Abstract
BackgroundThe primary motor cortex (M1) is an effective target of non-invasive cortical stimulation (NICS) for pain threshold modulation. It has been suggested that the initial level of cortical excitability of M1 plays a key role in the plastic effects of NICS.ObjectiveHere we investigate whether transcranial direct current stimulation (tDCS) primed 1 Hz repetitive transcranial magnetic stimulation (rTMS) modulates experimental pressure pain thresholds and if this is related to observed alterations in cortical excitability.Method15 healthy, male participants received 10 min 1 mA anodal, cathodal and sham tDCS to the left M1 before 15 min 1 Hz rTMS in separate sessions over a period of 3 weeks. Motor cortical excitability was recorded at baseline, post-tDCS priming and post-rTMS through recording motor evoked potentials (MEPs) from right FDI muscle. Pressure pain thresholds were determined by quantitative sensory testing (QST) through a computerized algometer, on the palmar thenar of the right hand pre- and post-stimulation.ResultsCathodal tDCS-primed 1 Hz-rTMS was found to reverse the expected suppressive effect of 1 Hz rTMS on cortical excitability; leading to an overall increase in activity (p<0.001) with a parallel increase in pressure pain thresholds (p<0.01). In contrast, anodal tDCS-primed 1 Hz-rTMS resulted in a corresponding decrease in cortical excitability (p<0.05), with no significant effect on pressure pain.ConclusionThis study demonstrates that priming the M1 before stimulation of 1 Hz-rTMS modulates experimental pressure pain thresholds in a safe and controlled manner, producing a form of analgesia.
Highlights
Pain perception and modulation have become crucial topics of exploration within the scientific community due to increasing numbers seeking treatment for pain and the current inadequacy of available therapies
Anodal transcranial direct current stimulation (tDCS)-primed 1 Hz-repetitive transcranial magnetic stimulation (rTMS) resulted in a corresponding decrease in cortical excitability (p,0.05), with no significant effect on pressure pain
This study demonstrates that priming the M1 before stimulation of 1 Hz-rTMS modulates experimental pressure pain thresholds in a safe and controlled manner, producing a form of analgesia
Summary
Pain perception and modulation have become crucial topics of exploration within the scientific community due to increasing numbers seeking treatment for pain and the current inadequacy of available therapies. Algometry is used for the assessment of pressure pain thresholds in these patients with chronic musculoskeletal pain. Measurement of these pressure pain thresholds and assessment of the defined 18 tender points forms part of the American College of Rheumatology (ACR) guidelines for the diagnosis of fibromyalgia [2]. Testing pressure pain thresholds at both these tender points and control sites in healthy participants in concert with novel therapies will be important to increase the understanding of alterations in pain processing in these patients. The primary motor cortex (M1) is an effective target of non-invasive cortical stimulation (NICS) for pain threshold modulation. It has been suggested that the initial level of cortical excitability of M1 plays a key role in the plastic effects of NICS
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
