Background & Aims
Repetitive transcranial magnetic stimulation (rTMS) holds promise as a non-invasive pain treatment. Given the link between individual peak alpha frequency (PAF) of resting-state electroencephalographic recordings and pain sensitivity, and the potential for rTMS to modulate PAF, we investigated these relationships through a secondary analysis of established rTMS-induced analgesia in an experimental model of sustained muscle pain.
Methods
In a randomised, single-blind, sham-controlled experiment, 30 healthy adults underwent either active (n=15) or sham (n=15) high-frequency rTMS (20 min) to the left dorsolateral prefrontal cortex for five consecutive days following induction of sustained experimental pain by nerve growth factor (NGF) injected into the right extensor carpi radialis brevis muscle. The pain intensity was assessed daily for 14 days on a numerical rating scale (NRS). PAF of the resting state electroencephalography (5 min) was assessed before and one day after the five rTMS treatment days.
Results
The beneficial effect of this rTMS treatment on NGF pain were previously published (Seminowicz et al., 2018). The pre-registered secondary analysis of effects on PAF revealed no significant changes in PAF following five consecutive days of active (from 9.90±0.39 Hz to 9.95±0.38 Hz) or sham (from 9.86±0.44 Hz to 9.81±0.35 Hz) rTMS, suggesting that the impact of rTMS on NGF-induced pain is independent of PAF modulation. Exploratory analysis indicated an association between the absolute difference of baseline PAF to 10 Hz (i.e. the rTMS frequency) and higher NRS pain ratings at Day 5 in participants receiving active rTMS.
Conclusions
Contrary to predictions, we found that active rTMS did not significantly increase PAF from baseline compared to sham, despite beneficial effects on NGF-induced pain. Therefore, while PAF has previously shown promise in distinguishing high from low pain sensitive individuals, the present results suggest that changes in experimental pain sensitivity do not necessarily correspond with state changes in PAF. However, exploratory findings indicate that individuals with baseline PAF closer to 10 Hz might be more responsive to rTMS and necessitates further exploration of PAF’s role in rTMS-induced pain relief.
References
Seminowicz, D. A., De Martino, E., Schabrun, S. M., & Graven-Nielsen, T. (2018). Left dorsolateral prefrontal cortex repetitive transcranial magnetic stimulation reduces the development of long-term muscle pain. Pain, 159(12), 2486-2492.
Presenting Author
Samantha K. Millard
Poster Authors
Samantha Millard
MSc
Center for Neuroplasticity and Pain
Lead Author
Alan K.I. Chiang
PhD
Neuroscience Research Australia, Sydney, Australia
Lead Author
Nahian Chowdhury
PhD
University of Sydney
Lead Author
Wei-Ju Chang
PhD
Universidy of Newcastle, Callaghan, Australia
Lead Author
Andrew J. Furman
PhD
University of Maryland, Baltimore, USA
Lead Author
Enrico De Martino
Aalborg University
Lead Author
Thomas Graven-Nielsen
Thomas Graven-Nielsen
Lead Author
Siobhan Schabrun
University of Western Ontario
Lead Author
David Seminowicz PhD
University of Western Ontario
Lead Author
Topics
- Pain Imaging