Evaluation of a home-based transcranial direct current stimulation (tDCS) treatment device for chronic pain: Study protocol for a randomised controlled trial

Abstract

Background: Stimulation of the primary motor cortex (M1) has been shown to reduce the pain of neuropathy in multiple studies. There are several methods of stimulation both invasive and non-invasive. Recent work by this laboratory has seen that 40% of a sample of chronic neuropathic pain patients responded positively to non-invasive repetitive transcranial magnetic stimulation (rTMS) to the motor cortex with a reduction in pain levels by at least 20%. The effect however is short lived and multiple return visits are necessary to maintain this response. Transcranial direct current stimulation (tDCS) offers a more mobile method of motor cortex stimulation and is similarly non-invasive. The protocol described is designed to assess the analgesic effect of a home-based tDCS treatment device on chronic neuropathic pain in both responders and non-responders to previous TMS treatment. Methods/design: This article reports the protocol for a randomised, sham-controlled, double-blinded crossover study in which patients with chronic neuropathic pain (n = 24) will receive anodal, cathodal and sham tDCS over M1. All patients will have previously completed a study of rTMS of the motor cortex and have been designated as responders or non-responders to this modality. Discussion: The result of this trial will assess the efficacy of self-administered tDCS of the motor cortex in the treatment of chronic neuropathic pain and also provide insight into whether a potential differential effect is seen in patients that have previously been shown to be either responsive or non-responsive to rTMS over the same area. Trial registration: ISRCTN56839387 date 27 January 2014. First patient randomised to trial 30 October 2012.