University of Groningen A Novel Magnetic Stimulator Increases Experimental Pain Tolerance in Healthy Volunteers Kortekaas,

The ‘complex neural pulse’ (CNP) is a neuromodulation protocol employing weak pulsed electromagnetic fields (PEMF). A pioneering paper reported an analgesic effect in healthy humans after 30 minutes of CNP-stimulation using three nested whole head coils. We aimed to devise and validate a stimulator with a novel design entailing a multitude of small coils at known anatomical positions on a head cap, to improve applicability. The main hypothesis was that CNP delivery with this novel device would also increase heat pain thresholds. Twenty healthy volunteers were enrolled in this double-blind, shamcontrolled, crossover study. Thirty minutes of PEMF (CNP) or sham was applied to the head. After one week the other treatment was given. Before and after each treatment, primary and secondary outcomes were measured. Primary outcome was heat pain threshold (HPT) measured with thermal quantitative sensory testing. Other outcomes were warmth detection threshold, and aspects of cognition, emotion and motor performance. As hypothesized heat pain threshold was significantly increased after the PEMF stimulation. All other outcomes were unaltered by the PEMF but there was a trend level reduction of cognitive performance after PEMF stimulation as measured by the digit-symbol substitution task. Results from this pilot study suggest that our device is able to stimulate the brain and to modulate its function. This is in agreement with previous studies that used similar magnetic field strengths to stimulate the brain. Specifically, pain control may be achieved with PEMF and for this analgesic effect, coil design does not appear to play a dominant role. In addition, the flexible configuration with small coils on a head cap improves clinical applicability. Trial Registration: Dutch Cochrane Centre NTR1093 Citation: Kortekaas R, van Nierop LE, Baas VG, Konopka K-H, Harbers M, et al. (2013) A Novel Magnetic Stimulator Increases Experimental Pain Tolerance in Healthy Volunteers A Double-Blind Sham-Controlled Crossover Study. PLoS ONE 8(4): e61926. doi:10.1371/journal.pone. 0061926 Editor: Sam Eldabe, The James Cook University Hospital, United Kingdom Received September 5, 2012; Accepted March 17, 2013; Published April 1 , 2013 Copyright: 2013 Kortekaas et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Source of funding: University Medical Center Groningen, The Netherlands. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Co-authors André Aleman and Natasha Maurits are PLOS ONE Editorial Board members. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: r.kortekaas@umcg.nl ¤ Current address: Institute for Risk Assessment Science, University of Utrecht, Utrecht, The Netherlands . These authors contributed equally to this work.