the development of more effectivetreatments for patients with chronic pain syndromesThe chronic pain can occur by various means, either physical or psychological injuries. Above all, whatever its history, its installation is due to mechanisms of neuroplasticity, in this case non-functional, called maladaptive plasticity. This process and the symptoms associated with chronic pain cause the treatment to be a challenge for health professionals. To obtain a positive result, it is necessary to modulate all aspects involved in the processing of pain, including functional retraining.

This study is a randomized, blinded, parallel medical trial, placebo-sham- controlled and will be carried out int the Clinical Research Outpatient Clinic of the Hospital de Clínicas de Porto Alegre (HCPA), with females, aged 19 to 65 years, who are limited in their ability to perform active and routine activities due to MPS in the previous 3 months. We will test the hypothesis that repetitive transcranial magnetic stimulation (rTMS) would be more effective than a placebo-sham for the treatment of chronic MPS by pain score, cortical excitability parameters, function of cortical-spinal modulatory system (CSMS), sleep quality and serum BDNF.The participants will be randomized into the placebo-sham or rTMS treatment groups for 10 consecutive sessions, at 10 Hz frequency. To assessment will be used the visual analogue scale (VAS), Brazilian Profile of Chronic Pain: Screen (B-PCP:S), quantitative sensory testing (QST), TMS parameters, (motor-evoked potential (MEP), intracortical facilitation (ICF) ) and serum BDNF.

Through, these data will prompt us to investigate whether rTMS can be used as a therapeutic option in short and long term in MPS. In this context, we will test the hypothesis that rTMS would be more effective than a placebo-sham for the treatment of chronic MPS that determined some disability. We also will teste whether rTMS would change induced changes in both electrophysiological markers of LTP-like phenomena and in the levels of BDNF. Additionally, we will assess whether the treatment induce changes on the cortical-spinal modulatory system, as well if this effect would be associated with the inhibition or facilitation. Finally, we will test whether rTMS would be more effective than a placebo-sham in improving sleep quality.