Neurophysiological and clinical effects associated to the median nerve stimulation combined with physical exercise on experimental pain in sedentary individuals: a randomized double-blind study

Author(s)

Fabiana Tenório Gomes da Silva

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Psicologia (IP/SBD)
• Defense date: 2020-01-30

Examining board members

Maria Elisa Pimentel Piemonte; Linamara Rizzo Battistella; Marcelo Fernandes da Costa; Paulo Moreira Silva Dantas; Camila Bonin Pinto; Koichi Sameshima

• Advisor: Felipe Fregni; Marcel Simis

Abstract

Physical exercise and Median Nerve Stimulation (MNS) are powerful non-pharmacological tools to control pain. However, the effects of sequential and concurrent (simultaneous) of these two neuromodulatory techniques have not been explored. Both Physical exercise and MNS activate the endogenous pain inhibitory systems, therefore, combining the two treatments could have a synergistic effect and increase their effects on pain control. Therefore the main of this study is analyze whether the MNS using a novel algorithm that varies intensity and frequency of stimulation ((intensity (2 mA and 4-6 mA) and frequency (1-4 Hz, 8-12 Hz and 60-90 Hz)) plus physical exercise will reduce pain sensation and increase Pain Pressure Test (PPT) and Conditioned pain modulation (CPM) as compared with physical exercise alone and physical exercise plus placebo MNS. As a secondary objective will be analyzed the time to reach physical exhaustion and the perception of exertion during physical exercise and make an exploratory analysis of cerebral cortical activity, measured by electroencephalograph during ENM. Twenty-four healthy right-hand dominant adults (12 women; 25 mean age ±5.53 years) participated in this double-blinded, randomized, cross-over trial. Each subject underwent a control (i.e., no intervention), sham and active MNS. MNS was applied for 20 minutes at rest and then for 10minutes during the warm-up period on the treadmill. Pain tests (PPT, CPM and pain sensation (VAS)) were performed at three time-points; at baseline (T0), after the 20 minutes of stimulation (T1) and after the physical exercise session (T2). In addition, during physical exercise, the perceived exertion and pain sensation were assessed. We found a significant difference in the variation (T1 minus T2) of left PPT between the active and sham groups (p=0.039) and between the active and control groups (p=0.041), such as that pain thresholds at the left side were higher only in the active group. Regarding VAS during physical exercise we found a significant difference between the active and control groups at 40% of maximal time of exercise (p=0.036), such as that the active group had less pain compared to the control group. Regarding qEEG analysis during the MNS, to the power the active MNS had significant differences in the delta for central (p<0.05) region toward reduction and in the high beta for frontal right, frontal left, central right, central left, frontal central and central regions (p <0.05) toward increase when compared with control. Sham MNS had significant differences in the delta for central (p <0.05) region toward reduction and in the high beta for frontal left, central right, central left, frontal central and central regions (p <0.05) toward increase when compared with control. To coherence active MNS induced a significant increase in alpha (p<0.05) as compared with the sham stimulation for the pair of electrodes C3-C4 and sham MNS induced a significant reduction in alpha (p<0.05) as compared with the control condition in the same pair of electrodes. Our findings suggest a effect of a single session of MNS on pain levels during and after physical exercise and modulation in cortical activity indexed by power and coherence. This study investigates a novel approach to analyze the sequential and concurrent effect of two neuromodulatory techniques that modulate the pain. Thus, this study provides insights for future studies testing this combined approach (AU)

• FAPESP's process: 16/06459-3 - THE EFFECTS OF SENSORY TRAINING ON PAIN MODULATION, COGNITION AND TIME TO FATIGUE IN HEALTHY ADULTS.
• Grantee: Fabiana Tenório Gomes da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate