The effects of transcranial direct current stimulation with visual illusion in neuropathic pain due to spinal cord injury: An evoked potentials and quantitative thermal testing study

Authors

  • H. Kumru,

    Corresponding author
    • Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
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    • These two authors participated equally in the study.
  • D. Soler,

    1. Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
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    • These two authors participated equally in the study.
  • J. Vidal,

    1. Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
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  • X. Navarro,

    1. Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
    2. Institute of Neurosciences, Universitat Autònoma de Barcelona, and CIBERNED, Bellaterra, Spain
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  • J.M. Tormos,

    1. Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
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  • A. Pascual-Leone,

    1. Institut Guttmann, Hospital de Neurorehabilitació, Institut Universitari adscript a la Universitat Autonoma de Barcelona, Barcelona, Spain
    2. Berenson-Allen Center for Nonininvasive Brain Stimulation, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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  • J. Valls-Sole

    1. Hospital Clinic, Barcelona, Spain
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  • Funding sources

    This work was supported in part by grants from the Foundation La Marató TV3 (110930 and 110932) and (grants 071930, 071931 and 070210) and grants (PI082004 and PI10/00442) from the Instituto de Salud Carlos III and grants from the Cátedra BBVA (CAT06/023).

  • Conflicts of interest

    The authors do not have any conflicts of interest.

Correspondence

Hatice Kumru

E-mail: hkumru@guttmann.com

Abstract

Background

Neuropathic pain (NP) is common in spinal cord injury (SCI) patients. One of its manifestations is a lowering of pain perception threshold in quantitative thermal testing (QTT) in dermatomes rostral to the injury level. Transcranial direct current stimulation (tDCS) combined with visual illusion (VI) improves pain in SCI patients. We studied whether pain relief with tDCS + VI intervention is accompanied by a change in contact heat- evoked potentials (CHEPs) or in QTT.

Methods

We examined 18 patients with SCI and NP before and after 2 weeks of daily tDCS + VI intervention. Twenty SCI patients without NP and 14 healthy subjects served as controls. We assessed NP intensity using a numerical rating scale (NRS) and determined heat and pain thresholds with thermal probes. CHEPs were recorded to stimuli applied at C4 level, and subjects rated their perception of evoked pain using NRS during CHEPs.

Results

Thirteen patients reported a mean decrease of 50% in the NRS for NP after tDCS + VI. Evoked pain perception was significantly higher than in the other two groups, and reduced significantly together with CHEPs amplitude after tDCS + VI with respect to baseline. Pain perception threshold was significantly lower than in the other two groups before tDCS + VI intervention, and increased significantly afterwards.

Conclusion

Two weeks of tDCS + VI induced significant changes in CHEPs, evoked pain and heat pain threshold in SCI patients with NP. These neurophysiological tests might be objective biomarkers of treatment effects for NP in patients with SCI.

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