Neuromodulation Techniques in Phantom Limb Pain: A Systematic Review and Meta-analysis

• Published in: Pain medicine (Malden, Mass.) Mass.), 2020-10, Vol.21 (10), p.2310-2322
• Main Authors: Pacheco-Barrios, Kevin, Meng, Xianguo, Fregni, Felipe
• Format: Article
• Language: English
• Subjects: Adult; Care and treatment; Chronic pain; Cortex (motor); Deep brain stimulation; Editor's Choice; Evaluation; Humans; Meta-analysis; Methods; Motor Cortex; Neural stimulation; Neuromodulation; Neuromodulation & Interventional Section; Pain; Pain Measurement; Phantom limb; Phantom Limb - therapy; Systematic review; Testing; Therapeutics, Experimental; Transcranial Direct Current Stimulation; Transcranial Magnetic Stimulation
• ISSN: 1526-2375; 1526-4637
• DOI: 10.1093/pm/pnaa039

Abstract Objective To evaluate the effects of neuromodulation techniques in adults with phantom limb pain (PLP). Methods A systematic search was performed, comprising randomized controlled trials (RCTs) and quasi-experimental (QE) studies that were published from database inception to February 2019 and that measured the effects of neuromodulation in adults with PLP. Hedge’s g effect size (ES) and 95% confidence intervals were calculated, and random-effects meta-analyses were performed. Results Fourteen studies (nine RCTs and five QE noncontrolled studies) were included. The meta-analysis of RCTs showed significant effects for i) excitatory primary motor cortex (M1) stimulation in reducing pain after stimulation (ES = −1.36, 95% confidence interval [CI] = −2.26 to −0.45); ii) anodal M1 transcranial direct current stimulation (tDCS) in lowering pain after stimulation (ES = −1.50, 95% CI = −2.05 to 0.95), and one-week follow-up (ES = −1.04, 95% CI = −1.64 to 0.45). The meta-analysis of noncontrolled QE studies demonstrated a high rate of pain reduction after stimulation with transcutaneous electrical nerve stimulation (rate = 67%, 95% CI = 60% to 73%) and at one-year follow-up with deep brain stimulation (rate = 73%, 95% CI = 63% to 82%). Conclusions The evidence from RCTs suggests that excitatory M1 stimulation—specifically, anodal M1 tDCS—has a significant short-term effect in reducing pain scale scores in PLP. Various neuromodulation techniques appear to have a significant and positive impact on PLP, but due to the limited amount of data, it is not possible to draw more definite conclusions.