New Developments in Non-invasive Brain Stimulation in Chronic Pain

Purpose of Review: The goal of this review is to present a summary of the recent literature of a non-invasive brain stimulation (NIBS) to alleviate pain in people with chronic pain syndromes. This article reviews the current evidence for the use of transcranial direct current (tDCS) and repetitive transcranial magnetic stimulation (rTMS) to improve outcomes in chronic pain. Finally, we introduce the reader to novel stimulation methods that may improve therapeutic outcomes in chronic pain. Recent Findings: While tDCS is approved for treatment of fibromyalgia in Canada and the European Union, no NIBS method is currently approved for chronic pain in the USA. Increasing sample sizes in randomized clinical trials (RCTs) seems the most efficient way to increase confidence in initial promising results. Trends at funding agencies reveal increased interest and support for NIBS such as recent Requests for Application from the National Institutes of Health. NIBS in conjunction with cognitive behavioral therapy and physical therapy may enhance outcomes in chronic pain. Novel stimulation methods, such as transcranial ultrasound stimulation, await rigorous study in chronic pain. Summary: Excitatory NIBS targeting motor cortex or left dorsolateral prefrontal cortex has the greatest support for ameliorating pain in chronic pain patients, particularly in Chronic Overlapping Pain Conditions, such as fibromyalgia. Confidence in the efficacy of NIBS interventions is most negatively affected by RCTs with small sample sizes. Increased attention from funding agencies to the promise of NIBS and to the problem of small sample sizes in applied neuroscience is anticipated to improve confidence in these relatively side-effect-free interventions.