Niran Ngernyam1, Mark P Jensen2, Preeda Arayawichanon3, Narong Auvichayapat4, Somsak Tiamkao5, Suparerk Janjarasjitt6, Wiyada Punjaruk1, Anuwat Amatachaya1, Benchaporn Aree-uea1, Paradee Auvichayapat7. 1. Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. 2. Department of Rehabilitation Medicine, University of Washington, Seattle, USA. 3. Department of Rehabilitation Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. 4. Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. 5. Department of Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. 6. Department of Electrical and Electronic Engineering, Faculty of Engineering, UbonRatchathani University, UbonRatchathani, 34190 Thailand. 7. Department of Physiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002 Thailand. Electronic address: aparad@kku.ac.th.
Abstract
OBJECTIVE:Transcranial direct current stimulation (tDCS) has demonstrated efficacy for reducing neuropathic pain, but the respective mechanisms remain largely unknown. The current study tested the hypothesis that pain reduction with tDCS is associated with an increase in the peak frequency spectrum density in the theta-alpha range. METHODS:Twenty patients with spinal cord injury and bilateral neuropathic pain receivedsingle sessions of both sham and anodal tDCS (2 mA) over the left primary motor area (M1) for 20 min. Treatment order was randomly assigned. Pre- to post-procedure changes in pain intensity and peak frequency of electroencephalogram spectral analysis were compared between treatment conditions. RESULTS: The active treatment condition (anodal tDCS over M1) but not sham treatment resulted in significant decreases in pain intensity. In addition, consistent with the study hypothesis, peak theta-alpha frequency (PTAF) assessed from an electrode placed over the site of stimulation increased more from pre- to post-session among participants in the active tDCS condition, relative to those in the sham tDCS condition. Moreover, we found a significant association between a decrease in pain intensity and an increase in PTAF at the stimulation site. CONCLUSIONS: The findings are consistent with the possibility that anodal tDCS over the left M1 may be effective, at least in part, because it results in an increase in M1 cortical excitability, perhaps due to a pain inhibitory effect of motor cortex stimulation that may influence the descending pain modulation system. Future research is needed to determine if there is a causal association between increased left anterior activity and pain reduction. SIGNIFICANCE: The results provide new findings regarding the effects of tDCS on neuropathic pain and brain oscillation changes.
RCT Entities:
OBJECTIVE: Transcranial direct current stimulation (tDCS) has demonstrated efficacy for reducing neuropathic pain, but the respective mechanisms remain largely unknown. The current study tested the hypothesis that pain reduction with tDCS is associated with an increase in the peak frequency spectrum density in the theta-alpha range. METHODS: Twenty patients with spinal cord injury and bilateral neuropathic pain received single sessions of both sham and anodal tDCS (2 mA) over the left primary motor area (M1) for 20 min. Treatment order was randomly assigned. Pre- to post-procedure changes in pain intensity and peak frequency of electroencephalogram spectral analysis were compared between treatment conditions. RESULTS: The active treatment condition (anodal tDCS over M1) but not sham treatment resulted in significant decreases in pain intensity. In addition, consistent with the study hypothesis, peak theta-alpha frequency (PTAF) assessed from an electrode placed over the site of stimulation increased more from pre- to post-session among participants in the active tDCS condition, relative to those in the sham tDCS condition. Moreover, we found a significant association between a decrease in pain intensity and an increase in PTAF at the stimulation site. CONCLUSIONS: The findings are consistent with the possibility that anodal tDCS over the left M1 may be effective, at least in part, because it results in an increase in M1 cortical excitability, perhaps due to a pain inhibitory effect of motor cortex stimulation that may influence the descending pain modulation system. Future research is needed to determine if there is a causal association between increased left anterior activity and pain reduction. SIGNIFICANCE: The results provide new findings regarding the effects of tDCS on neuropathic pain and brain oscillation changes.
Authors: Kelsey A Potter-Baker; Daniel P Janini; Yin-Liang Lin; Vishwanath Sankarasubramanian; David A Cunningham; Nicole M Varnerin; Patrick Chabra; Kevin L Kilgore; Mary Ann Richmond; Frederick S Frost; Ela B Plow Journal: J Spinal Cord Med Date: 2017-08-07 Impact factor: 1.985