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The effects of transcranial direct current stimulation on metabolite changes at the anterior cingulate cortex in neuropathic pain: a pilot study

Authors Auvichayapat P, Keeratitanont K, Janyachareon T, Auvichayapat N

Received 3 May 2018

Accepted for publication 3 July 2018

Published 11 October 2018 Volume 2018:11 Pages 2301—2309


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr E Alfonso Romero-Sandoval

Paradee Auvichayapat,1 Keattichai Keeratitanont,2 Taweesak Janyachareon,3 Narong Auvichayapat4

1Department of Physiology; 2Department of Radiology; 3Department of Physical Therapy; 4Division of Pediatric Neurology, Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand

Background: Neuropathic pain (NP) in individuals with spinal cord injury (SCI) is both common and highly refractory to treatment. Primary motor cortex stimulation can relieve pain by interrupting the transmission of noxious information of descending pain modulatory systems including the anterior cingulate cortex (ACC). Previous research has shown that transcranial direct current stimulation (tDCS) can produce pain relief in individuals with NP. However, the underlying mechanisms for these effects are not yet understood. Research findings suggest the possibility that changes in brain metabolite concentrations produced by tDCS might explain some of these effects. For example, previous research has shown that SCI-related NP is associated with elevated levels of glutamine combined glutamate (Glx) per creatine (Glx/Cr). In addition, decreased N-acetylaspartate (NAA) has been observed in the ACC in individuals with chronic pain.
Methods: We used magnetic resonance spectroscopy (MRS) to study changes in NAA and Glx levels in the ACC after tDCS treatment. Ten patients with SCI with NP were given five daily anodal tDCS sessions, and an MRS evaluation was performed before and after treatment.
Results: The results showed treatment-related reductions in pain, and increases in both Glx/Cr and NAA/Cr in the ACC. The observed increase in NAA/Cr is consistent with the possibility that tDCS improves the descending pain modulation system by increasing the neuronal activity in the ACC.
Conclusion: The findings suggest the possibility that tDCS’s beneficial effects on neuropathic pain may be due, at least in part, to the changes it produces in Glx/Cr and NAA/Cr levels in the ACC. Additional research with larger samples sizes and a control group to evaluate this possibility is warranted.

Keywords: magnetic resonance spectroscopy, neuropathic pain, spinal cord injury, transcranial direct current stimulation, anterior cingulate cortex

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