High frequency electrical stimulation concurrently induces central sensitization and ipsilateral inhibitory pain modulation
Article first published online: 14 AUG 2012
© 2012 European Federation of International Association for the Study of Pain Chapters
European Journal of Pain
Volume 17, Issue 3, pages 357–368, March 2013
How to Cite
Vo, L. and Drummond, P.D. (2013), High frequency electrical stimulation concurrently induces central sensitization and ipsilateral inhibitory pain modulation. European Journal of Pain, 17: 357–368. doi: 10.1002/j.1532-2149.2012.00208.x
This study was supported by the National Health and Medical Research Council of Australia.
Conflicts of interest
The authors have no conflict of interest with the contents of this manuscript.
- Issue published online: 6 FEB 2013
- Article first published online: 14 AUG 2012
- Manuscript Accepted: 17 JUL 2012
- National Health and Medical Research Council of Australia
In healthy humans, analgesia to blunt pressure develops in the ipsilateral forehead during various forms of limb pain. The aim of the current study was to determine whether this analgesic response is induced by ultraviolet B radiation (UVB), which evokes signs of peripheral sensitization, or by high-frequency electrical stimulation (HFS), which triggers signs of central sensitization.
Before and after HFS and UVB conditioning, sensitivity to heat and to blunt and sharp stimuli was assessed at and adjacent to the treated site in the forearm. In addition, sensitivity to blunt pressure was measured bilaterally in the forehead. The effect of ipsilateral versus contralateral temple cooling on electrically evoked pain in the forearm was then examined, to determine whether HFS or UVB conditioning altered inhibitory pain modulation.
UVB conditioning triggered signs of peripheral sensitization, whereas HFS conditioning triggered signs of central sensitization. Importantly, ipsilateral forehead analgesia developed after HFS but not UVB conditioning. In addition, decreases in electrically evoked pain at the HFS-treated site were greater during ipsilateral than contralateral temple cooling, whereas decreases at the UVB-treated site were similar during both procedures.
HFS conditioning induced signs of central sensitization in the forearm and analgesia both in the ipsilateral forehead and the HFS-treated site. This ipsilateral analgesia was not due to peripheral sensitization or other non-specific effects, as it failed to develop after UVB conditioning. Thus, the supra-spinal mechanisms that evoke central sensitization might also trigger a hemilateral inhibitory pain modulation process. This inhibitory process could sharpen the boundaries of central sensitization or limit its spread.