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