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The Analgesic Effect of Transcranial Direct Current Stimulation in Fibromyalgia: A Systematic Review, Meta-Analysis, and Meta-Regression of Potential Influencers of Clinical Effect

  • Paulo E.P. Teixeira
    Correspondence
    Address correspondence to: Paulo E.P. Teixeira, Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, 79/96 13th St, 1st Fl, Ste 105, Charlestown, MA 02129, USA.
    Affiliations
    MGH Institute of Health Professions, Boston, MA, USA

    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA
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  • Kevin Pacheco-Barrios
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA

    Universidad San Ignacio de Loyola, Vicerrectorado de Investigación, Unidad de Investigación para la Generación y Síntesis de Evidencias en Salud, Lima, Peru
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  • Luis Castelo Branco
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA
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  • Paulo S. de Melo
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA
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  • Anna Marduy
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA
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  • Wolnei Caumo
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Post-Graduate Program in Medical Sciences, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil

    Laboratory of Pain and Neuromodulation at Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil

    Pain and Palliative Care Service at Hospital de Clínicas de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil

    Department of Surgery, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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  • Stefania Papatheodorou
    Affiliations
    Harvard T. H. Chan School of Public Health, Boston, MA, USA
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  • Julie Keysor
    Affiliations
    MGH Institute of Health Professions, Boston, MA, USA
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  • Felipe Fregni
    Affiliations
    Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital, Massachusetts General Hospital, Charlestown, MA, USA

    Harvard Medical School, Boston, MA, USA

    Harvard T. H. Chan School of Public Health, Boston, MA, USA
    Search for articles by this author
Published:November 23, 2022DOI:https://doi.org/10.1016/j.neurom.2022.10.044

      Abstract

      Background

      There is tentative evidence to support the analgesic effect of transcranial direct current stimulation (tDCS) in fibromyalgia (FM), with large variability in the effect size (ES) encountered in different clinical trials. Understanding the source of the variability and exploring how it relates to the clinical results could characterize effective neuromodulation protocols and ultimately guide care in FM pain. The primary objective of this study was to determine the effect of tDCS in FM pain as compared with sham tDCS. The secondary objective was to explore the relationship of methodology, population, and intervention factors and the analgesic effect of tDCS in FM.

      Materials and Methods

      For the primary objective, a systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Randomized clinical trials (RCTs) investigating tDCS as an intervention for FM pain were searched in MEDLINE, Embase, and the Web Of Science. Studies were excluded if they used cross-over designs or if they did not use tDCS as an intervention for pain or did not measure clinical pain. Analysis for the main outcome was performed using a random-effects model. Risk of bias and evidence certainty were assessed for all studies using Cochrane Risk of Bias and Grading of Recommendations Assessment, Development, and Evaluation tools. For the secondary objective, a meta-regression was conducted to explore methodology, population, and intervention factors potentially related to the ES.

      Results

      Sixteen RCTs were included. Six studies presented a high risk of bias. Significant reduction in pain scores were found for FM (standardized mean difference = 1.22, 95% CI = 0.80−1.65, p < 0.001). Subgroup analysis considering tDCS as a neural target revealed no differences between common neural sites. Meta-regression revealed that the duration of the tDCS protocol in weeks was the only factor associated with the ES, in which protocols that lasted four weeks or longer reported larger ES than shorter protocols.

      Conclusions

      Results suggest an analgesic effect of tDCS in FM. tDCS protocols that last four weeks or more may be associated with larger ESs. Definite conclusions are inadequate given the large heterogeneity and limited quality of evidence of the included studies.

      Keywords

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