Not an aspirin: No evidence for acute anti-nociception to laser-evoked pain after motor cortex rTMS in healthy humans

Bradley, Claire, Perchet, Caroline, Lelekov-Boissard, Taissia, Magnin, Michel and Garcia-Larrea, Luis (2016) Not an aspirin: No evidence for acute anti-nociception to laser-evoked pain after motor cortex rTMS in healthy humans. Brain Stimulation, 9 1: 48-57. doi:10.1016/j.brs.2015.08.015

Author Bradley, Claire
Perchet, Caroline
Lelekov-Boissard, Taissia
Magnin, Michel
Garcia-Larrea, Luis
Title Not an aspirin: No evidence for acute anti-nociception to laser-evoked pain after motor cortex rTMS in healthy humans
Journal name Brain Stimulation   Check publisher's open access policy
ISSN 1876-4754
Publication date 2016-01-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.brs.2015.08.015
Open Access Status Not yet assessed
Volume 9
Issue 1
Start page 48
End page 57
Total pages 10
Place of publication Philadelphia, United States
Publisher Elsevier
Language eng
Formatted abstract
High-frequency repetitive transcranial magnetic stimulation (HF-rTMS) has shown efficacy in relieving neuropathic pain. Whether its analgesic effect also applies to acute physiological nociception remains unclear due to previous contradictory findings.

To provide an in-depth investigation of the effects of motor cortex HF-rTMS on acute laser-evoked pain and excitability of nociceptive networks in healthy subjects.

Randomized, placebo-controlled, double-blind, cross-over study in 20 healthy participants. Laser heat stimuli at nociceptive threshold were delivered to the right hand, allowing assessment of: (a) subjective pain intensity and unpleasantness; (b) laser-evoked potentials (LEPs, 128 electrodes) and their source model; (c) sympathetic skin responses, and (d) spino-thalamic pathway excitability. Data were collected before and 20 minutes after a session of neuro-navigated 20 Hz rTMS to the contralateral motor cortex.

Subjective pain reports to thermal laser pulses, amplitude of late cortical potentials and sympathetic skin responses were decreased after cortical stimulation, to a similar extent whether it was active or placebo. Early cortical potentials and nociceptive network excitability remained identical before and after rTMS, as did anatomical sources of LEPs.

Our results do not provide evidence for a genuine anti-nociceptive effect of rTMS on acute physiological pain. We suggest that motor cortex rTMS may act upon high-order networks linked to the emotional and cognitive appraisal of chronic pain, and/or modulate pathologically sensitized networks, rather than change the physiological transmission within an intact nervous system. Such dichotomy is reminiscent of that observed with most drugs used for neuropathic pain.
Keyword Excitability
Laser evoked potentials
Motor cortex stimulation
Neuropathic pain
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Queensland Brain Institute Publications
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