Transcranial Direct Current Stimulation as a Therapeutic Tool for Chronic Pain

Abstract

Transcranial direct current stimulation (tDCS) modulates spontaneous neuronal activity that can generate long-term neuroplastic changes. It has been used in numerous therapeutic trials showing significant clinical effects especially when combined with other behavioral therapies. One area of intensive tDCS research is chronic pain. Since the initial tDCS trials for chronic pain treatment using current parameters of stimulation, more than 60 clinical trials have been published testing its effects in different pain syndromes. However, as the field moves in the direction of clinical application, several aspects need to be taken into consideration regarding tDCS effectiveness and parameters of stimulation. In this article, we reviewed the evidence of tDCS effects for the treatment of chronic pain and critically analyzed the literature pertaining its safety and efficacy, and how to optimize tDCS clinical effects in a therapeutic setting. We discuss optimization of tDCS effects in 3 different domains: (i) parameters of stimulation, (ii) combination therapies, and (iii) subject selection. This article aims to provide insights for the development of future tDCS clinical trials.

The Analgesic Effect of Transcranial Direct Current Stimulation (tDCS) combined with Physical Therapy on Common Musculoskeletal Conditions: A Systematic Review and Meta-Analysis

“…Despite the low number of studies, our metaanalysis suggests that the combination of tDCS with PTM does not show to be beneficial in relieving pain for CLBP, but it might for the conditions of fibromyalgia and KOA as compared to PTM alone. tDCS is likely to act on neuronal state to indirectly influence the central sensitization which is thought to be present in chronic MSK conditions (Pinto et al, 2018). Central sensitization levels can vary according to symptom chronicity and the presence of psychosocial factors such as anxiety, depression and catastrophization (Adams & Turk, 2015).…”

“…(Liew et al, 2014) Non-invasive brain stimulation (NIBS) techniques are designed to act on neuronal state via the application of magnetic or electrical field through the skull. These techniques have shown to influence pain perception (Pinto et al, 2018) and motor performances, which may translate to clinical improvements (Jacobson et al, 2012). It has been proposed that these types of stimulations facilitate a change in dysfunctional excitability patterns in the brain, inducing neuronal plasticity (Reis et al, 2009) , (Censor et al, 2010) and are beneficial to minimize pain and improve physical function (Buch et al, 2011) , (Conde et al, 2013).…”

Transcranial electrical and magnetic stimulation (tES and TMS) for addiction medicine: A consensus paper on the present state of the science and the road ahead

“…Reproducibility of the results is paramount and there must be a clear description of the protocol used for the interventions (Brunoni et al, 2012). Montages with anode and cathode positions (including number of respective electrodes) (Nasseri et al, 2015), how this montage was determined (measurements, neuro-navigation), size and shape of electrodes (rectangular, circular or EEG type), current intensity, duration, number of sessions and interval between sessions (Thibaut et al, 2017) are extremely important parameters that need to be made explicit (Pinto et al, 2018). For tACS, a particularly vexing problem for the field has been the confusion between peak-to-peak and true (baseline-topeak) amplitude.…”

Non-invasive neuromodulation effects on painful diabetic peripheral neuropathy: a systematic review and meta-analysis

“…Recently, publications on NINM techniques as a treatment for painful DPN grew. Previous narrative 19,20 and systematic reviews [21][22][23] have addressed the use of NINM techniques as therapeutic option for chronic pain syndromes reporting small to moderate positive effect sizes, however, those studies included some patients with DPN, but failed to study specifically the DPN population; furthermore, they did not compare central versus peripheral techniques or include changes on neurophysiological biomarkers such as nerve conduction studies, which represents axonal and myelin damage and could be use as biomarkers of nerve damage recovery in DPN patients 24 . No systematic reviews summarizing the use of NINM techniques in this condition are reported; hence, the efficacy and safety of these techniques on patients with painful DPN and their effects on neurophysiological biomarkers remain unclear.…”