Effect of dry-electrode-based transcranial direct current stimulation on chronic low back pain and low back muscle activities: A double-blind sham-controlled study

Article type: Research Article

Authors: Jiang, Naifu^{a; b; c} | Wei, Jinsong^d | Li, Guangsheng^{c; d} | Wei, Bo^d | Zhu, Frank F.^c | Hu, Yong^{c; *}

Affiliations: [a] CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China | [b] The Shenzhen Engineering Laboratory of Neural Rehabilitation Technology, Shenzhen, China | [c] Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong | [d] Department of Orthopaedics, Spinal Division, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China

Correspondence: [*] Corresponding author: Dr. Yong Hu, Department of Orthopaedics and Traumatology, The University of Hong Kong, 12 Sandy Bay Road, Pokfulam, Hong Kong. Tel.: +(852) 29740359; Fax: +(852) 29740335; E-mail: yhud@hku.hk.

Abstract: Background:Dry-electrode-based transcranial direct current stimulation is a new type of non-invasive brain stimulation system which relieves chronic low back pain and improves related muscle movement, in a way that overcomes the drawback of conventional systems. Objective:To investigate the effectiveness of dry-electrode-based transcranial direct current stimulation in relieving chronic low back pain and altering pain-related low back muscles movement, by using pain assessment tool and surface electromyographic topography. Methods:We conducted a prospective, double-blind, randomized, sham-controlled study. 60 patients with non-specific chronic low back pain were randomly and evenly allocated into tDCS and sham groups. Each group accepted a single 20-minute stimulation at 2 mA on the primary motor cortex. Numeric rating scale for pain intensity assessment and root-mean-square difference parameter from surface electromyographic topography were measured before and after stimulation. The current direction in brain using finite element method was simulated to verify the current distribution under dry stimulation electrode. Results:After stimulation, the pain intensity in the tDCS group significantly decreased, while it did not show evident change in the sham group. However, change of root-mean-square difference parameters between tDCS and sham groups showed no significant difference. Simulation results based on finite element method showed most of current focused on primary motor cortex while peak value of current density was 0.225 A/m2. Conclusions:Dry-electrode-based transcranial direct current stimulation can lower pain perception in patients with chronic low back pain. The analgesic mechanism can affect the top-down modulation pathway of pain.

Keywords: Pain measurement, finite element analysis, analgesia, electrodes

DOI: 10.3233/RNN-190922

Journal: Restorative Neurology and Neuroscience, vol. 38, no. 1, pp. 41-54, 2020